1
|
Maltsev DS, Kulikov AN, Kazak AA. Photoreceptor outer segment layer contributes to optical coherence tomography signal attenuation beneath neurosensory detachments. Eye (Lond) 2022; 36:1795-1798. [PMID: 34373608 PMCID: PMC9391425 DOI: 10.1038/s41433-021-01736-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 07/22/2021] [Accepted: 07/29/2021] [Indexed: 11/08/2022] Open
Abstract
PURPOSE To establish the factors responsible for attenuation of the optical coherence tomography (OCT) signal beneath the neurosensory detachment (NSD). METHODS We retrospectively reviewed 33 eyes with acute central serous chorioretinopathy. The thickness of the neurosensory retina, the thickness of the photoreceptor outer segment (PROS) layer, the height of the NSD, and the reflectivity of the underlying retinal pigment epithelium (RPE) were measured at selected points of B-scans exported from 6 × 6 mm OCT angiography protocols. The intensity of the flow signal was measured at the corresponding regions of the choriocapillaris slab. The correlation between the parameters of the NSD and both the reflectivity of underlying RPE and the intensity of the flow signal in the choriocapillaris was calculated. RESULTS Correlation coefficients between RPE reflectivity and neurosensory retinal thickness, PROS layer thickness, and NSD height were -0.32, -0.64, and -0.25, respectively (p < 0.001). Correlation coefficients between the intensity of the flow signal and neurosensory retinal thickness, PROS layer thickness, and NSD height were -0.24 (p = 0.004), -0.52 (p < 0.001), and 0.13 (p = 0.13), respectively. CONCLUSION The thickness of the PROS layer is the most significant factor affecting OCT signal at the level of RPE and OCT angiography flow signal in the choriocapillaris beneath the NSD.
Collapse
Affiliation(s)
- Dmitrii S Maltsev
- Department of Ophthalmology, Military Medical Academy, St. Petersburg, Russian Federation.
| | - Alexei N Kulikov
- Department of Ophthalmology, Military Medical Academy, St. Petersburg, Russian Federation
| | - Alina A Kazak
- Department of Ophthalmology, Military Medical Academy, St. Petersburg, Russian Federation
| |
Collapse
|
2
|
High speed, long range, deep penetration swept source OCT for structural and angiographic imaging of the anterior eye. Sci Rep 2022; 12:992. [PMID: 35046423 PMCID: PMC8770693 DOI: 10.1038/s41598-022-04784-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 12/13/2021] [Indexed: 11/24/2022] Open
Abstract
This study reports the development of prototype swept-source optical coherence tomography (SS-OCT) technology for imaging the anterior eye. Advances in vertical-cavity surface-emitting laser (VCSEL) light sources, signal processing, optics and mechanical designs, enable a unique combination of high speed, long range, and deep penetration that addresses the challenges of anterior eye imaging. We demonstrate SS-OCT with a 325 kHz A-scan rate, 12.2 µm axial resolution (in air), and 15.5 mm depth range (in air) at 1310 nm wavelength. The ultrahigh 325 kHz A-scan rate not only facilitates biometry measurements by minimizing acquisition time and thus reducing motion, but also enables volumetric OCT for comprehensive structural analysis and OCT angiography (OCTA) for visualizing vasculature. The 15.5 mm (~ 11.6 mm in tissue) depth range spans all optical surfaces from the anterior cornea to the posterior lens capsule. The 1310 nm wavelength range enables structural OCT and OCTA deep in the sclera and through the iris. Achieving high speed and long range requires linearizing the VCSEL wavenumber sweep to efficiently utilize analog-to-digital conversion bandwidth. Dual channel recording of the OCT and calibration interferometer fringe signals, as well as sweep to sweep wavenumber compensation, is used to achieve invariant 12.2 µm (~ 9.1 µm in tissue) axial resolution and optimum point spread function throughout the depth range. Dynamic focusing using a tunable liquid lens extends the effective depth of field while preserving the lateral resolution. Improved optical and mechanical design, including parallax “split view” iris cameras and stable, ergonomic patient interface, facilitates accurate instrument positioning, reduces patient motion, and leads to improved imaging data yield and measurement accuracy. We present structural and angiographic OCT images of the anterior eye, demonstrating the unique imaging capabilities using representative scanning protocols which may be relevant to future research and clinical applications.
Collapse
|
3
|
Tan J, Foster LJR, Lovicu FJ, Watson SL. Laser-Activated Corneal Adhesive: Retinal Safety in Rabbit Model. Transl Vis Sci Technol 2021; 10:27. [PMID: 34319386 PMCID: PMC8322714 DOI: 10.1167/tvst.10.8.27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 06/28/2021] [Indexed: 11/29/2022] Open
Abstract
Purpose The purpose of this study was to investigate whether laser irradiation, used to activate an adhesive for sealing penetrating corneal incisions, causes any ophthalmoscopically or histologically visible retinal changes. Methods Baseline fundus assessment was conducted prior to laser irradiation of eyes of pigmented Dutch Belted rabbits. Treatment group was 18 eyes with the corneal adhesive activated in situ by a near infrared laser (125 mW for 45 seconds). The positive control group was 18 eyes, each irradiated for 60 seconds at 375, 500, 625, and 750 mW at different retinal locations. Unexposed regions of the retina were used as negative internal control. Ophthalmoscopic assessment was conducted immediately after laser exposure and prior to euthanasia. Retinas were histologically assessed at 0, 3, 72, and 168 hours after treatment. Results No ophthalmoscopically or histologically visible retinal changes were observed in the treatment group immediately, nor up to 168 hours after laser irradiation. In the positive control group, the incidences of ophthalmoscopically visible retinal lesions increased with irradiation power: 5.6% at 375 mW, 16.7% at 500 mW, 44.4% at 625 mW, and 50% at 750 mW. Histologically, retinal damage was observed as coagulative necrosis to all layers of the neural retina, including the retinal pigment epithelium. Conclusions The laser irradiation process used in the corneal adhesive technology did not cause any ophthalmoscopically or histologically visible retinal changes in the in vivo pigmented rabbit model. Prolonged exposure with this laser and at higher power can cause coagulative necrosis to the retina. Translational Relevance The corneal adhesive can be applied in humans without causing laser retinal damage.
Collapse
Affiliation(s)
- Jackie Tan
- The University of Sydney, Save Sight Institute, Discipline of Ophthalmology, Sydney Medical School, Sydney, New South Wales, Australia
| | - Leslie John Ray Foster
- The University of Sydney, Save Sight Institute, Discipline of Ophthalmology, Sydney Medical School, Sydney, New South Wales, Australia
- Bio/polymers Research Group, Department of Chemistry, The University of Alabama in Huntsville, Huntsville, AL, USA
| | - Frank James Lovicu
- The University of Sydney, Save Sight Institute, Discipline of Ophthalmology, Sydney Medical School, Sydney, New South Wales, Australia
| | - Stephanie Louise Watson
- The University of Sydney, Save Sight Institute, Discipline of Ophthalmology, Sydney Medical School, Sydney, New South Wales, Australia
| |
Collapse
|
4
|
Lee S, Khun D, Kumarasinghe GL, De zoysa GH, Sarojini V, Vellara HR, Rupenthal ID, Thakur SS. Ex vivo evaluation of the stability, safety and antibacterial efficacy of an extemporaneous povidone‐iodine preparation for ophthalmic applications. Clin Exp Optom 2021; 102:583-589. [DOI: 10.1111/cxo.12899] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/17/2019] [Accepted: 03/01/2019] [Indexed: 01/29/2023] Open
Affiliation(s)
- Stephen Lee
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand,
| | - Darina Khun
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand,
| | - Gamith L Kumarasinghe
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand,
| | - Gayan H De zoysa
- School of Chemical Sciences, The University of Auckland, Auckland, New Zealand,
| | | | - Hans R Vellara
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand,
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand,
| | - Sachin S Thakur
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, New Zealand,
| |
Collapse
|
5
|
Vos JJ, van Norren D. Thermal cataract, from furnaces to lasers. Clin Exp Optom 2021; 87:372-6. [PMID: 15575810 DOI: 10.1111/j.1444-0938.2004.tb03097.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2003] [Revised: 02/19/2004] [Accepted: 03/01/2004] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Thermal cataract has long been known as an occupational disease in furnace workers. This affliction has virtually disappeared in western countries due to improved working conditions. However, new light sources have appeared on the scene, in particular lasers, which might also be capable of producing thermal cataract. The aim of this survey is to review the history and describe the present state of knowledge. METHODS Experimental work, mainly on rabbits, was reviewed and complemented with the results of calculations on the thermal changes in the ocular media. RESULTS Safe exposure limits were derived over the optical spectrum from the near ultraviolet to the far infrared. CONCLUSIONS Lasers may be a cause of thermal cataract only in the near ultraviolet. Moreover, in this field of research too, it is concluded that science may be regarded as the present state of misunderstanding.
Collapse
|
6
|
Marzejon MJ, Kornaszewski Ł, Bogusławski J, Ciąćka P, Martynow M, Palczewska G, Maćkowski S, Palczewski K, Wojtkowski M, Komar K. Two-photon microperimetry with picosecond pulses. BIOMEDICAL OPTICS EXPRESS 2021; 12:462-479. [PMID: 33659083 PMCID: PMC7899501 DOI: 10.1364/boe.411168] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 06/12/2023]
Abstract
Two-photon vision is a phenomenon associated with the perception of short pulses of near-infrared radiation (900-1200 nm) as a visible light. It is caused by the nonlinear process of two-photon absorption by visual pigments. Here we present results showing the influence of pulse duration and repetition rate of short pulsed lasers on the visual threshold. We compared two-photon sensitivity maps of the retina obtained for subjects with normal vision using a cost-effective fiber laser (λc = 1028.4 nm, τp = 12.2 ps, Frep = 19.17 MHz) and a solid-state laser (λc = 1043.3 nm, τp = 0.253 ps, Frep = 62.65 MHz). We have shown that in accordance with the description of two-photon absorption, the average optical power required for two-photon vision for a fiber laser is 4 times greater than that for a solid-state laser. Mean sensitivity measured for the first one is 5.9 ± 2.8 dB lower than for the second but still 17 dB away from the safety limit, confirming that picosecond light sources can be successfully applied in microperimetry. This development would dramatically reduce the cost and complexity of future clinical devices.
Collapse
Affiliation(s)
- Marcin J. Marzejon
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdańsk University of Technology, G. Narutowicza 11/12, 80-223 Gdańsk, Poland
- International Centre for Translational Eye Research, Institute of Physical Chemistry, PAS, Skierniewicka 10a, 01-230 Warszawa, Poland
| | - Łukasz Kornaszewski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- International Centre for Translational Eye Research, Institute of Physical Chemistry, PAS, Skierniewicka 10a, 01-230 Warszawa, Poland
| | - Jakub Bogusławski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- International Centre for Translational Eye Research, Institute of Physical Chemistry, PAS, Skierniewicka 10a, 01-230 Warszawa, Poland
| | - Piotr Ciąćka
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- International Centre for Translational Eye Research, Institute of Physical Chemistry, PAS, Skierniewicka 10a, 01-230 Warszawa, Poland
| | - Miłosz Martynow
- Baltic Institute of Technology, Al. Zwycięstwa 96/98, 81-451 Gdynia, Poland
- Department of Theoretical Physics and Quantum Information, Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, G. Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Grażyna Palczewska
- International Centre for Translational Eye Research, Institute of Physical Chemistry, PAS, Skierniewicka 10a, 01-230 Warszawa, Poland
- Polgenix, Inc., Department of Medical Devices, Cleveland OH 44106, USA
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA 92697, USA
| | - Sebastian Maćkowski
- Baltic Institute of Technology, Al. Zwycięstwa 96/98, 81-451 Gdynia, Poland
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Toruń, Poland
| | - Krzysztof Palczewski
- International Centre for Translational Eye Research, Institute of Physical Chemistry, PAS, Skierniewicka 10a, 01-230 Warszawa, Poland
- Gavin Herbert Eye Institute, Department of Ophthalmology, University of California, Irvine, CA 92697, USA
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, CA 926978, USA
- Department of Chemistry, University of California, Irvine, CA 926978, USA
| | - Maciej Wojtkowski
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warszawa, Poland
- International Centre for Translational Eye Research, Institute of Physical Chemistry, PAS, Skierniewicka 10a, 01-230 Warszawa, Poland
- Baltic Institute of Technology, Al. Zwycięstwa 96/98, 81-451 Gdynia, Poland
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Toruń, Poland
| | - Katarzyna Komar
- International Centre for Translational Eye Research, Institute of Physical Chemistry, PAS, Skierniewicka 10a, 01-230 Warszawa, Poland
- Baltic Institute of Technology, Al. Zwycięstwa 96/98, 81-451 Gdynia, Poland
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziądzka 5, 87-100 Toruń, Poland
| |
Collapse
|
7
|
Light-induced release of the cardioprotective peptide angiotensin-(1–9) from thermosensitive liposomes with gold nanoclusters. J Control Release 2020; 328:859-872. [DOI: 10.1016/j.jconrel.2020.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 10/11/2020] [Accepted: 11/01/2020] [Indexed: 11/24/2022]
|
8
|
Łabuz G, Rayamajhi A, Usinger J, Komar K, Merz P, Khoramnia R, Palczewska G, Palczewski K, Auffarth GU. Clinical Application of Infrared-Light Microperimetry in the Assessment of Scotopic-Eye Sensitivity. Transl Vis Sci Technol 2020; 9:7. [PMID: 32855854 PMCID: PMC7422764 DOI: 10.1167/tvst.9.8.7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/18/2020] [Indexed: 11/24/2022] Open
Abstract
Purpose The eye can see pulsed near-infrared (IR) radiation with the color corresponding to half of the wavelength used. Until recently, the technology required for measuring IR vision was confined to optical laboratories and was not studied clinically. The current investigation sought to determine the values for IR thresholds in a healthy population. Methods IR-light threshold was measured in 45 healthy participants, aged from 21 to 70 years. Ten patients with retinal pathology were included for comparison. Ocular media clarity was assessed with a straylight parameter. The sensitivity of dark-adapted eyes (expressed on a 0-26 dB scale) were tested using an IR microperimeter. The device consists of a femtosecond laser that emits 1045 nm light to project a stimulus at the retina. Results All participants were able to see the IR stimulus, which they perceived as green, and all performed the test. Measurements at seven locations revealed lower sensitivity at the fovea (15.5 dB) than in paracentral regions (18.2 dB). We noted a significant straylight increase with age. Although, in our study population, it was only a slight, -0.18 dB decline per decade of the average IR-sensitivity. The retinal-pathology group demonstrated impaired sensitivity to IR light. Conclusions We showed that IR-light sensitivity does not significantly decrease with age despite a straylight increase. A reference level for the IR threshold was proposed. The application of IR-light microperimetry can be extended to the assessment of retinal pathology. Translational Relevance IR-light microperimetry could be applied clinically to measure visual function.
Collapse
Affiliation(s)
- Grzegorz Łabuz
- The David J. Apple Center for Vision Research, Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Asu Rayamajhi
- The David J. Apple Center for Vision Research, Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Julia Usinger
- The David J. Apple Center for Vision Research, Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Katarzyna Komar
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, Poland
- Baltic Institute of Technology, Gdynia, Poland
| | - Patrick Merz
- The David J. Apple Center for Vision Research, Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Ramin Khoramnia
- The David J. Apple Center for Vision Research, Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| | - Grazyna Palczewska
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA, USA
- Polgenix, Inc., Department of Medical Devices, Irvine, CA, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, CA, USA
- Departments of Physiology & Biophysics, School of Medicine, and Chemistry, University of California, Irvine, CA, USA
| | - Gerd U. Auffarth
- The David J. Apple Center for Vision Research, Department of Ophthalmology, University Hospital Heidelberg, Heidelberg, Germany
| |
Collapse
|
9
|
Hong XJJ, Suchand Sandeep CS, Shinoj VK, Aung T, Barathi VA, Baskaran M, Murukeshan VM. Noninvasive and Noncontact Sequential Imaging of the Iridocorneal Angle and the Cornea of the Eye. Transl Vis Sci Technol 2020; 9:1. [PMID: 32821473 PMCID: PMC7401920 DOI: 10.1167/tvst.9.5.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 12/22/2019] [Indexed: 12/26/2022] Open
Abstract
Purpose High-resolution imaging of the critical anatomic structures of the eye, especially of the anterior chamber, in vivo, remains a challenge, even with currently available state-of-the-art medical imaging techniques. This study aims for the noninvasive and noncontact sequential imaging of the iridocorneal angle, especially the trabecular meshwork (TM) and the cornea of the eye in high-resolution using a newly developed imaging platform. Methods Bessel beam scanned light sheet fluorescence microscopy is used to attain high-resolution images of the TM. The ability of the Bessel beam to self-reconstruct around obstacles increases the image contrast at the TM region inside eye by reducing scattering and shadow artifacts. With minimal modifications, the excitation arm of the developed imaging system is adapted for noncontact, high-resolution corneal imaging. Results High-resolution images of the TM structures and cellular-level corneal structures are obtained in ex vivo porcine eyes, and subsequently in New Zealand white rabbit, in vivo. The spatial resolution of the developed system is 2.19 µm and has a noncontact working distance of 20 mm. Conclusions A high-resolution imaging platform for noncontact sequential imaging of the TM and the cornea of the eye is developed. This imaging system is expected to be of potential interest in the evaluation and diagnosis of glaucoma and corneal diseases. Translational Relevance The developed prototype offers the plausibility of in vivo, noncontact, and high-resolution imaging of the iridocorneal angle and cornea of the eye that will aid clinicians in diagnosing open-angle glaucoma and corneal diseases better.
Collapse
Affiliation(s)
- Xun Jie Jeesmond Hong
- Centre for Optical and Laser Engineering, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore
| | - C S Suchand Sandeep
- Centre for Optical and Laser Engineering, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.,Singapore Centre for 3D Printing, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore
| | - V K Shinoj
- Centre for Optical and Laser Engineering, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.,Currently with Union Christian College, Department of Physics, Kerala, India
| | - Tin Aung
- Singapore Eye Research Institute (SERI) & Singapore National Eye Center (SNEC), Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Veluchamy Amutha Barathi
- Singapore Eye Research Institute (SERI) & Singapore National Eye Center (SNEC), Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.,The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore
| | - Mani Baskaran
- Singapore Eye Research Institute (SERI) & Singapore National Eye Center (SNEC), Singapore.,The Ophthalmology & Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore
| | - Vadakke Matham Murukeshan
- Centre for Optical and Laser Engineering, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore
| |
Collapse
|
10
|
Jiao L, Fan Y, Wang J, Yang Z. Corneal Damage Effects Induced by a 770-2,500 nm Supercontinuum Light Source. Lasers Surg Med 2019; 52:560-568. [PMID: 31713256 DOI: 10.1002/lsm.23182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/28/2019] [Indexed: 11/12/2022]
Abstract
BACKGROUND AND OBJECTIVES Widespread applications of supercontinuum (SC) source lead to the possibility of ocular damages. However, the corneal damage effects induced by SC have not been explored before. The objectives of this study are to determine the rabbit corneal injury threshold for SC radiation and to examine whether the existing safety guidelines and standards are suitable for the hazard evaluation of this new kind of light source. STUDY DESIGN/MATERIALS AND METHODS A series of experiments was conducted in the New Zealand white rabbit model to determine the corneal damage thresholds induced by a 770-2,500 nm SC source, with a corneal 1/e beam diameter of 0.37 mm. Through slit-lamp biomicroscope, optical coherence tomography (OCT), and histopathology the corneal damage characteristics at the threshold level were revealed. By employing the action spectra determined through the analysis of safety guidelines and standards, the damage thresholds for SC source could be compared with the corresponding exposure limits. RESULTS The determined damage thresholds given in terms of the peak radiant exposure for exposure durations of 2.0 and 10.0 seconds were 2.1 × 103 and 7.4 × 103 J/cm2 , respectively. At threshold level, corneal damages involved the epithelium and the shallower stroma, and no obvious changes could be found in the deep stroma, Descemet's membrane, and endothelium. CONCLUSIONS The exposure limits for the anterior parts of the eye in the wavelength range of 700-1,200 nm are overly conservative. The obtained results contribute to the knowledge base for the hazard evaluation of SC source. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Luguang Jiao
- Beijing Institute of Radiation Medicine, Beijing, People's Republic of China
| | - Yan Fan
- Beijing Institute of Radiation Medicine, Beijing, People's Republic of China
| | - Jiarui Wang
- Beijing Institute of Radiation Medicine, Beijing, People's Republic of China
| | - Zaifu Yang
- Beijing Institute of Radiation Medicine, Beijing, People's Republic of China
| |
Collapse
|
11
|
Qi P, Sun L, Ma J, Yao J, Lin L, Zhang L, Wang Y, Liu W. Ex vivo quantitative analysis of human corneal stroma dehydration by near-infrared absorption spectroscopy. JOURNAL OF BIOPHOTONICS 2019; 12:e201800472. [PMID: 31050858 DOI: 10.1002/jbio.201800472] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 04/25/2019] [Accepted: 05/02/2019] [Indexed: 06/09/2023]
Abstract
Corneal water content and hydrodynamics are critical indicators of eye health. In this work, a convenient method based on near-infrared absorption spectroscopy (NIRA) was presented to measure the relative water content of the corneal stroma ex vivo, which paves the way to measure corneal water content in vivo. The relative water content of fresh corneal stroma during dehydration under natural conditions (temperature, 25.8 ± 0.3°C; humidity, 7.2% ± 0.9%) was monitored in real time, and the characteristic time τ when the relative water content dropped to 90% of the fresh corneal stroma was 140.1 ± 30.6 s. Furthermore, the change in the relative water content over time was found to be linear with a dehydration rate of 0.071% per second, consistent with indirect optical coherence pachymetry but with superior reproducibility and precision. Provided that the NIRA spectrometer is changed to a reflection structure from the current transmission configuration, the NIRA method proposed in this work has great potential for in vivo measurement with the advantages of non-contact, high precision and low cost.
Collapse
Affiliation(s)
- Pengfei Qi
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin, China
| | - Lu Sun
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin, China
- Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guangxi, China
| | - Jiaonan Ma
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin, China
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Jiali Yao
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin, China
| | - Lie Lin
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin, China
| | - Lin Zhang
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin, China
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Yan Wang
- Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin, China
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Weiwei Liu
- Institute of Modern Optics, Nankai University, Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin, China
| |
Collapse
|
12
|
Nussbaumer‐Streit B, Forneris CA, Morgan LC, Van Noord MG, Gaynes BN, Greenblatt A, Wipplinger J, Lux LJ, Winkler D, Gartlehner G. Light therapy for preventing seasonal affective disorder. Cochrane Database Syst Rev 2019; 3:CD011269. [PMID: 30883670 PMCID: PMC6422319 DOI: 10.1002/14651858.cd011269.pub3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Seasonal affective disorder (SAD) is a seasonal pattern of recurrent major depressive episodes that most commonly occurs during autumn or winter and remits in spring. The prevalence of SAD ranges from 1.5% to 9%, depending on latitude. The predictable seasonal aspect of SAD provides a promising opportunity for prevention. This review - one of four reviews on efficacy and safety of interventions to prevent SAD - focuses on light therapy as a preventive intervention. Light therapy is a non-pharmacological treatment that exposes people to artificial light. Mode of delivery and form of light vary. OBJECTIVES To assess the efficacy and safety of light therapy (in comparison with no treatment, other types of light therapy, second-generation antidepressants, melatonin, agomelatine, psychological therapies, lifestyle interventions and negative ion generators) in preventing SAD and improving patient-centred outcomes among adults with a history of SAD. SEARCH METHODS We searched Ovid MEDLINE (1950- ), Embase (1974- ), PsycINFO (1967- ) and the Cochrane Central Register of Controlled Trials (CENTRAL) to 19 June 2018. An earlier search of these databases was conducted via the Cochrane Common Mental Disorders Controlled Trial Register (CCMD-CTR) (all years to 11 August 2015). Furthermore, we searched the Cumulative Index to Nursing and Allied Health Literature, Web of Science, the Cochrane Library, the Allied and Complementary Medicine Database and international trial registers (to 19 June 2018). We also conducted a grey literature search and handsearched the reference lists of included studies and pertinent review articles. SELECTION CRITERIA For efficacy, we included randomised controlled trials (RCTs) on adults with a history of winter-type SAD who were free of symptoms at the beginning of the study. For adverse events, we also intended to include non-randomised studies. We intended to include studies that compared any type of light therapy (e.g. bright white light, administered by visors or light boxes, infrared light, dawn stimulation) versus no treatment/placebo, second-generation antidepressants, psychological therapies, melatonin, agomelatine, lifestyle changes, negative ion generators or another of the aforementioned light therapies. We also planned to include studies that looked at light therapy in combination with any comparator intervention. DATA COLLECTION AND ANALYSIS Two review authors screened abstracts and full-text publications, independently abstracted data and assessed risk of bias of included studies. MAIN RESULTS We identified 3745 citations after de-duplication of search results. We excluded 3619 records during title and abstract review. We assessed 126 full-text papers for inclusion in the review, but only one study providing data from 46 people met our eligibility criteria. The included RCT had methodological limitations. We rated it as having high risk of performance and detection bias because of lack of blinding, and as having high risk of attrition bias because study authors did not report reasons for dropouts and did not integrate data from dropouts into the analysis.The included RCT compared preventive use of bright white light (2500 lux via visors), infrared light (0.18 lux via visors) and no light treatment. Overall, white light and infrared light therapy reduced the incidence of SAD numerically compared with no light therapy. In all, 43% (6/14) of participants in the bright light group developed SAD, as well as 33% (5/15) in the infrared light group and 67% (6/9) in the non-treatment group. Bright light therapy reduced the risk of SAD incidence by 36%; however, the 95% confidence interval (CI) was very broad and included both possible effect sizes in favour of bright light therapy and those in favour of no light therapy (risk ratio (RR) 0.64, 95% CI 0.30 to 1.38; 23 participants, very low-quality evidence). Infrared light reduced the risk of SAD by 50% compared with no light therapy, but the CI was also too broad to allow precise estimations of effect size (RR 0.50, 95% CI 0.21 to 1.17; 24 participants, very low-quality evidence). Comparison of both forms of preventive light therapy versus each other yielded similar rates of incidence of depressive episodes in both groups (RR 1.29, 95% CI 0.50 to 3.28; 29 participants, very low-quality evidence). Reasons for downgrading evidence quality included high risk of bias of the included study, imprecision and other limitations, such as self-rating of outcomes, lack of checking of compliance throughout the study duration and insufficient reporting of participant characteristics.Investigators provided no information on adverse events. We could find no studies that compared light therapy versus other interventions of interest such as second-generation antidepressants, psychological therapies, melatonin or agomelatine. AUTHORS' CONCLUSIONS Evidence on light therapy as preventive treatment for people with a history of SAD is limited. Methodological limitations and the small sample size of the only available study have precluded review author conclusions on effects of light therapy for SAD. Given that comparative evidence for light therapy versus other preventive options is limited, the decision for or against initiating preventive treatment of SAD and the treatment selected should be strongly based on patient preferences.
Collapse
Affiliation(s)
- Barbara Nussbaumer‐Streit
- Danube University KremsCochrane Austria, Department for Evidence‐based Medicine and Clinical EpidemiologyDr.‐Karl‐Dorrek‐Str. 30KremsAustria3500
| | - Catherine A Forneris
- University of North Carolina at Chapel HillDepartment of Psychiatry101 Manning Dr., CB# 7160Chapel HillNorth CarolinaUSA27599‐7160
| | - Laura C Morgan
- IBM Watson Health15 Dartford CTChapel HillNorth CarolinaUSA27517
| | - Megan G Van Noord
- University of California DavisCarlson Health Sciences LibraryDavisCaliforniaUSA
| | - Bradley N Gaynes
- University of North Carolina at Chapel HillDepartment of Psychiatry101 Manning Dr., CB# 7160Chapel HillNorth CarolinaUSA27599‐7160
| | - Amy Greenblatt
- Emory UniversityNell Hodgson Woodruff School of NursingAtlantaGeorgiaUSA
| | - Jörg Wipplinger
- Danube University KremsDepartment for Evidence‐based Medicine and Clinical EpidemiologyDr.‐Karl‐Dorrek‐Straße 30KremsAustria3500
| | - Linda J Lux
- RTI International3040 Cornwallis RoadResearch Triangle ParkNorth CarolinaUSA27709
| | - Dietmar Winkler
- Medical University of ViennaDepartment of Psychiatry and PsychotherapyWaehringer Guertel 18‐20ViennaAustria1090
| | - Gerald Gartlehner
- Danube University KremsCochrane Austria, Department for Evidence‐based Medicine and Clinical EpidemiologyDr.‐Karl‐Dorrek‐Str. 30KremsAustria3500
- RTI International3040 Cornwallis RoadResearch Triangle ParkNorth CarolinaUSA27709
| | | |
Collapse
|
13
|
|
14
|
Niederer P, Fankhauser F. Theoretical and practical aspects relating to the photothermal therapy of tumors of the retina and choroid: A review. Technol Health Care 2017; 24:607-26. [PMID: 27129030 DOI: 10.3233/thc-161163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Photothermal treatment of tumors of the retina and choroid such as retinoblastomas, malignant melanomas, benign tumors as well as of vascular malformations can be performed by using laser radiation. A number of basic physical laws have to be taken into account in this procedure. Of particular importance thereby are: Arrhenius' law to approximate the kinetics of protein denaturation and photocoagulation, furthermore the electromagnetic radiation field, the distribution of both radiant and thermal energy induced in tumors and vascular structures, the influence of the wavelength and laser pulse duration (exposure time), as well as of the optical properties of the tissue. Strict confinement of the extent of the photothermal damage is critical since such pathological entities are frequently located close to the macula or optic nerve head.The conditions for tumor destruction are best fulfilled when using radiation in the near-infrared range of the electromagnetic spectrum such as that emitted from the diode (810 nm) and the Nd: YAG (1064 nm) laser, because of the good optical penetration properties of these radiations in tissue. Short wavelength sources of radiation, such as the argon ion (488, 514 nm) or the freqeuency-doubled Nd: YAG (532 nm) laser are less well suited for the irradiation of large vascular structures due to their poor penetration depths. However, for vascular formations with a small thickness (1 mm or less), short wavelength sources appear to be the most appropriate choice. Optical coupling of radiant energy to the eye by means of indirect ophthalmoscopic systems or positive contact lenses is furthermore of importance. Strong positive lenses may lead to severe constrictions of the laser beam within the anterior segment, that leads to high irradiance increasing the probability for structures to be damaged; with negative contact lenses, such as the -64 D Goldmann type lens, this danger is largely absent.
Collapse
Affiliation(s)
- P Niederer
- Institute for Biomedical Engineering, University and Swiss Federal Institute of Technology, Zürich, Switzerland
| | | |
Collapse
|
15
|
Deng X, Korogiannaki M, Rastegari B, Zhang J, Chen M, Fu Q, Sheardown H, Filipe CDM, Hoare T. "Click" Chemistry-Tethered Hyaluronic Acid-Based Contact Lens Coatings Improve Lens Wettability and Lower Protein Adsorption. ACS APPLIED MATERIALS & INTERFACES 2016; 8:22064-22073. [PMID: 27509015 DOI: 10.1021/acsami.6b07433] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Improving the wettability of and reducing the protein adsorption to contact lenses may be beneficial for improving wearer comfort. Herein, we describe a simple "click" chemistry approach to surface functionalize poly(2-hydroxyethyl methacrylate) (pHEMA)-based contact lenses with hyaluronic acid (HA), a carbohydrate naturally contributing to the wettability of the native tear film. A two-step preparation technique consisting of laccase/TEMPO-mediated oxidation followed by covalent grafting of hydrazide-functionalized HA via simple immersion resulted in a model lens surface that is significantly more wettable, more water retentive, and less protein binding than unmodified pHEMA while maintaining the favorable transparency, refractive, and mechanical properties of a native lens. The dipping/coating method we developed to covalently tether the HA wetting agent is simple, readily scalable, and a highly efficient route for contact lens modification.
Collapse
Affiliation(s)
- Xudong Deng
- Department of Chemical Engineering, McMaster University , Hamilton, Ontario L8S 4L7, Canada
| | - Myrto Korogiannaki
- Department of Chemical Engineering, McMaster University , Hamilton, Ontario L8S 4L7, Canada
| | - Banafsheh Rastegari
- Department of Chemical Engineering, McMaster University , Hamilton, Ontario L8S 4L7, Canada
- Department of Biology, Faculty of Sciences, Shiraz University , Shiraz, Fars 71946-84636, Iran
| | - Jianfeng Zhang
- Department of Chemical Engineering, McMaster University , Hamilton, Ontario L8S 4L7, Canada
| | - Mengsu Chen
- School of Nursing, McMaster University , Hamilton, Ontario L8S 4L8, Canada
| | - Qiang Fu
- Department of Chemical Engineering, McMaster University , Hamilton, Ontario L8S 4L7, Canada
| | - Heather Sheardown
- Department of Chemical Engineering, McMaster University , Hamilton, Ontario L8S 4L7, Canada
| | - Carlos D M Filipe
- Department of Chemical Engineering, McMaster University , Hamilton, Ontario L8S 4L7, Canada
| | - Todd Hoare
- Department of Chemical Engineering, McMaster University , Hamilton, Ontario L8S 4L7, Canada
| |
Collapse
|
16
|
Wang J, Jiao L, Jing X, Chen H, Hu X, Yang Z. Retinal thermal damage threshold dependence on exposure duration for the transitional near-infrared laser radiation at 1319 nm. BIOMEDICAL OPTICS EXPRESS 2016; 7:2016-21. [PMID: 27231639 PMCID: PMC4871099 DOI: 10.1364/boe.7.002016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 05/15/2023]
Abstract
The retinal damage effects induced by transitional near-infrared (NIR) lasers have been investigated for years. However, the damage threshold dependence on exposure duration has not been revealed. In this paper, the in-vivo retinal damage ED50 thresholds were determined in chinchilla grey rabbits for 1319 nm laser radiation for exposure durations from 0.1 s to 10 s. The incident corneal irradiance diameter was fixed at 5 mm. The ED50 thresholds given in terms of the total intraocular energy (TIE) for exposure durations of 0.1, 1 and 10 s were 1.36, 6.33 and 28.6 J respectively. The ED50 thresholds were correlated by a power law equation, ED50 = 6.31t (0.66) [J] where t is time [s], with correlation coefficient R = 0.9999. There exists a sufficient safety margin (factor of 28~60) between the human ED50 thresholds derived from the rabbit and the maximum permissible exposure (MPE) values in the current laser safety standards.
Collapse
Affiliation(s)
- Jiarui Wang
- Beijing Institute of Radiation Medicine, Beijing 100850, China
- These authors contributed equally to this work
| | - Luguang Jiao
- Beijing Institute of Radiation Medicine, Beijing 100850, China
- These authors contributed equally to this work
| | - Xiaomin Jing
- Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Hongxia Chen
- Department of Dermatology, First Affiliated Hospital of PLA General Hospital, Beijing 10048, China
| | - Xiangjun Hu
- Beijing Institute of Radiation Medicine, Beijing 100850, China
| | - Zaifu Yang
- Beijing Institute of Radiation Medicine, Beijing 100850, China
| |
Collapse
|
17
|
Nussbaumer B, Kaminski-Hartenthaler A, Forneris CA, Morgan LC, Sonis JH, Gaynes BN, Greenblatt A, Wipplinger J, Lux LJ, Winkler D, Van Noord MG, Hofmann J, Gartlehner G. Light therapy for preventing seasonal affective disorder. Cochrane Database Syst Rev 2015:CD011269. [PMID: 26558494 DOI: 10.1002/14651858.cd011269.pub2] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Seasonal affective disorder (SAD) is a seasonal pattern of recurrent major depressive episodes that most commonly occurs during autumn or winter and remits in spring. The prevalence of SAD ranges from 1.5% to 9%, depending on latitude. The predictable seasonal aspect of SAD provides a promising opportunity for prevention. This review - one of four reviews on efficacy and safety of interventions to prevent SAD - focuses on light therapy as a preventive intervention. Light therapy is a non-pharmacological treatment that exposes people to artificial light. Mode of delivery (e.g. visors, light boxes) and form of light (e.g. bright white light) vary. OBJECTIVES To assess the efficacy and safety of light therapy (in comparison with no treatment, other types of light therapy, second-generation antidepressants, melatonin, agomelatine, psychological therapies, lifestyle interventions and negative ion generators) in preventing SAD and improving patient-centred outcomes among adults with a history of SAD. SEARCH METHODS A search of the Specialised Register of the Cochrane Depression, Anxiety and Neuorosis Review Group (CCDANCTR) included all years to 11 August 2015. The CCDANCTR contains reports of relevant randomised controlled trials derived from EMBASE (1974 to date), MEDLINE (1950 to date), PsycINFO (1967 to date) and the Cochrane Central Register of Controlled Trails (CENTRAL). Furthermore, we searched the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Knowledge, The Cochrane Library and the Allied and Complementary Medicine Database (AMED) (to 26 May 2014). We also conducted a grey literature search and handsearched the reference lists of all included studies and pertinent review articles. SELECTION CRITERIA For efficacy, we included randomised controlled trials on adults with a history of winter-type SAD who were free of symptoms at the beginning of the study. For adverse events, we also intended to include non-randomised studies. We intended to include studies that compared any type of light therapy (e.g. bright white light, administered by visors or light boxes, infrared light, dawn stimulation) versus no treatment/placebo, second-generation antidepressants (SGAs), psychological therapies, melatonin, agomelatine, lifestyle changes, negative ion generators or another of the aforementioned light therapies. We also planned to include studies that looked at light therapy in combination with any comparator intervention and compared this with the same comparator intervention as monotherapy. DATA COLLECTION AND ANALYSIS Two review authors screened abstracts and full-text publications against the inclusion criteria. Two review authors independently abstracted data and assessed risk of bias of included studies. MAIN RESULTS We identified 2986 citations after de-duplication of search results. We excluded 2895 records during title and abstract review. We assessed 91 full-text papers for inclusion in the review, but only one study providing data from 46 people met our eligibility criteria. The included randomised controlled trial (RCT) had methodological limitations. We rated it as having high risk of performance and detection bias because of lack of blinding, and as having high risk of attrition bias because study authors did not report reasons for dropouts and did not integrate data from dropouts into the analysis.The included RCT compared preventive use of bright white light (2500 lux via visors), infrared light (0.18 lux via visors) and no light treatment. Overall, both forms of preventive light therapy reduced the incidence of SAD numerically compared with no light therapy. In all, 43% (6/14) of participants in the bright light group developed SAD, as well as 33% (5/15) in the infrared light group and 67% (6/9) in the non-treatment group. Bright light therapy reduced the risk of SAD incidence by 36%; however, the 95% confidence interval (CI) was very broad and included both possible effect sizes in favour of bright light therapy and those in favour of no light therapy (risk ratio (RR) 0.64, 95% CI 0.30 to 1.38). Infrared light reduced the risk of SAD by 50% compared with no light therapy, but in this case also the CI was too broad to allow precise estimations of effect size (RR 0.50, 95% CI 0.21 to 1.17). Comparison of both forms of preventive light therapy versus each other yielded similar rates of incidence of depressive episodes in both groups (RR 1.29, 95% CI 0.50 to 3.28). The quality of evidence for all outcomes was very low. Reasons for downgrading evidence quality included high risk of bias of the included study, imprecision and other limitations, such as self rating of outcomes, lack of checking of compliance throughout the study duration and insufficient reporting of participant characteristics.Investigators provided no information on adverse events. We could find no studies that compared light therapy versus other interventions of interest such as SGA, psychological therapies, melatonin or agomelatine. AUTHORS' CONCLUSIONS Evidence on light therapy as preventive treatment for patients with a history of SAD is limited. Methodological limitations and the small sample size of the only available study have precluded review author conclusions on effects of light therapy for SAD. Given that comparative evidence for light therapy versus other preventive options is limited, the decision for or against initiating preventive treatment of SAD and the treatment selected should be strongly based on patient preferences.
Collapse
Affiliation(s)
- Barbara Nussbaumer
- Department of Evidence-based Medicine and Clinical Epidemiology, Danube University Krems, Krems, Austria
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Lombardo M, Merino D, Loza-Alvarez P, Lombardo G. Translational label-free nonlinear imaging biomarkers to classify the human corneal microstructure. BIOMEDICAL OPTICS EXPRESS 2015; 6:2803-18. [PMID: 26309745 PMCID: PMC4541509 DOI: 10.1364/boe.6.002803] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 06/10/2015] [Accepted: 06/12/2015] [Indexed: 05/18/2023]
Abstract
Diseases that affect the cornea can lead to severe vision loss and have tremendous social impact. These diseases are associated to deviations from normal structural order and orientation of collagen fibril bundles. Unfortunately, resolving non-invasively the corneal collagen structure is not possible to date. In this work, polarization sensitive second harmonic generation (pSHG) microscopy is used to obtain information with molecular specificity on microstructure of human corneas. This information is used to develop a set of label-free imaging biomarkers that were generated by means of a novel methodology based on mathematical tensorial calculus. The method is proven to be highly sensitive and robust. The use of these biomarkers permits accurate characterization of the anisotropic, depth-dependent, structural organization of corneal collagen fibril bundles without any a priori information. The method can be valuable to improve understanding of microstructural pathophysiological changes of the human cornea close to in vivo conditions.
Collapse
Affiliation(s)
| | - David Merino
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Barcelona, Spain
| | - Pablo Loza-Alvarez
- ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Barcelona, Spain
| | - Giuseppe Lombardo
- CNR-IPCF - Consiglio Nazionale delle Ricerche, Istituto per i Processi Chimico-Fisici, 98158 Messina, Italy
- Vision Engineering Italy srl, 00198 Rome, Italy
| |
Collapse
|
19
|
Hofmann L, Palczewski K. Advances in understanding the molecular basis of the first steps in color vision. Prog Retin Eye Res 2015; 49:46-66. [PMID: 26187035 DOI: 10.1016/j.preteyeres.2015.07.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 07/07/2015] [Accepted: 07/09/2015] [Indexed: 01/05/2023]
Abstract
Serving as one of our primary environmental inputs, vision is the most sophisticated sensory system in humans. Here, we present recent findings derived from energetics, genetics and physiology that provide a more advanced understanding of color perception in mammals. Energetics of cis-trans isomerization of 11-cis-retinal accounts for color perception in the narrow region of the electromagnetic spectrum and how human eyes can absorb light in the near infrared (IR) range. Structural homology models of visual pigments reveal complex interactions of the protein moieties with the light sensitive chromophore 11-cis-retinal and that certain color blinding mutations impair secondary structural elements of these G protein-coupled receptors (GPCRs). Finally, we identify unsolved critical aspects of color tuning that require future investigation.
Collapse
Affiliation(s)
- Lukas Hofmann
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
| | - Krzysztof Palczewski
- Department of Pharmacology and Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
| |
Collapse
|
20
|
Light induced cytosolic drug delivery from liposomes with gold nanoparticles. J Control Release 2015; 203:85-98. [PMID: 25701610 DOI: 10.1016/j.jconrel.2015.02.028] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/11/2015] [Accepted: 02/17/2015] [Indexed: 11/23/2022]
Abstract
Externally triggered drug release at defined targets allows site- and time-controlled drug treatment regimens. We have developed liposomal drug carriers with encapsulated gold nanoparticles for triggered drug release. Light energy is converted to heat in the gold nanoparticles and released to the lipid bilayers. Localized temperature increase renders liposomal bilayers to be leaky and triggers drug release. The aim of this study was to develop a drug releasing system capable of releasing its cargo to cell cytosol upon triggering with visible and near infrared light signals. The liposomes were formulated using either heat-sensitive or heat- and pH-sensitive lipid compositions with star or rod shaped gold nanoparticles. Encapsulated fluorescent probe, calcein, was released from the liposomes after exposure to the light. In addition, the pH-sensitive formulations showed a faster drug release in acidic conditions than in neutral conditions. The liposomes were internalized into human retinal pigment epithelial cells (ARPE-19) and human umbilical vein endothelial cells (HUVECs) and did not show any cellular toxicity. The light induced cytosolic delivery of calcein from the gold nanoparticle containing liposomes was shown, whereas no cytosolic release was seen without light induction or without gold nanoparticles in the liposomes. The light activated liposome formulations showed a controlled content release to the cellular cytosol at a specific location and time. Triggering with visual and near infrared light allows good tissue penetration and safety, and the pH-sensitive liposomes may enable selective drug release in the intracellular acidic compartments (endosomes, lysosomes). Thus, light activated liposomes with gold nanoparticles are an attractive option for time- and site-specific drug delivery into the target cells.
Collapse
|
21
|
Ebisawa Y, Fukumoto K. Head-Free, Remote Eye-Gaze Detection System Based on Pupil-Corneal Reflection Method With Easy Calibration Using Two Stereo-Calibrated Video Cameras. IEEE Trans Biomed Eng 2013; 60:2952-60. [DOI: 10.1109/tbme.2013.2266478] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
22
|
Abstract
Anterior segment imaging allows objective assessment of the anterior segment of the eye, particularly the anterior chamber angle. Both qualitative and quantitative analyses are possible and aid in detecting and managing closed-angle and open-angle mechanisms in various forms of glaucoma. This review focuses primarily on anterior segment optical coherence tomography and ultrasound biomicroscopy, with emphasis on principles of technology, commercially available devices, and clinical applications in glaucoma with potential advantages and disadvantages of each technology.
Collapse
Affiliation(s)
- Sarwat Salim
- Glaucoma Service, Hamilton Eye Institute, University of Tennessee Health Science Center, Memphis, TN, USA.
| | | |
Collapse
|
23
|
The role of anterior segment optical coherence tomography in glaucoma. J Ophthalmol 2012; 2012:476801. [PMID: 22900146 PMCID: PMC3415232 DOI: 10.1155/2012/476801] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 06/10/2012] [Indexed: 01/10/2023] Open
Abstract
The anterior segment optical coherence tomography provides an objective method to assess the anterior segment of the eye, including the anatomy of the anterior chamber angle. This technology allows both qualitative and quantitative analyses of the angle and has shown potential in detecting and managing angle-closure glaucoma. In addition, it has a role in identifying pathology in some forms of secondary open-angle glaucoma and postsurgical management of glaucoma. Limitations of this technology include its cost and inability to visualize well structures posterior to the iris, such as the ciliary body. This paper focuses on potential benefits and limitations of anterior segment optical coherence tomography when compared with conventional gonioscopy and ultrasound biomicroscopy. Various clinical entities will be described to discuss its potential role in glaucoma practice.
Collapse
|
24
|
Marschall S, Pedersen C, Andersen PE. Investigation of the impact of water absorption on retinal OCT imaging in the 1060 nm range. BIOMEDICAL OPTICS EXPRESS 2012; 3:1620-31. [PMID: 22808433 PMCID: PMC3395486 DOI: 10.1364/boe.3.001620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 05/31/2012] [Accepted: 06/08/2012] [Indexed: 05/22/2023]
Abstract
Recently, the wavelength range around 1060 nm has become attractive for retinal imaging with optical coherence tomography (OCT), promising deep penetration into the retina and the choroid. The adjacent water absorption bands limit the useful bandwidth of broadband light sources, but until now, the actual limitation has not been quantified in detail. We have numerically investigated the impact of water absorption on the axial resolution and signal amplitude for a wide range of light source bandwidths and center wavelengths. Furthermore, we have calculated the sensitivity penalty for maintaining the optimal resolution by spectral shaping. As our results show, with currently available semiconductor-based light sources with up to 100-120 nm bandwidth centered close to 1060 nm, the resolution degradation caused by the water absorption spectrum is smaller than 10%, and it can be compensated by spectral shaping with negligible sensitivity penalty. With increasing bandwidth, the resolution degradation and signal attenuation become stronger, and the optimal operating point shifts towards shorter wavelengths. These relationships are important to take into account for the development of new broadband light sources for OCT.
Collapse
|
25
|
Heselich A, Frohns F, Frohns A, Naumann SC, Layer PG. Near-infrared exposure changes cellular responses to ionizing radiation. Photochem Photobiol 2011; 88:135-46. [PMID: 22053955 DOI: 10.1111/j.1751-1097.2011.01031.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Near infrared (NIR) and X-rays are radiations from different sides of the wavelength spectrum but both are used during medical treatments, as they have severe impacts on cellular processes, including metabolism, gene expression, proliferation and survival. However, both radiations differ strictly in their consequences for exposed patients: NIR effects are generally supposed to be positive, mostly ascribed to a stimulation of metabolism, whereas X-ray leads to genetic instability, an increase of reactive oxygen species (ROS) and DNA damages and finally to cellular death by apoptosis in tumor cells. Since genomic stability after X-irradiation depends on the mitochondrial metabolism, which is well known to be regulated by NIR, we analyzed the impact of NIR on cellular responses of fibroblasts, retinal progenitor cells and keratinocytes to X-radiation. Our data show that previous exposure to naturally occurring doses of nonthermal NIR combined with clinically relevant X-ray doses leads to (1) increased genomic instability, indicated by elevated ratios of mitotic catastrophes, (2) increased ROS, (3) higher amounts of X-irradiated cells entering S-phase and (4) impaired DNA double-strand break repair. Taken together, our data show tremendous effects of NIR on cellular responses to X-rays, probably affecting the results of radiotherapy after NIR exposure during cancer treatment.
Collapse
Affiliation(s)
- Anja Heselich
- Developmental Biology and Neurogenetics, TU Darmstadt, Darmstadt, Germany.
| | | | | | | | | |
Collapse
|
26
|
Chen H, Yang Z, Wang J, Chen P, Qian H. A comparative study on ocular damage induced by 1319nm laser radiation. Lasers Surg Med 2011; 43:306-12. [PMID: 21500225 DOI: 10.1002/lsm.21052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND AND OBJECTIVES High energy loss of 1,319 nm laser due to pre-retinal water absorption makes the ocular axial length more critical, while the relative low absorbance of melanin makes retinal pigmented epithelium less contributing, to retinal damage threshold. However, both have never been illustrated experimentally. Here we determined and compared the retinal damage thresholds at this wavelength in three species with different axial lengths and retinal pigmentations. The corneal damage threshold was also determined for further comparative analysis. MATERIALS AND METHODS The retinal damage thresholds of albino rat, non-pigmented and pigmented rabbit, and the corneal damage threshold of non-pigmented rabbit were determined for 0.2 and/or 0.4-second exposure durations. The incident beam diameter on cornea was 5 mm for rabbit retinal and 2 mm for rat retinal and rabbit corneal lesion. Minimum visible lesions were examined 1- and 24-hour post-exposure. Probit analysis was used to establish the estimated damage threshold for 50% of exposures (ED(50) ). The direct transmittance of pre-retinal eye media was used for further comparative analysis. RESULTS The retinal ED(50) of albino rat for 0.2 seconds, non-pigmented rabbit for 0.2 seconds, 0.4 seconds, pigmented rabbit for 0.4 seconds was 8.8, 12.1, 22.5, 18.5 J/cm(2) (0.28, 2.4, 4.4, 3.6 J in total intraocular energy (TIE)). The corneal ED(50) was 86.1 J/cm(2) . Under the condition of 5 mm beam diameter and 0.4-second exposure duration, the calculated retinal ED(50) of human was higher, while that of rhesus monkey was lower than the corneal ED(50) . CONCLUSION For 1,319 nm laser radiation, the ocular axial length has great, while the retinal pigmentation has only slight influence on retinal damage threshold. The relative lower direct transmittance of human eye media makes the retina more resistant to laser lesion, which should be considered when deriving human maximum permissible exposure (MPE).
Collapse
Affiliation(s)
- Hongxia Chen
- Department of Laser Medicine, Chinese PLA General Hospital, Beijing 100853, P.R. China
| | | | | | | | | |
Collapse
|
27
|
Liao D, Yu H, Zhang Y, Li B. Photothermal delivery of microscopic objects via convection flows induced by laser beam from fiber tip. APPLIED OPTICS 2011; 50:3711-3716. [PMID: 21743585 DOI: 10.1364/ao.50.003711] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report a photothermal delivery of microscopic objects based on convection flows at the surface of water. The convection flows were induced by photothermal effect through a laser beam of 1.55 μm wavelength from a fiber tip. A 206 μm diameter oil drop was delivered forward and backward by changing the laser beam at a power of 28.5-40 mW. In addition, the delivery has been further demonstrated with a cluster of carbon and red blood cells at the laser powers of 14 and 20 mW, respectively.
Collapse
Affiliation(s)
- Dongwei Liao
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275, China
| | | | | | | |
Collapse
|
28
|
Keane PA, Ruiz-Garcia H, Sadda SR. Clinical Applications of Long-Wavelength (1,000-nm) Optical Coherence Tomography. Ophthalmic Surg Lasers Imaging Retina 2011; 42 Suppl:S67-74. [DOI: 10.3928/15428877-20110627-06] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 04/05/2011] [Indexed: 11/20/2022]
|
29
|
Yust BG, Mimun LC, Sardar DK. Optical absorption and scattering of bovine cornea, lens, and retina in the near-infrared region. Lasers Med Sci 2011; 27:413-22. [PMID: 21556925 DOI: 10.1007/s10103-011-0927-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Accepted: 04/11/2011] [Indexed: 11/30/2022]
Abstract
The optical properties of bovine ocular tissues have been determined at laser wavelengths in the near-infrared (NIR) region. The inverse adding doubling (IAD), Kubelka-Munk (KM), and inverse Monte Carlo (IMC) methods were applied to the measured values of the total diffuse transmission, total diffuse reflection, and collimated transmission to determine the optical absorption and scattering coefficients of the bovine cornea, lens and retina from 750 to 1,000 nm using a CW Ti:sapphire laser. The optical properties obtained from these three methods have been compared and are discussed.
Collapse
Affiliation(s)
- Brian G Yust
- Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249-0697, USA
| | | | | |
Collapse
|
30
|
Abstract
Primary angle closure glaucoma (PACG) is a major form of glaucoma in large populous countries in East and South Asia. The high visual morbidity from PACG is related to the destructive nature of the asymptomatic form of the disease. Early detection of anatomically narrow angles is important and the subsequent prevention of visual loss from PACG depends on an accurate assessment of the anterior chamber angle (ACA). This review paper discusses the advantages and limitations of newer ACA imaging technologies, namely ultrasound biomicroscopy, Scheimpflug photography, anterior segment optical coherence tomography and EyeCam, highlighting the current clinical evidence comparing these devices with each other and with clinical dynamic indentation gonioscopy, the current reference standard.
Collapse
Affiliation(s)
- Desmond T L Quek
- Singapore National Eye Centre, Singapore Eye Research Institute and Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | | | | | | |
Collapse
|
31
|
Doors M, Berendschot TTJM, de Brabander J, Webers CAB, Nuijts RMMA. Value of optical coherence tomography for anterior segment surgery. J Cataract Refract Surg 2010; 36:1213-29. [PMID: 20610103 DOI: 10.1016/j.jcrs.2010.05.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 04/15/2010] [Accepted: 04/18/2010] [Indexed: 11/19/2022]
Abstract
UNLABELLED Anterior segment optical coherence tomography (AS-OCT) is an important new noncontact imaging technology that uses a 1310 nm super luminescent diode. It can be used to assess anterior chamber biometry, corneal thickness, lens thickness, and angle configuration; to visualize pathological processes; to evaluate postsurgical anatomy and posttraumatic eyes; and to image phakic intraocular lenses and intracorneal ring segments. Because it is a noncontact technique, it can also be used intraoperatively, which could be useful during trabeculectomy and after deep anterior lamellar keratoplasty to detect abnormalities in the cornea and interface. A disadvantage of AS-OCT is its inability to penetrate the iris pigment epithelium, which makes it impossible to evaluate the structures behind the iris. The most frequently used devices are time-domain AS-OCT, but new Fourier-domain OCT devices, which have faster image acquisition and higher resolution, are currently under investigation. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned.
Collapse
Affiliation(s)
- Muriël Doors
- Department of Ophthalmology, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | | | | | | |
Collapse
|
32
|
Morarescu D, West-Mays JA, Sheardown HD. Effect of delivery of MMP inhibitors from PDMS as a model IOL material on PCO markers. Biomaterials 2010; 31:2399-407. [PMID: 20022368 PMCID: PMC2972668 DOI: 10.1016/j.biomaterials.2009.11.108] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 11/29/2009] [Indexed: 10/20/2022]
Abstract
Posterior capsule opacification (PCO) or secondary cataract formation, following intraocular lens implantation, is a significant complication affecting an estimated 28% of cataract patients. Matrix metalloproteinases (MMPs) have been demonstrated to play a role in the formation of anterior subcapsular cataracts and it has been shown that the presence of MMP inhibitors (MMPI) decreases subcapsular cataract formation ex vivo. Since the mechanisms responsible for anterior subcapsular cataract formation and posterior capsule opacification are similar, it is reasonable to suggest that MMP inhibitors may also mitigate PCO. One of the most effective ways of delivering the inhibitors may be from the implanted intraocular lens (IOL) material itself. In the current work, delivery of three different MMP inhibitors from silicone rubber as a model IOL material was examined. Loading methods were developed which allowed continuous release of active MMPI for periods of over 5 months in some cases. Reduced migration rates were observed in human lens epithelial cells in vitro, suggesting that an effect on PCO may be possible. While further studies are necessary to tune the systems to achieve the desired rates of release, this work demonstrates that delivery of MMPI from silicone IOL materials has the potential to decrease the incidence of PCO.
Collapse
Affiliation(s)
- Diana Morarescu
- School of Biomedical Engineering, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Judy A. West-Mays
- Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Heather D. Sheardown
- School of Biomedical Engineering, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
- Pathology and Molecular Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada
- Department of Chemical Engineering, McMaster University, Hamilton, ON L8S 4K1, Canada
| |
Collapse
|
33
|
|
34
|
Chen SY, Yu HC, Wang IJ, Sun CK. Infrared-based third and second harmonic generation imaging of cornea. JOURNAL OF BIOMEDICAL OPTICS 2009; 14:044012. [PMID: 19725724 DOI: 10.1117/1.3183805] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The cornea functions as an optical lens and plays an important role in vision. For corneal diagnosis and treatment such as refractive surgery, a microscopic imaging system with a 3-D cellular resolution and retinal safety is strongly desired. Recently, confocal and multiphoton microscopies have been applied to corneal imaging with visible to near-infrared light sources. To increase retinal safety, an infrared light source is be needed. In this work, an infrared-based third and second harmonic generation microscopic study of mouse eyes is reported with approximately 700-mum penetrability and high cellular resolution. This study provides a critical reference for future development of infrared-based corneal imaging.
Collapse
Affiliation(s)
- Szu-Yu Chen
- National Taiwan University, Graduate Institute of Photonics and Optoelectronics, Department of Electrical Engineering, No 1 Roosevelt Road Section 4, Taipei 10617, Taiwan
| | | | | | | |
Collapse
|
35
|
Kernt M, Hirneiss C, Neubauer A, Lackerbauer C, Eibl K, Wolf A, Ulbig MW, Kampik A. Protektive Wirkung Blaulicht absorbierender IOLs auf das menschliche retinale Pigmentepithel. Ophthalmologe 2009; 107:150-7. [DOI: 10.1007/s00347-009-1945-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
36
|
Optical absorption and scattering of bovine cornea, lens and retina in the visible region. Lasers Med Sci 2009; 24:839-47. [PMID: 19495828 DOI: 10.1007/s10103-009-0677-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 04/21/2009] [Indexed: 10/20/2022]
Abstract
Optical properties of bovine ocular tissues were determined at laser wavelengths in the visible region. The inverse adding doubling (IAD), Kubelka-Munk (KM), and inverse Monte Carlo (IMC) methods were applied to the measured values of the total diffuse transmission, total diffuse reflection, and collimated transmission to determine the optical absorption and scattering coefficients of the bovine cornea, lens and retina at 457.9 nm, 488 nm, and 514.5 nm laser lines from an argon ion laser. The optical properties obtained from these three methods were compared, and their validity is discussed.
Collapse
|
37
|
Kernt M, Neubauer AS, Liegl R, Eibl KH, Alge CS, Lackerbauer CA, Ulbig MW, Kampik A. Cytoprotective effects of a blue light-filtering intraocular lens on human retinal pigment epithelium by reducing phototoxic effects on vascular endothelial growth factor-alpha, Bax, and Bcl-2 expression. J Cataract Refract Surg 2009; 35:354-62. [PMID: 19185255 DOI: 10.1016/j.jcrs.2008.10.052] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2008] [Revised: 10/17/2008] [Accepted: 10/21/2008] [Indexed: 10/21/2022]
Abstract
PURPOSE To compare the possible protective effects of the ultraviolet (UV)-filtering and blue light-filtering SN60AT intraocular lens (IOL) and the untinted UV-filtering SA60AT IOL with regard to light-induced stress on human retinal pigment epithelium (RPE). SETTING Department of Ophthalmology, Ludwig-Maximilians-University, Munich, Germany. METHODS Primary human RPE cells were exposed to white light, and a tinted or untinted IOL was placed in the light beam. After 15 to 60 minutes of irradiation, cell viability was determined by a colorimetric test (tetrazolium dye-reduction assay) and a microscopic live/dead assay. The expression of vascular endothelial growth factor-alpha (VEGF-alpha), Bax, and Bcl-2 and their mRNA was determined by reverse-transcription polymerase chain reaction (RT-PCR) and Western blotting. RESULTS Without an IOL, white-light exposure decreased cell viability compared with the decrease with the nonirradiated control in a time-dependent manner. Light-induced cell death was significantly reduced by both the tinted IOL and untinted IOL. The combined UV and blue-light filtering attenuated light-induced cell damage significantly more than UV filtering alone. Results of RT-PCR and Western blotting showed a significant time-dependent decrease in Bcl-2 and increase in Bax and VEGF-alpha that were significantly less with the tinted IOL than with the untinted IOL. CONCLUSIONS Both IOLs reduced light-induced RPE damage. The UV- and blue light-filtering IOL reduced damage more than the conventional IOL. This supports the hypothesis that blue light-filtering IOLs may prevent retinal damage in clinical use.
Collapse
Affiliation(s)
- Marcus Kernt
- Department of Ophthalmology, Ludwig Maximilian University, Munich, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Fukuda S, Kawana K, Yasuno Y, Oshika T. Anterior ocular biometry using 3-dimensional optical coherence tomography. Ophthalmology 2009; 116:882-9. [PMID: 19410946 DOI: 10.1016/j.ophtha.2008.12.022] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Revised: 11/04/2008] [Accepted: 12/05/2008] [Indexed: 10/20/2022] Open
Abstract
PURPOSE To evaluate anterior ocular biometry by comparing the measurements of central corneal thickness (CCT) and anterior chamber depth (ACD) with 3-dimensional corneal and anterior segment optical coherence tomography (CAS-OCT) and other methods. DESIGN Cross-sectional study. PARTICIPANTS Forty eyes of 40 normal subjects. METHODS The CCT was measured by 4 methods (CAS-OCT, Scheimpflug camera, scanning-slit topography, and ultrasonic pachymetry), and the ACD was measured by 3 methods (CAS-OCT, Scheimpflug camera, and scanning-slit topography). The anterior chamber volume (ACV) was calculated with CAS-OCT. Repeatability and reproducibility of CAS-OCT measurements were evaluated. MAIN OUTCOME MEASUREMENTS The CCT and ACD were measured and compared between devices. The ACV was calculated with CAS-OCT. Coefficient of variation and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability and reproducibility of CAS-OCT measurements. RESULTS The mean CCT was 547.0+/-39.0, 590.0+/-39.8, 525.0+/-45.0, and 545.0+/-40.3 microm with CAS-OCT, Scheimpflug camera, scanning-slit topography, and ultrasonic pachymetry, respectively. Significant differences were observed among the 4 methods (P<0.0001; 1-way analysis of variance [ANOVA]). The CCT measured with Scheimpflug camera was significantly larger than those measured with the other methods (P<0.0001; Bonferroni multiple comparison), but there was no significant difference among the other 3 methods. The mean ACD was 3.01+/-0.47, 3.04+/-0.52, and 2.88+/-0.50 mm with CAS-OCT, Scheimpflug camera, and scanning-slit topography, respectively. There was no significant difference among the 3 methods (P = 0.678; 1-way ANOVA). A significant linear correlation in CCT and ACD were observed between CAS-OCT and other methods (all P<0.0001). The mean ACV calculated with CAS-OCT was 169.7+/-23.1 mm(3). The coefficient of repeatability and reproducibility of CCT and ACD measurements were <5% and ICCs were >0.98. CONCLUSIONS The CCT measurements were comparable among CAS-OCT, ultrasonic pachymetry, and scanning-slit topography, but Scheimpflug camera yielded a significantly higher CCT value. There was no significant difference in ACD measurements among CAS-OCT, Scheimpflug camera, and scanning-slit topography. The ACV was noninvasively measured by CAS-OCT. FINANCIAL DISCLOSURE(S) The authors have no proprietary or commercial interest in any materials discussed in this article.
Collapse
Affiliation(s)
- Shinichi Fukuda
- Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki, Japan.
| | | | | | | |
Collapse
|
39
|
Light transmission in the human cornea as a function of position across the ocular surface: theoretical and experimental aspects. Biophys J 2008; 95:5092-9. [PMID: 18790857 DOI: 10.1529/biophysj.108.132316] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This article investigates the theoretical basis for differences in visible light transmission through the human cornea as a function of distance from the center. Experimentally, transmission decreases approximately linearly up to 3 mm from the central axis, then quadratically beyond this. It is known that collagen fibril number density and collagen fibril radii change from the central region to the corneal periphery. We modeled, using the direct-summation-of-scattered-fields method, the effects these ultrastructural changes would be expected to have on light transmission, accounting for the increase in corneal thickness from center to edge. Fibril positions for the modeling were obtained from electron micrographs of human cornea. Theoretically, transmission remains fairly constant across the central cornea; then, as the fibril diameter increases, the predicted scattering increases. Interfibrillar spacing changes alter the refractive index ratio between matrix and fibril; this was modeled in our theoretical deductions. Fibril number density had a minimal effect on light propagation. Our theoretical deductions were in broad agreement with our experimental data. It is concluded that the reduced transparency in the peripheral stroma is primarily caused by changes in fibril radius and an increase in refractive index ratio between the fibril and the interfibrillar substance.
Collapse
|
40
|
Vincelette RL, Welch AJ, Thomas RJ, Rockwell BA, Lund DJ. Thermal lensing in ocular media exposed to continuous-wave near-infrared radiation: the 1150-1350-nm region. JOURNAL OF BIOMEDICAL OPTICS 2008; 13:054005. [PMID: 19021385 DOI: 10.1117/1.2978066] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Ocular damage threshold data remain sparse in the continuous wave (CW), near-infrared (NIR) radiation region save for the 1300-nm area that has been investigated in the past several decades. The 1300-nm ocular damage data have yielded unusual characteristics where CW retinal damage was observed in rabbit models, but never in nonhuman primate models. This paper reviews the existing 1300-nm ocular damage threshold data in terms of the fundamental criteria of an action spectrum to assist in explaining laser-tissue effects from near-infrared radiation in the eye. Reviewing the action spectrum criteria and existing NIR retinal lesion data lend evidence toward the significant presence of thermal lensing in ocular media affecting damage, a relatively unexplored mechanism of laser-tissue interaction.
Collapse
Affiliation(s)
- Rebecca L Vincelette
- University of Texas, Department of Biomedical Engineering, 1 University Station, C0800, Austin, Texas 78712, USA.
| | | | | | | | | |
Collapse
|
41
|
van de Kraats J, van Norren D. Optical density of the aging human ocular media in the visible and the UV. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2007; 24:1842-57. [PMID: 17728807 DOI: 10.1364/josaa.24.001842] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We analyzed the literature on the absorption in the young and aging human eye media. Five templates were derived to provide an adequate description of the spectra from 300 to 700 nm for the lens, cornea, aqueous, and vitreous. Two templates were found in all media. They stand for Rayleigh scatter and the absorbance of tryptophan. Three additional templates for the lens represent absorbance in kynurenine derivatives, such as 3-hydroxykynurenine glucoside (3HKG), and absorbance in two substances found at older age. Except for Rayleigh scatter, all templates have a Gaussian shape. Aging-trend functions were derived that show a linear slope on an age-squared scale. The result can be used to correct for media losses in visual perception tasks, in fundus reflectometry, and in studies on light damage.
Collapse
Affiliation(s)
- Jan van de Kraats
- Department of Ophthalmology, University Medical Center Utrecht, The Netherlands.
| | | |
Collapse
|
42
|
Dees C, Harkins J, Petersen MG, Fisher WG, Wachter EA. Treatment of Murine Cutaneous Melanoma with Near Infrared Light¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2002)0750296tomcmw2.0.co2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
43
|
Dada T, Sihota R, Gadia R, Aggarwal A, Mandal S, Gupta V. Comparison of anterior segment optical coherence tomography and ultrasound biomicroscopy for assessment of the anterior segment. J Cataract Refract Surg 2007; 33:837-40. [PMID: 17466858 DOI: 10.1016/j.jcrs.2007.01.021] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Accepted: 01/10/2007] [Indexed: 10/23/2022]
Abstract
PURPOSE To compare anterior segment parameters using quantitative imaging by anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM). SETTING Tertiary-care glaucoma research center. METHODS Sixty-three eyes of 63 subjects had anterior segment evaluation by AS-OCT (Visante-Zeiss) and UBM (Paradigm). Central corneal thickness (CCT), anterior chamber depth (ACD) (measured from the central corneal endothelium to the anterior lens capsule), and the peripheral iridocorneal angles (temporal and nasal) were assessed and compared. RESULTS There was an excellent correlation between AS-OCT and UBM measurements for the nasal angle (r = 0.84; P<.0001), temporal angle (r = 0.86; P<.0001), ACD (r = 0.97; P<.0001), and CCT (r = 0.91; P<.0001). There was no significant difference (paired t test) between the mean ACD, CCT, and angle parameters measured by AS-OCT or UBM. The mean values of the parameters measured by AS-OCT and UBM were, respectively, as follows: nasal angle, 26.25 degrees +/- 11.0 (SD) and 28.27 +/- 11.3 degrees (P = .3); temporal angle, 25.1 +/- 11.4 degrees and 28.3 +/- 13.5 degrees (P = .15); ACD, 2.85 +/- 0.5 mm and 2.78 +/- 0.5 mm (P = .2); and CCT, 512 +/- 46 microm and 502 +/- 46 microm (P = .25). The AS-OCT images showed sharper definition of the scleral spur than the UBM images. CONCLUSION Anterior segment optical coherence tomography and UBM can both be used for anterior segment measurements and yielded comparable results.
Collapse
Affiliation(s)
- Tanuj Dada
- Glaucoma Research Laboratory, Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
| | | | | | | | | | | |
Collapse
|
44
|
Sardar DK, Swanland GY, Yow RM, Thomas RJ, Tsin ATC. Optical properties of ocular tissues in the near infrared region. Lasers Med Sci 2006; 22:46-52. [PMID: 17143656 DOI: 10.1007/s10103-006-0421-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Accepted: 09/19/2006] [Indexed: 10/23/2022]
Abstract
Near infrared characterization of optical properties of aqueous humor and vitreous humor of healthy human and bovine eyes has been performed. The indices of refraction (n) of these ocular tissues were determined using a Michelson interferometer. The total diffuse reflection (R (d)) and total transmission (T (t)) measurements had been taken for individual ocular tissue by using a double-integrating sphere setup and infrared laser diodes. The inverse adding doubling (IAD) computational method based on the diffusion approximation and radiative transport theory was applied to the measured values of n, R (d), and T (t) to calculate the optical absorption and scattering coefficients of the human and bovine ocular tissues. The scattering anisotropy value was determined by iteratively running the IAD method program and a Monte Carlo simulation of light-tissue interaction until the minimum difference in experimental and computed value for T (t) was realized. A comparison between the optical characterization of human and bovine ocular samples was also made.
Collapse
Affiliation(s)
- Dhiraj K Sardar
- Department of Physics and Astronomy, The University of Texas at San Antonio, San Antonio, TX 78249-0697, USA.
| | | | | | | | | |
Collapse
|
45
|
Mihashi T, Hirohara Y, Bessho K, Maeda N, Oshika T, Fujikado T. Intensity analysis of Hartmann-Shack images in cataractous, keratoconic, and normal eyes to investigate light scattering. Jpn J Ophthalmol 2006; 50:323-333. [PMID: 16897216 DOI: 10.1007/s10384-006-0336-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Accepted: 01/23/2006] [Indexed: 12/01/2022]
Abstract
PURPOSE A clinical investigation of novel methods for evaluating light scattering using a Hartmann-Shack aberrometer. METHODS Aberrometry was performed on normal eyes (n=7; patient age, 26.7+/-2.5 years, mean+/-SD), eyes with keratoconus (n=22; patient age, 26.1+/-8.1 years), and eyes with cataract (n=17; patient age, 56.5+/-16.9 years) using a Hartmann-Shack wavefront aberrometer. We introduced two methods: (1) a contrast method, in which we calculated the inverse of contrast of the local images around 12 spots in a Hartmann-Shack image, and (2) a difference of point spread function (PSF) method, in which we analyzed the difference between the width of the PSF computed with aberration information and the width of the measured PSF, which contains both aberration and light scattering information. RESULTS The inverse contrast in cataractous eyes (5.04+/-3.06 inverse contrast units) was significantly larger than that in normal eyes (1.57+/-0.56) or keratoconic eyes (1.83+/-0.79). The difference of PSF in cataractous eyes (81.8+/-65.2 microm) was also significantly larger than that in normal eyes (9.3+/-4.3 microm) or keratoconic eyes (30.0+/-20.1 microm). The inverse contrast and the difference in the PSF were highly correlated (r=0.89, P<0.0001). CONCLUSIONS The two methods introduced here successfully distinguished cataractous eyes from normal and keratoconic eyes. After the results were analyzed by a discriminant analysis, the separation of the three categories proved to be excellent.
Collapse
Affiliation(s)
- Toshifumi Mihashi
- Department of Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan
- Technical Research Institute, Topcon Corporation, Tokyo, Japan
| | - Yoko Hirohara
- Department of Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan
- Technical Research Institute, Topcon Corporation, Tokyo, Japan
| | - Kenichiro Bessho
- Department of Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Naoyuki Maeda
- Department of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Tetsuro Oshika
- Department of Ophthalmology, University of Tsukuba, Tsukuba, Japan
| | - Takashi Fujikado
- Department of Visual Science, Osaka University Graduate School of Medicine, Osaka, Japan.
| |
Collapse
|
46
|
Kandulla J, Elsner H, Birngruber R, Brinkmann R. Noninvasive optoacoustic online retinal temperature determination during continuous-wave laser irradiation. JOURNAL OF BIOMEDICAL OPTICS 2006; 11:041111. [PMID: 16965139 DOI: 10.1117/1.2236301] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The therapeutic effect of most retinal laser treatments is initiated by a transient temperature increase. Although crucial to the effectiveness of the treatment, the temperature course is not exactly known due to individually different tissue properties. We develop an optoacoustic method to determine the retinal temperature increase in real time during continuous-wave (cw) laser irradiation, and perform temperature calculations to interpret the results exemplary for transpupillary thermotherapy (TTT). Porcine globes ex vivo and rabbit eyes in vivo are irradiated with a diode laser (lambda=810 nm, P< or =3 W, phi=2 mm) for 60 s. Simultaneously, pulses from a N2-laser pumped dye laser (lambda=500 nm, tau=3.5 ns, E approximately 5 microJ) are applied on the retina. Following its absorption, an ultrasonic pressure wave is emitted, which is detected by a transducer embedded in a contact lens. Using the previously measured temperature-dependent Gruneisen coefficient of chorioretinal tissue, a temperature raise in porcine eyes of 5.8 degrees C(Wcm2) after 60 s is observed and confirmed by simultaneous measurements with an inserted thermocouple. In a rabbit, we find 1.4 degrees C(Wcm2) with, and 2.2 degrees C(Wcm2) without perfusion at the same location. Coagulation of the rabbit's retina occurs at DeltaT=21 degrees C after 40 s. In conclusion, this optoacoustic method seems feasible for an in vivo real-time determination of temperature, opening the possibility for feedback control retinal laser treatments.
Collapse
Affiliation(s)
- Jochen Kandulla
- Universität zu Lübeck, Institut für Biomedizinische Optik, Peter-Monnik-Weg 4, D-23562 Lübeck, Germany.
| | | | | | | |
Collapse
|
47
|
Lei B, Yao G. Spectral attenuation of the mouse, rat, pig and human lenses from wavelengths 360 nm to 1020 nm. Exp Eye Res 2006; 83:610-4. [PMID: 16682025 DOI: 10.1016/j.exer.2006.02.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Revised: 02/03/2006] [Accepted: 02/08/2006] [Indexed: 11/17/2022]
Abstract
The transmission spectrum of the lens is essential to calculate irradiance at the surface of the retina. Although the mouse is a common model for ophthalmic research, there is little information on the transmission of the mouse lens. Attenuation by the lens is partly dependent on lens thickness; however, the attenuation coefficient is independent of lens thickness. In this study, we measured the attenuation coefficients of the albino and pigmented mouse lens as well as those of the rat, pig, and human lenses, and provide a composite equation that describes the attenuation coefficients in the ultraviolet and visible bandwidths (360-700 nm). In the near infrared region (700-1020 nm), water absorption must be included to explain the measurements.
Collapse
Affiliation(s)
- Bo Lei
- Department of Veterinary and Surgery, University of Missouri-Columbia, Columbia, MO 65211, USA
| | | |
Collapse
|
48
|
Borchert M, Lambert J, Sliney D. Validation of ICNIRP estimates of toxicity thresholds for NIR (785 nm) light in the retinas of pigmented rabbits. HEALTH PHYSICS 2006; 90:3-10. [PMID: 16340602 DOI: 10.1097/01.hp.0000175146.94650.4e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The International Commission on Non-Ionizing Radiation Protection (ICNIRP) established eye-safe exposure limits for laser light based on estimates of the 50% exposure dose (ED50) for retinal damage in animals. The ED50 has not been determined for continuous-wave near-infrared (NIR) light, as may be used in instruments for spectroscopic analysis of the eye. The purpose of this study is to determine the ED50 of 785-nm light delivered by a Raman spectroscopy instrument on the retinas of pigmented rabbits, and to compare that ED50 to the ICNIRP estimates. Light of varying power was focused into the anterior chambers of rabbits for 4, 20, or 300 s. Estimates of spot size on the retina were determined by modifying the schematic rabbit eye with actual axial length and refractive error measurements. Masked examiners determined retinal burns from fundus photographs and fluorescein angiograms made immediately after exposure and again 48-72 h later. Thirty-five of 86 exposed eyes had retinal burns. In 12 of these the burn was not visible until 48-72 h. In 6 the burn was visible on color photographs, but not on fluorescein angiography. The ED50 retinal power density from probit analysis was 14,513 mW cm(-2), 10,369 mW cm(-2), and 5,237 mW cm(-2) for 4-s, 20-s, and 300-s exposures, respectively. Thus, the ED50 for retinal burns from 785-nm light is approximately 7 and 7.5 times the ICNIRP permitted limits for 4- and 20-s exposures, and 5.6 times the limit for 300-s exposures. This is consistent with the ICNIRP intention to set power limits several times less than ED50.
Collapse
Affiliation(s)
- Mark Borchert
- Division of Ophthalmology, Childrens Hospital Los Angeles and Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | | | | |
Collapse
|
49
|
Abstract
PURPOSE To review the evolution in ocular temperature measurement during the last century and examine the advantages and applications of the latest noncontact techniques. The characteristics and source of ocular surface temperature are also discussed. METHODS The literature was reviewed with regard to progress in human thermometry techniques, the parallel development in ocular temperature measurement, the current use of infrared imaging, and the applications of ocular thermography. RESULTS It is widely acknowledged that the ability to measure ocular temperature accurately will increase the understanding of ocular physiology. There is a characteristic thermal profile across the anterior eye, in which the central area appears coolest. Ocular surface temperature is affected by many factors, including inflammation. In thermometry of the human eye, contact techniques have largely been superseded by infrared imaging, providing a noninvasive and potentially more accurate method of temperature measurement. Ocular thermography requires high resolution and frame rate: features found in the latest generation of cameras. Applications have included dry eye, contact lens wear, corneal sensitivity, and refractive surgery. CONCLUSIONS Interest in the temperature of the eye spans almost 130 years. It has been an area of research largely driven by prevailing technology. Current instrumentation offers the potential to measure ocular surface temperature with more accuracy, resolution, and speed than previously possible. The use of dynamic ocular thermography offers great opportunities for monitoring the temperature of the anterior eye.
Collapse
Affiliation(s)
- Christine Purslow
- Neurosciences Research Institute, School of Life and Health Sciences, Aston University, Aston Triangle, Birmingham, UK.
| | | |
Collapse
|
50
|
Lambert JL, Pelletier CC, Borchert M. Glucose determination in human aqueous humor with Raman spectroscopy. JOURNAL OF BIOMEDICAL OPTICS 2005; 10:031110. [PMID: 16229635 DOI: 10.1117/1.1914843] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
It has been suggested that spectroscopic analysis of the aqueous humor of the eye could be used to indirectly predict blood glucose levels in diabetics noninvasively. We have been investigating this potential using Raman spectroscopy in combination with partial least squares (PLS) analysis. We have determined that glucose at clinically relevant concentrations can be accurately predicted in human aqueous humor in vitro using a PLS model based on artificial aqueous humor. We have further determined that with proper instrument design, the light energy necessary to achieve clinically acceptable prediction of glucose does not damage the retinas of rabbits and can be delivered at powers below internationally acceptable safety limits. Herein we summarize our current results and address our strategies to improve instrument design.
Collapse
Affiliation(s)
- James L Lambert
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109-8099, USA.
| | | | | |
Collapse
|