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Böhm EW, Pfeiffer N, Wagner FM, Gericke A. Methods to measure blood flow and vascular reactivity in the retina. Front Med (Lausanne) 2023; 9:1069449. [PMID: 36714119 PMCID: PMC9877427 DOI: 10.3389/fmed.2022.1069449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023] Open
Abstract
Disturbances of retinal perfusion are involved in the onset and maintenance of several ocular diseases, including diabetic retinopathy, glaucoma, and retinal vascular occlusion. Hence, knowledge on ocular vascular anatomy and function is highly relevant for basic research studies and for clinical judgment and treatment. The retinal vasculature is composed of the superficial, intermediate, and deep vascular layer. Detection of changes in blood flow and vascular diameter especially in smaller vessels is essential to understand and to analyze vascular diseases. Several methods to evaluate blood flow regulation in the retina have been described so far, but no gold standard has been established. For highly reliable assessment of retinal blood flow, exact determination of vessel diameter is necessary. Several measurement methods have already been reported in humans. But for further analysis of retinal vascular diseases, studies in laboratory animals, including genetically modified mice, are important. As for mice, the small vessel size is challenging requiring devices with high optic resolution. In this review, we recapitulate different methods for retinal blood flow and vessel diameter measurement. Moreover, studies in humans and in experimental animals are described.
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Weigert G, Georgopoulos M, Buehl W, Maccora K, Aliyeva L, Steiner I, Schmidt‐Erfurth U, Sacu S. The influence of retinal oxygen saturation and choroidal volume on postoperative outcomes in patients with epiretinal membrane. Acta Ophthalmol 2022; 100:e743-e752. [PMID: 34396704 PMCID: PMC9291286 DOI: 10.1111/aos.14966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 06/17/2021] [Indexed: 11/28/2022]
Abstract
Purpose To investigate the effects of vitrectomy (Vy) with or without same time cataract surgery and membrane plus internal limiting membrane peeling (MP+ILMP) on retinal oxygenation and choroidal volume and their role on postoperative outcome. Methods Thirty‐two eyes were included in this prospective clinical study. All patients received 23 gauge Vy+MP+ILMP without endotamponade. Additional cataract surgery was performed in 14 patients. Follow‐up visits were scheduled at day 1, week 1, month 1 and month 3. At each visit, best corrected visual acuity (BCVA) using ETDRS charts (except at day 1), oxygenation of retinal vessels using the Oxymap T1, and optical coherence tomography (OCT, Heidelberg Spectralis) was performed. Results Mean BCVA increased significantly from 73 ± 11 letters to 77 ± 7 letters at month 3 (p = 0.02). Mean central retinal thickness (CRT) decreased from 456 ± 84 µm at baseline to 418±58µm (p = 0.01 baseline versus month 3). In the cataract surgery group, CRT was higher at month 3 than in the group without (400 ± 58 µm versus 441 ± 51 µm; p = 0.007). There was no statistically significant difference in choroidal volume or oxygenation of retinal vessels between groups (additional cataract surgery versus vitrectomy alone). Oxygenation of retinal arteries tended to decrease at day 1 followed by an increase, but the changes did not reach the level of significance (p = 0.29 baseline versus month 3). Oxygenation of retinal veins increased significantly (p = 0.02 baseline versus month 1; p = 0.04 baseline versus month 3, accordingly). There was a significant negative correlation (Spearman correlation coefficient rs = −0.35, p = 0.047) between visual acuity and oxygenation of retinal veins at month 3. No statistically significant correlation was found between CRT and oxygenation of neither retinal arteries nor veins. Choroidal volume (CV) of the central mm did not change significantly during the study period (baseline: 0.203 ± 0.04 mm3, median: 0.206, month 3: 0.205 ± 0.04 mm3, p = 0.54). There was no statistically significant effect of choroidal volume at baseline on postoperative clinical outcomes (change in BCVA estimate [95% CI]: 7 [−76; 90], p = 0.86; change in CRT: 147 [−577; 871], p = 0.68). Conclusion Oxygen saturation may affect the visual acuity outcome but not the CRT in patients after vitrectomy for epiretinal membrane. Choroidal thickness had no statistically significant influence on the study outcomes. Further studies are needed to evaluate if the measurement of retinal oxygenation may be helpful in the decision for surgery.
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Affiliation(s)
- Günther Weigert
- Department of Ophthalmology Medical University of Vienna Vienna Austria
| | | | - Wolf Buehl
- Department of Ophthalmology Medical University of Vienna Vienna Austria
- Vienna Clinical Trial Center Medical University of Vienna Vienna Austria
| | - Katia Maccora
- Department of Ophthalmology Medical University of Vienna Vienna Austria
- Vienna Clinical Trial Center Medical University of Vienna Vienna Austria
| | - Leyla Aliyeva
- Department of Ophthalmology Medical University of Vienna Vienna Austria
- Vienna Clinical Trial Center Medical University of Vienna Vienna Austria
| | - Irene Steiner
- CeMSIIS Center for Medical Statistics, Informatics and Intelligent Systems Section for Medical Statistics Medical University of Vienna Vienna Austria
| | | | - Stefan Sacu
- Department of Ophthalmology Medical University of Vienna Vienna Austria
- Vienna Clinical Trial Center Medical University of Vienna Vienna Austria
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Abstract
Similar to other organs, the retina relies on tightly regulated perfusion and oxygenation. Previous studies have demonstrated that retinal blood flow is affected in a variety of eye and systemic diseases, including diabetic retinopathy, age-related macular degeneration, and glaucoma. Although measurement of peripheral oxygen saturation has become a standard clinical measurement through the development of pulse oximetry, developing a noninvasive technique to measure retinal oxygen saturation has proven challenging, and retinal oximetry technology currently remains inadequate for reliable clinical use. Here, we review current strategies and approaches, as well as several newer technologies in development, and discuss the future of retinal oximetry.
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Affiliation(s)
- Anupam K Garg
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.,School of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Darren Knight
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Leonardo Lando
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA
| | - Daniel L Chao
- Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, CA, USA.,School of Medicine, University of California San Diego, La Jolla, CA, USA.,Janssen Research and Development, Raritan, NJ, USA
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Szegedi S, Dal‐Bianco P, Stögmann E, Traub‐Weidinger T, Rainer M, Masching A, Schmidl D, Werkmeister RM, Chua J, Schmetterer L, Garhöfer G. Anatomical and functional changes in the retina in patients with Alzheimer's disease and mild cognitive impairment. Acta Ophthalmol 2020; 98:e914-e921. [PMID: 32212415 PMCID: PMC7687124 DOI: 10.1111/aos.14419] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/04/2020] [Indexed: 01/14/2023]
Abstract
PURPOSE There is evidence that mild cognitive impairment (MCI) or Alzheimer's disease (AD) is accompanied by alterations in the retina. The current study was performed to investigate structural and functional changes in patients with systemic neurodegenerative disease. METHODS A total of 47 patients with either MCI or AD and 43 healthy age- and sex-matched control subjects were included. Inclusion criteria for MCI were abnormal memory function and a mini-mental state examination (MMSE) score >26 points, for patients with AD a diagnosis of probable AD of mild to moderate degree and an MMSE score in the range of 20-26. Retinal blood flow was measured using a Doppler optical coherence tomography (OCT) system. Retinal vessel diameter, oxygen saturation and flicker-induced vasodilatation were measured using a Vessel Analyzer. Retinal nerve fibre layer thickness (RNFLT) was assessed using an OCT system. RESULTS Global RNFLT was lower in patients compared to healthy controls (93.7 ± 12.8 µm versus 99.1 ± 9.0 µm, p = 0.02). The same was found in regards to retinal arterial blood flow, which was 9.3 ± 2.4 and 12.3 ± 3.2 μl/min in the patient and control groups, respectively (p < 0.001). Mean retinal arterial diameter was reduced in patients (76.0 ± 8.9 µm versus 80.6 ± 8.0 µm, p = 0.03). Arteriovenous difference in oxygen saturation was lower in patients (20.4 ± 5.1% versus 23.5 ± 4.0%, p < 0.01). No difference in the flicker response was observed. CONCLUSION In patients with MCI and AD, arteriovenous difference in oxygen saturation, retinal blood flow and arterial vessel diameter was reduced. No difference was found in flicker response between groups. This indicates alterations in retinal oxygen metabolism in patients with neurodegenerative disease.
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Affiliation(s)
- Stephan Szegedi
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - Peter Dal‐Bianco
- Department of NeurologyMedical University of ViennaViennaAustria
| | | | - Tatjana Traub‐Weidinger
- Division of Nuclear MedicineDepartment of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Michael Rainer
- Department of PsychiatrySocial and Medical Centre East – Danube HospitalViennaAustria
- Karl Landsteiner Institute for Memory and Alzheimer ResearchViennaAustria
| | - Andreas Masching
- Department of PsychiatrySocial and Medical Centre East – Danube HospitalViennaAustria
| | - Doreen Schmidl
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
| | - René M. Werkmeister
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
| | - Jacqueline Chua
- Singapore Eye Research InstituteSingapore National Eye CentreSingapore CitySingapore
- Ophthalmology and Visual Sciences Academic Clinical ProgramDuke‐NUS Medical SchoolSingapore CitySingapore
| | - Leopold Schmetterer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
- Center for Medical Physics and Biomedical EngineeringMedical University of ViennaViennaAustria
- Singapore Eye Research InstituteSingapore National Eye CentreSingapore CitySingapore
- Ophthalmology and Visual Sciences Academic Clinical ProgramDuke‐NUS Medical SchoolSingapore CitySingapore
- Lee Kong Chian School of MedicineNanyang Technological UniversitySingapore CitySingapore
- Institute of Molecular and Clinical OphthalmologyBaselSwitzerland
| | - Gerhard Garhöfer
- Department of Clinical PharmacologyMedical University of ViennaViennaAustria
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Szulc U, Dąbrowska E, Pieczyński J, Białkowski P, Narkiewicz K, Schmieder RE, Harazny J. How to measure retinal microperfusion in patients with arterial hypertension. Blood Press 2020; 30:4-19. [PMID: 32969283 DOI: 10.1080/08037051.2020.1823816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE Assessment and monitoring of changes in microcirculatory perfusion, perfusion dynamic, vessel structure and oxygenation is crucial in management of arterial hypertension. Constant search for non-invasive methods has led the clinical focus towards the vasculature of the retina, which offers a large opportunity to detect the early phase of the functional and structural changes in the arterial hypertension and can reflect changes in brain vasculature. We review all the available methods of retinal microcirculation measurements including angiography, oximetry, retinal vasculature assessment software, Optical Coherence Tomography Angiography, Adaptive Optics and Scanning Laser Doppler Flowmetry and their application in clinical research. MATERIALS AND METHODS To further analyse the applicability of described methods in hypertension research we performed a systematic search of the PubMed electronic database (April 2020). In our analysis, we included 111 articles in which at least one of described methods was used for assessment of microcirculation of the retina in hypertensive individuals. RESULTS Up to this point, the methods most commonly published in studies of retinal microcirculation in arterial hypertension were Scanning Laser Doppler Flowmetry followed shortly by Optical Coherence Tomography Angiography and retinal vasculature assessment software. CONCLUSIONS While none of described methods enables the simultaneous measurement of all microcirculatory parameters, certain techniques are widely used in arterial hypertension research, while others gain popularity in screening.
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Affiliation(s)
- Urszula Szulc
- Department of Human Physiology and Pathophysiology, University Warmia and Mazury, Olsztyn, Poland
| | - Edyta Dąbrowska
- Department of Hypertension and Diabetology, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland.,First Department of Cardiology, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Janusz Pieczyński
- Department of Ophthalmology, University Warmia and Mazury, Olsztyn, Poland
| | - Paweł Białkowski
- Department of Ophthalmology, Provincial Specialist Hospital, Olsztyn, Poland
| | - Krzysztof Narkiewicz
- Department of Hypertension and Diabetology, Faculty of Medicine, Medical University of Gdańsk, Gdańsk, Poland
| | - Roland E Schmieder
- Clinical Research Center, Department of Nephrology and Hypertensiology, University Erlangen-Nuremberg, Erlangen, Germany
| | - Joanna Harazny
- Department of Human Physiology and Pathophysiology, University Warmia and Mazury, Olsztyn, Poland.,Clinical Research Center, Department of Nephrology and Hypertensiology, University Erlangen-Nuremberg, Erlangen, Germany
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Nitzan M, Nitzan I, Arieli Y. The Various Oximetric Techniques Used for the Evaluation of Blood Oxygenation. SENSORS 2020; 20:s20174844. [PMID: 32867184 PMCID: PMC7506757 DOI: 10.3390/s20174844] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 12/12/2022]
Abstract
Adequate oxygen delivery to a tissue depends on sufficient oxygen content in arterial blood and blood flow to the tissue. Oximetry is a technique for the assessment of blood oxygenation by measurements of light transmission through the blood, which is based on the different absorption spectra of oxygenated and deoxygenated hemoglobin. Oxygen saturation in arterial blood provides information on the adequacy of respiration and is routinely measured in clinical settings, utilizing pulse oximetry. Oxygen saturation, in venous blood (SvO2) and in the entire blood in a tissue (StO2), is related to the blood supply to the tissue, and several oximetric techniques have been developed for their assessment. SvO2 can be measured non-invasively in the fingers, making use of modified pulse oximetry, and in the retina, using the modified Beer–Lambert Law. StO2 is measured in peripheral muscle and cerebral tissue by means of various modes of near infrared spectroscopy (NIRS), utilizing the relative transparency of infrared light in muscle and cerebral tissue. The primary problem of oximetry is the discrimination between absorption by hemoglobin and scattering by tissue elements in the attenuation measurement, and the various techniques developed for isolating the absorption effect are presented in the current review, with their limitations.
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Affiliation(s)
- Meir Nitzan
- Department of Physics/Electro-Optics Engineering, Jerusalem College of Technology, 21 Havaad Haleumi St., Jerusalem 91160, Israel;
- Correspondence:
| | - Itamar Nitzan
- Monash Newborn, Monash Children’s Hospital, Melbourne 3168, Australia;
- Department of Neonatology, Shaare Zedek Medical Center, Shmuel Bait St 12, Jerusalem 9103102, Israel
| | - Yoel Arieli
- Department of Physics/Electro-Optics Engineering, Jerusalem College of Technology, 21 Havaad Haleumi St., Jerusalem 91160, Israel;
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Heitmar R, Cubbidge RP. Retinal Vessel Oxygen Saturation Measurement Protocols and Their Agreement. Transl Vis Sci Technol 2020; 9:17. [PMID: 32821514 PMCID: PMC7409221 DOI: 10.1167/tvst.9.6.17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 03/04/2020] [Indexed: 12/01/2022] Open
Abstract
Purpose To assess agreement between different image sizes and analysis protocols for determination of retinal vessel oxygen saturation in the peripapillary retina of healthy individuals. Methods Retinal oximetry measurements were acquired from 87 healthy volunteers using the IMEDOS Systems oxygen module. The peripapillary retinal vessels were assessed in a concentric annulus around the optic nerve head. Single and average vessel comparisons were made at different image field sizes of 30° and 50°. Comparisons between images obtained at 30° and 50° were made in a subset of 47 of the 87 individuals. Results All subjects were normotensive and had normal intraocular pressures (9–16 mm Hg). Analyses of agreement between single vessel, averaged vessel, and between different size images were sought by Bland-Altman analyses, of which all yielded a low bias (<1% oxygen saturation). However, agreement between single vessels of consecutive images showed increased limits of agreement compared with saturation values calculated by averaging all or just the four major arcades of one image. Agreement between 30° and 50° images showed a similar bias as when comparing data obtained with the same camera angle setting but exhibited larger confidence intervals (arteries: bias = 0.21% [9.04/–8.62]%; veins: bias = 0.71% [14.82/–13.40]%). Conclusions Averaging methods yielded the best agreement; there was little difference in average arterial and venous oxygen saturation between protocols, which analyze all vessels versus the four largest vessels. The least agreement was found for single vessel measurements and comparisons between different camera angles. Translational Relevance Standardization of image capture protocols (same image size and undertaking a vessel averaging approach for oxygenation analysis) will enhance the detection of smaller physiological changes in eye disease.
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Affiliation(s)
- Rebekka Heitmar
- School of Life and Health Sciences, Aston University, Birmingham, UK
| | - Robert P Cubbidge
- School of Life and Health Sciences, Aston University, Birmingham, UK
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Retinal oximetry: Metabolic imaging for diseases of the retina and brain. Prog Retin Eye Res 2019; 70:1-22. [DOI: 10.1016/j.preteyeres.2019.04.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/27/2019] [Accepted: 04/10/2019] [Indexed: 12/20/2022]
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Yang Y, Yang D, Sun Y, Xie Y, Zhang Z, Li S, Wu S, Wang N. Retinal vessel oxygen saturation and vessel diameter in healthy individuals during high-altitude exposure. Acta Ophthalmol 2019; 97:279-286. [PMID: 30259682 DOI: 10.1111/aos.13897] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Accepted: 07/20/2018] [Indexed: 12/29/2022]
Abstract
PURPOSE To assess changes of retinal vessel oxygen saturation and vessel diameter in healthy individuals during high-altitude exposure. METHODS Retinal oxygen saturation and vessel diameter were obtained at sea level (SL, 40 m) and high altitude (HA, 3681 m) on 17 healthy individuals from Beijing (six males, 28.06 ± 8.06 years) using Oxymap T1 and then compared with 21 residents from Yushu (10 males, 28.63 ± 6.00 years). Systemic and ocular parameters were also measured before and after high-altitude exposure. Data were presented as mean ± SD and analysed using paired and independent Student t-test with significance accepted at p < 0.05. RESULTS Short-term high-altitude exposure of Beijing Group significantly affected all the systemic and ocular parameters, as well as retinal oxygen saturation and vessel diameter ranging from overall quadrant to different quadrants, other than retinal venous oxygen saturation and retinal arterial diameter. However, these changes were not evident in those permanently living at HA. Pearson's correlation analysis revealed correlations between retinal oxygen saturation and systemic and ocular parameters (all p < 0.05). The multivariate linear regression analysis indicated that retinal arterial oxygen saturation was significantly associated with arterial peripheral arterial oxygen saturation (SpO2 ) and subfoveal choroidal thickness. CONCLUSION Short-term exposure to HA induces retinal microcirculation disturbance and auto-regulatory response in healthy individuals, which is probably attributed to arterial SpO2 and endothelial dysfunction under hypoxic conditions.
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Affiliation(s)
- Yiquan Yang
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
- Beijing Institute of Ophthalmology Beijing Tongren Hospital Capital Medical University Beijing China
| | - Diya Yang
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
| | - Yunxiao Sun
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
- Beijing Institute of Ophthalmology Beijing Tongren Hospital Capital Medical University Beijing China
| | - Yuan Xie
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
- Beijing Institute of Ophthalmology Beijing Tongren Hospital Capital Medical University Beijing China
| | - Zheng Zhang
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
| | - Shuning Li
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
| | - Shizheng Wu
- Departments of Neurology The Qinghai Provincial People's Hospital Xining Qinghai China
| | - Ningli Wang
- Beijing Ophthalmology and Visual Sciences Key Laboratory Beijing Tongren Eye Center Beijing Tongren Hospital Capital Medical University Beijing China
- Beijing Institute of Ophthalmology Beijing Tongren Hospital Capital Medical University Beijing China
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Ishikawa S, Yoshinaga Y, Kantake D, Nakamura D, Yoshida N, Hisatomi T, Ikeda Y, Ishibashi T, Enaida H. Development of a novel noninvasive system for measurement and imaging of the arterial phase oxygen density ratio in the retinal microcirculation. Graefes Arch Clin Exp Ophthalmol 2018; 257:557-565. [PMID: 30569321 DOI: 10.1007/s00417-018-04211-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 11/25/2018] [Accepted: 12/04/2018] [Indexed: 11/28/2022] Open
Abstract
PURPOSE This study was conducted in order to develop a novel noninvasive system for measurement and imaging of the arterial oxygen density ratio (ODR) in the retinal microcirculation. METHODS We developed a system composed of two digital cameras with two different filters, which were attached to a fundus camera capable of simultaneously obtaining two images. Actual measurements were performed on healthy volunteer eyes (n = 61). A new algorithm for ODR measurement and pixel-level imaging of erythrocytes was constructed from these data. The algorithm was based on the morphological closing operation and the line convergence index filter. For system calibration, we compared and verified the ODR values in arterioles and venules that were specified in advance for 56 eyes with reproducibility. In 10 additional volunteers, ODR measurements and imaging of the arterial phase in the retinal microcirculation corresponding to changes in oxygen saturation of the peripheral arteries at normal breathing and breath holding were performed. RESULTS Estimation of incident light to erythrocytes and pixel-level ODR calculation were achieved using the algorithm. The mean ODR values of arterioles and venules were 0.77 ± 0.060 and 1.02 ± 0.067, respectively. It was possible to separate these regions, calibrate at the pixel level, and estimate the arterial phase. In each of the 10 volunteers, changes in the arterial phase ODR corresponding to changes in oxygen saturation of the peripheral arteries were observed before and after breath holding on ODR images. The mean ODR in 10 volunteers was increased by breath holding (p < 0.05). CONCLUSIONS We developed a basic system for arterial phase ODR measurement and imaging of the retinal microcirculation. With further validation and development, this may provide a useful tool for evaluating retinal oxygen metabolism in the retinal microcirculation.
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Affiliation(s)
- Shinichiro Ishikawa
- Department of Ophthalmology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan
| | - Yukiyasu Yoshinaga
- Graduate School of Design, Kyushu University, 4-9-1 Shiobaru, Fukuoka, Minami-ku, 815-8540, Japan
| | - Daichi Kantake
- Department of Ophthalmology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan
| | - Daisuke Nakamura
- Graduate School of Information Science and Electrical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Noriko Yoshida
- Section of Ophthalmology, Department of Medicine, Fukuoka Dental College, 2-15-1 Tamura, Sawara-ku, Fukuoka, 814-0193, Japan
| | - Toshio Hisatomi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Yasuhiro Ikeda
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | | | - Hiroshi Enaida
- Department of Ophthalmology, Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
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