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Fehler N, Lingenfelder C, Hessling M, Kupferschmid S. Retinal risk of endoillumination: A comparison of different ophthalmic illumination systems. J Fr Ophtalmol 2023; 46:377-387. [PMID: 36759248 DOI: 10.1016/j.jfo.2022.10.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 10/10/2022] [Indexed: 02/10/2023]
Abstract
OBJECTIVES In vitreoretinal surgery, there is always a conflict between bright illumination of the field of operation and retinal safety. This study aimed to investigate different light sources and light guides for their potential retinal risk due to bright illumination. METHODS Irradiances in the fovea of ex-vivo porcine eyes resulting from different light sources (halogen lamp, xenon lamp and LED) and light guides are investigated for varying distances between the illumination tip and the fovea. The results are examined with regard to their photochemical and thermal retinal hazard and the maximal exposure time. The examination is carried out with the maximum intensity setting of each light source and with normalization to its brightness. MAIN RESULTS With decreasing distance of the tip of the light source, the retinal hazard increases. The photochemical and thermal retinal hazard at maximum brightness are smallest for the halogen lamp, next for the xenon lamp and highest for the LED. Thus, the exposition time is the longest for the halogen lamp followed by the xenon lamp and the LED. Normalizing the results to the same brightness the maximum exposition time is nearly the same for xenon lamp and LED, but still higher in case of the halogen lamp. CONCLUSIONS The choice of the most suitable lamp and illumination fiber depends on the intensity and spectral distribution of the illumination system. Concerning brightness, xenon and LED lamp are relatively harmless, but the surgeon should avoid the maximum device intensity.
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Affiliation(s)
- N Fehler
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, 89081 Ulm, Germany.
| | - C Lingenfelder
- Pharmpur GmbH, Messerschmittring 33, 86343 Königsbrunn, Germany
| | - M Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, 89081 Ulm, Germany
| | - S Kupferschmid
- Clinic of Ophthalmology, Bundeswehrkrankenhaus Ulm, Oberer Eselsberg 40, 89081 Ulm, Germany
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Brandl A, Egner C, Reisser U, Lingenfelder C, Schleip R. Influence of high-energy laser therapy to the patellar tendon on its ligamentous microcirculation: An experimental intervention study. PLoS One 2023; 18:e0275883. [PMID: 36972259 PMCID: PMC10042339 DOI: 10.1371/journal.pone.0275883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Accepted: 03/07/2023] [Indexed: 03/29/2023] Open
Abstract
Laser therapeutic applications, such as the use of high energy lasers (HILT), are widely used in physical therapy, but basic studies on the mechanisms of action of HILT on tendinous/ligamentous tissue are largely lacking. The aim of this study was to investigate microcirculatory changes of the patellar tendon by HILT. 21 healthy volunteers were included in the present investigation. Before and after HILT, as well as 10 minutes later, the microcirculation was measured by noninvasive laser Doppler and white light spectroscopy (O2C device). Tissue temperature was recorded at the measurement time points using thermography. Blood flow increased significantly by 86.38 arbitrary units (AU; p < 0.001) after the intervention and by 25.76 AU (p < 0.001) at follow-up. Oxygen saturation increased by 20.14% (p < 0.001) and 13.48%, respectively (p < 0.001), whereas relative hemoglobin decreased by 6.67 AU and 7.90 AU, respectively. Tendon temperature increased by 9.45° and 1.94° Celsius, respectively. Acceleration of blood flow by improving the flow properties of erythrocytes and platelets may have caused the results. HILT could be a therapeutic perspective for tendon pathologies with impaired microcirculation, although further studies are needed to validate the experimental results.
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Affiliation(s)
- Andreas Brandl
- Faculty for Psychology and Human Movement Science, Department of Sports Medicine, Institute for Human Movement Science, University of Hamburg, Hamburg, Germany
- DIPLOMA Hochschule, Bad Sooden-Allendorf, Germany
| | | | | | | | - Robert Schleip
- DIPLOMA Hochschule, Bad Sooden-Allendorf, Germany
- Department of Sport and Health Sciences, Conservative and Rehabilitative Orthopedics, Technical University of Munich, Munich, Germany
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Fehler N, Lingenfelder C, Kupferschmid S, Hessling M. Determination of the intraocular irradiance and potential retinal hazards at various positions in the eye during transscleral equatorial illumination for different applied pressures. Z Med Phys 2022:S0939-3889(22)00122-2. [PMID: 36513575 DOI: 10.1016/j.zemedi.2022.11.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/25/2022] [Accepted: 11/15/2022] [Indexed: 12/14/2022]
Abstract
PURPOSE With diaphanoscopic illumination of the eye, the intensity of light entering its interior depends on the transmission properties of the eyewall. Light that passes through the eyewall can cause damage to the retina. Therefore, in this study, the intraocular irradiances are determined at different positions on the retina, directly behind the illuminated eyewall, the opposite eyewall and near the macula of ex-vivo porcine eyes. These irradiances are examined for their dependence on the pressure applied on the eyewall with the illuminating fiber and for the influence of the pigmentation of the eye. METHODS In total 221 ex-vivo porcine eyes were investigated. For transscleral illumination an illumination fiber with a diffusing adapter cap is pressed against the equatorial eyewall. The illumination fiber is pressed onto the eye and the pressure is measured in the anterior chamber. Three different pressures are applied, 23, 78 and 132 mmHg. A detection fiber with diffusing fiber tip is inserted into the eye at the desired position. The eyes were divided in groups with high and less pigmentation to investigate the influence of the pigmentation on the intraocular irradiance. RESULTS The intraocular irradiances Eintra increases for various increasing applied pressures with the illumination fiber on the eyewall and for various positions inside the eye. With this the irradiances weighted with the photochemical and thermal hazard weighting function, EA-R and EVIR-R, also increases. Differences in Eintra, EA-R and EVIR-R could be found for different pigmented eyes as these values are higher for less pigmented eyes than for strong pigmented ones. CONCLUSION The hazard to the retina during diaphanoscopic illumination of the eye depends on how strong the surgeon presses the illumination fiber on the eyewall. Depending on the applied pressure and the measuring position in the eye, the specified limit for the photochemical hazard to the retina is partly exceeded. The pigmentation of the eye also plays a role. The irradiance in less pigmented eyes appears to be higher than in strongly pigmented eyes. Because of this, the surgeon should be able to adjust the intensity of the light source to the color of the patient's eye.
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Affiliation(s)
- Nicole Fehler
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany.
| | | | | | - Martin Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany.
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Sieber N, Lingenfelder C, Götz M, Heine P, Lichtner L, Hessling M. Vitrectome with Integrated LED Illumination: Development and Testing. Current Directions in Biomedical Engineering 2021. [DOI: 10.1515/cdbme-2021-2217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Background: In current vitrectomy, the surgeon guides the vitrectome and a rigid fiber light guide with one hand each. It would be desirable to have a free hand for other surgical instruments and maneuvers. Methods: In the feasibility study presented here, a 20 gauge vitrectome is equipped with a miniature white LED that could eliminate the need for the separate light guide and therefore free one hand. The functionality of the system is proved in a ping-pong ball filled with agar and an ex-vivo porcine eye. Results: The brightness of the approach appears to be sufficient without any realistic phototoxic retinal hazard while the functionality of the vitrectome, in combination with the LED, is still given. Conclusion: The combination of a 20 gauge vitrectome with a LED illumination unit was successfully tested. The approach can be transferred to small vitrectomes in the future
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Affiliation(s)
- Nicole Sieber
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, 89081 Ulm , Germany
| | | | - Madeleine Götz
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm , Germany
| | - Pauline Heine
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm , Germany
| | - Leonie Lichtner
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm , Germany
| | - Martin Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm , Germany
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Busshardt J, Sieber N, Koelbl P, Lingenfelder C, Hessling M. Development and first assessment of a RGBW-LED diaphanoscope. Ophthalmol J 2021. [DOI: 10.5603/oj.2021.0020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Sieber N, Kölbl P, Lingenfelder C, Stucke-Straub K, Kupferschmid S, Hessling M. Measurement of the retinal irradiation exposure during diaphanoscopic illumination. Current Directions in Biomedical Engineering 2020. [DOI: 10.1515/cdbme-2020-3070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
For the visualisation of the intraocular space it is essential to illuminate the inside of the eye. One illumination approach is diaphanoscopy, in which the light of an extraocular source is transmitted through the tissue layers of the eyewall. The transmission properties of these tissues and their irradiation load depend on applied diaphanoscope contact pressure. However, excessive illumination can lead to irreversible photochemical and thermal damage to the retina. In diaphanoscopic illumination, the retina is particularly at risk due to its proximity to the light source. Therefore, the photochemical and thermal retinal hazards, resulting from direct transmitted light through the eyewall, are determined for different applied pressures of the diaphanoscope on the eye (15, 65 and 115 kPa). The study is performed on porcine eyes with different pigmentation. So, the difference in intraocular irradiance, photochemical and thermal hazards, as well as the maximal exposure time is also examined for different pigmentations. For less pigmented eyes the irradiance inside the eye, the photochemical and the thermal hazard are higher than for higher pigmented eyes. The values also become significantly higher for increasing applied pressure with the diaphanoscope but do not exceed given limits in the standard DIN EN ISO 15004-2: 2014.
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Affiliation(s)
- Nicole Sieber
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, 89081 Ulm , Germany
| | - Phillip Kölbl
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm , Germany
| | | | - Kathrin Stucke-Straub
- Department of Mathematics, Natural and Economic Sciences, Ulm University of Applied Sciences, Ulm , Germany
| | | | - Martin Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm , Germany
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Hessling M, Hoenes K, Lingenfelder C. Selection of parameters for thermal coronavirus inactivation - a data-based recommendation. GMS Hyg Infect Control 2020; 15:Doc16. [PMID: 32733781 PMCID: PMC7373095 DOI: 10.3205/dgkh000351] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Background: Healthcare workers and large parts of the population are currently using personal protective equipment, such as face masks, to avoid infections with the novel coronavirus SARS-CoV-2. This equipment must be sterilized as gently as possible before reuse. One possibility is thermal inactivation, but professional autoclaves with their high temperatures are often not available or suitable. If the inactivation period is long enough, coronavirus inactivation can also be carried out at relatively low temperatures. The required duration was determined in this study. Material and methods: Data from published thermal inactivation studies on coronaviruses were applied to determine the temperature dependence of the rate constant k(T) for each coronavirus by employing Arrhenius models. Results: The data obtained exhibit large variations, which appear to be at least partially caused by different sample properties. Samples with high protein content or samples in dry air sometimes seem to be more difficult to inactivate. Apart from this, the Arrhenius models describe the thermal inactivation properties well and SARS-CoV and SARS-CoV-2 can even be represented by a combined model. Furthermore, the available data suggest that all samples, including critical ones, can be mathematically included by a worst-case Arrhenius model. Conclusion: Coronaviruses can already be inactivated at relatively low temperatures. For most samples, application times of approximately 32.5, 3.7, and 0.5 minutes will be sufficient at 60°C, 80°C, and 100°C, respectively, for a 5 log-reduction. For difficult conditions, the worst-case model provides significantly longer application times of 490, 55, and 8 minutes for the temperatures mentioned.
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Affiliation(s)
- Martin Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
| | - Katharina Hoenes
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
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Lingenfelder C, Kampmeier J, Russ D, Wittig R, Diener C, Werner JU. [Depth Effect of Cold Atmospheric Pressure Plasma in Keratitis Therapy: A Corneal Stroma Tissue Model]. Klin Monbl Augenheilkd 2020; 237:1087-1092. [PMID: 32434228 DOI: 10.1055/a-1142-6442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The incidence of microbial keratitis has been increasing and is now 28 cases/100,000 inhabitants; this may be due to the more frequent use of contact lenses. Keratitis can lead to visual impairment and in severe cases with endophthalmitis to enucleation of the affected eye. As microorganisms are becoming more resistant to antibiotic therapy, there is a need for new therapeutic strategies. Cold atmospheric pressure plasma has already been successfully used to disinfect surfaces. This study investigates the efficacy of cold atmospheric pressure plasma against Escherichia coli in a depth-resolved corneal stroma tissue model.
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Affiliation(s)
| | | | - Detlef Russ
- Institut für Lasertechnologien in der Medizin und Messtechnik an der Universität Ulm
| | - Rainer Wittig
- Institut für Lasertechnologien in der Medizin und Messtechnik an der Universität Ulm
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Heßling M, Hönes K, Vatter P, Lingenfelder C. Ultraviolet irradiation doses for coronavirus inactivation - review and analysis of coronavirus photoinactivation studies. GMS Hyg Infect Control 2020; 15:Doc08. [PMID: 32547908 PMCID: PMC7273323 DOI: 10.3205/dgkh000343] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Background: To slow the increasing global spread of the SARS-CoV-2 virus, appropriate disinfection techniques are required. Ultraviolet radiation (UV) has a well-known antiviral effect, but measurements on the radiation dose necessary to inactivate SARS-CoV-2 have not been published so far. Methods: Coronavirus inactivation experiments with ultraviolet light performed in the past were evaluated to determine the UV radiation dose required for a 90% virus reduction. This analysis is based on the fact that all coronaviruses have a similar structure and similar RNA strand length. Results: The available data reveals large variations, which are apparently not caused by the coronaviruses but by the experimental conditions selected. If these are excluded as far as possible, it appears that coronaviruses are very UV sensitive. The upper limit determined for the log-reduction dose (90% reduction) is approximately 10.6 mJ/cm2 (median), while the true value is probably only 3.7 mJ/cm2 (median). Conclusion: Since coronaviruses do not differ structurally to any great exent, the SARS-CoV-2 virus – as well as possible future mutations – will very likely be highly UV sensitive, so that common UV disinfection procedures will inactivate the new SARS-CoV-2 virus without any further modification.
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Affiliation(s)
- Martin Heßling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
| | - Katharina Hönes
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
| | - Petra Vatter
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
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Koelbl PS, Sieber N, Lingenfelder C, Koch FHJ, Deuchler S, Hessling M. Pressure dependent direct transtissue transmission of eyewall, sclera and vitreous body in the range of 350-1050nm. Z Med Phys 2020; 30:201-210. [PMID: 32143979 DOI: 10.1016/j.zemedi.2020.02.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 02/03/2020] [Accepted: 02/10/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE For transscleral application of optical radiation or light to the eye, it is important to know the transmission and absorbance of the tissue layers of the eyewall. The impact of photochemical energy to the retina located directly at the point of contact with the radiation emitter must be considered as well as the absorbance in choroid and retina. Therefore, the direct transmission of ex vivo porcine eyewalls and vitreous body were measured in this study. METHODS At ex vivo porcine eyes (N=221) pressure dependent transmission measurements were performed with a pressure inducing setup. Pressure and wavelength dependent direct transmission of eyewall and vitreous body of porcine eyes were described for different applied pressures (23mmHg, 78mmHg and 132mmHg). The transmissions were investigated within the spectral range of 350-1050nm. In addition to the complete eyewall transmission measurements, the transmission of sclera, vitreous body and water was measured individually and the transmission of retina and choroid was calculated. RESULTS With increasing wavelength and pressure, a significant transmission increase of the eyewall could be achieved (p<0.05). At 400nm and 132mmHg the transmission raised to 0.10%. At 1050nm it increased up to a value of 12.22%. In the visible spectrum, the direct transmission was always below 3.17%. The differences in eyewall transmission of eyes with different iris colors were significant at low pressure. With increasing pressure, the effect strength decreased and the differences lost their significance. CONCLUSIONS The pressure and wavelength dependent direct transmission of the eyewall and the vitreous body significantly increased with increasing pressure. This results are benefical for technical and clinical safety, research and development of illumination devices. It is necessary to know the intraocular brightness in the eye during diaphanoscopy, photocoagulation application to determine hazards.
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Affiliation(s)
- Philipp S Koelbl
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, D-89081 Ulm, Germany
| | - Nicole Sieber
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, D-89081 Ulm, Germany
| | | | - Frank H J Koch
- Clinic of Ophthalmology, Goethe University, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany
| | - Svenja Deuchler
- Clinic of Ophthalmology, Goethe University, Theodor-Stern-Kai 7, D-60590 Frankfurt, Germany
| | - Martin Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, D-89081 Ulm, Germany.
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Koelbl PS, Hessling M, Lingenfelder C, Kupferschmid S. Higher Risk of Light-Induced Retinal Damage Due to Increase of Intraocular Irradiance by Endoillumination. Ophthalmol Ther 2018; 8:41-50. [PMID: 30560504 PMCID: PMC6393251 DOI: 10.1007/s40123-018-0157-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Indexed: 12/05/2022] Open
Abstract
Introduction All applied illumination systems are validated according to a standard that measures in an experimental setup the direct radiation intensity on a surface in an aqueous solution, not involving an eyeball. Due to various factors, multiple intraocular light-tissue interactions could occur and lead to retinal irradiation intensities that are higher than the irradiation caused by direct illumination. The aim of this work is to investigate the hypothesis that intraocular and technical reference irradiance is different. Methods Using an illumination system and a calibrated optical fiber, the irradiance in porcine eyes was measured at the posterior pole (macula) and compared with reference measurements. We compared two endoilluminators (spotlight and wide-angle) at a total of nine porcine eyes with a brown iris and five porcine eyes with a blue iris. Results The intraocular irradiance was always significantly higher compared to reference measurements (p < 0.001). Between eyes with a blue or brown iris, no significant difference was observed. Conclusion A significantly higher irradiance could be measured compared to a reference measurement with the same illumination setup. The intraocular illumination increased between 30 and 60%, dependent on the distance of the distal end of the light fiber (4–12-mm distance to the retina). This leads to the assumption that the so far allowed “safe” exposure times for illumination systems are overestimated and the potential hazard to the retina is higher.
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Affiliation(s)
- Philipp S Koelbl
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, 89081, Ulm, Germany. .,Medical Faculty, Ulm University, Albert-Einstein-Allee 7, 89081, Ulm, Germany.
| | - Martin Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, 89081, Ulm, Germany
| | | | - Sebastian Kupferschmid
- Clinic of Ophthalmology, Bundeswehrkrankenhaus Ulm, Oberer Eselsberg 40, 89081, Ulm, Germany
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12
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Koelbl PS, Werner JU, Enders C, Lingenfelder C, Koch FHJ, Hessling M. Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications. Ophthalmic Res 2018; 61:159-167. [PMID: 29852494 DOI: 10.1159/000488493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 03/14/2018] [Indexed: 11/19/2022]
Abstract
PURPOSE Surgical or diagnostic procedures are often accompanied by a short-term increase in intraocular pressure (IOP). A short-term increase in IOP can occur during refractive procedures, vitreoretinal surgery, transillumination, photocoagulation, or cryocoagulation. A porcine eye model was chosen (n = 89) to compile comparable study data and to de termine correlations between the force induced and the resulting intraocular pressure while excluding the effect of surgeons. METHODS The IOP was measured in the anterior chamber. IOP changes were induced by applying an external force and measured when using a cannula, trocar, and cryocoagulation (n = 32), and correlations between force and resulting IOP were assessed (n = 57). RESULTS A correlation was noted between the force induced and the IOP increase, which showed a linear dependency. The insertion of a 29-G cannula caused a mean ΔIOP value of 49.1 ± 2.9 mm Hg and an external force of 0.76 N, and that of a 23-G trocar 344.4 ± 5.9 mm Hg and 6.09 N, respectively. The rise in IOP during a simulated cryocoagulation reached values between 57.3 ± 14.8 mm Hg (cryoprobe tip diameter: 0.9 mm) and 130.3 ± 2.9 mm Hg (cryoprobe tip diameter: 7.0 mm). CONCLUSION The values of the forces applied can be converted into the resulting IOP based on the specific action. Surgical or diagnostic procedures should, therefore, be evaluated with regard to preexisting pathologies, such as glaucoma.
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Affiliation(s)
- Philipp Simon Koelbl
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany,
| | | | | | | | - Frank H J Koch
- Clinic of Ophthalmology, Goethe University, Frankfurt am Main, Germany
| | - Martin Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
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Koelbl PS, Lingenfelder C, Spraul CW, Kampmeier J, Koch FH, Kim YK, Hessling M. An intraocular micro light-emitting diode device for endo-illumination during pars plana vitrectomy. Eur J Ophthalmol 2018; 29:75-81. [PMID: 29592777 DOI: 10.1177/1120672118757618] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE: Development of a new, fiber-free, single-use endo-illuminator for pars plana vitrectomy as a replacement for fiber-based systems with external light sources. The hand-guided intraocularly placed white micro light-emitting diode is evaluated for its illumination properties and potential photochemical and thermal hazards. METHODS: A micro light-emitting diode was used to develop a single-use intraocular illumination system. The light-source-on-tip device was implemented in a prototype with 23G trocar compatible outer diameter of 0.6 mm. The experimental testing was performed on porcine eyes. All calculations of possible photochemical and thermal hazards during the application of the intraocular micro light-emitting diode were calculated according to DIN EN ISO 15007-2: 2014. RESULTS: The endo-illuminator generated a homogeneous and bright illumination of the intraocular space. The color impression was physiologic and natural. Contrary to initial apprehension, the possible risk caused by inserting a light-emitting diode into the intraocular vitreous was much smaller when compared to conventional fiber-based illumination systems. The photochemical and thermal hazards allowed a continuous exposure time to the retina of at least 4.7 h. CONCLUSION: This first intraocular light source showed that a light-emitting diode can be introduced into the eye. The system can be built as single-use illumination system. This light-source-on-tip light-emitting diode-endo-illumination combines a chandelier wide-angle illumination with an adjustable endo-illuminator.
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Affiliation(s)
- Philipp S Koelbl
- 1 Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
| | | | | | | | - Frank Hj Koch
- 5 Clinic of Ophthalmology, Goethe University Frankfurt, Frankfurt, Germany
| | | | - Martin Hessling
- 1 Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Ulm, Germany
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14
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Thaller M, Böhm H, Lingenfelder C, Geiger F. [Hyaluronic acid gels for pressure regulation in glaucoma treatment]. Ophthalmologe 2017; 115:195-201. [PMID: 29119227 DOI: 10.1007/s00347-017-0602-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND The increasing numbers of glaucoma patients and complications occuring during treatment, such as restenosis and hypotony, require new treatment options to prevent blindness in patients. Therefore, the abovementioned problems should be solved to prolong the lifetime of implants and to prevent repeated surgery. OBJECTIVE Can a novel stent with hyaluronic acid hydrogels (HA gel) as a functional unit be used to regulate pressure in glaucoma therapy in the long term? MATERIAL AND METHODS Model stents were filled with HA gels and it was investigated if these could regulate the pressure and what the underlying mechanism is. RESULTS The results of the investigations showed that the HA gel inside the stent functions as a pressure valve. Under certain equilibrium pressures the HA gel closes the stent and therefore retains the fluid. At a certain overpressure the HA gel enables the fluid to be released and leads to a self-regulated adjustment of the equilibrium pressure. DISCUSSION The next step will involve miniaturization of the stents. Experiments will then show if the valve function will also work in the dimensions necessary for an eye implant and if the current problem of hypotension in glaucoma therapy can be solved.
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Affiliation(s)
- M Thaller
- Abt. Zelluläre Biophysik, Max-Planck-Institut für medizinische Forschung, Jahnstr. 29, 69120, Heidelberg, Deutschland
- Biophysikalische Chemie, Universität Heidelberg, INF 253, 69120, Heidelberg, Deutschland
| | - H Böhm
- Abt. Zelluläre Biophysik, Max-Planck-Institut für medizinische Forschung, Jahnstr. 29, 69120, Heidelberg, Deutschland
- Biophysikalische Chemie, Universität Heidelberg, INF 253, 69120, Heidelberg, Deutschland
| | - C Lingenfelder
- Pharmpur GmbH, Messerschmittring 33, 86343, Königsbrunn, Deutschland
| | - F Geiger
- Abt. Zelluläre Biophysik, Max-Planck-Institut für medizinische Forschung, Jahnstr. 29, 69120, Heidelberg, Deutschland.
- Biophysikalische Chemie, Universität Heidelberg, INF 253, 69120, Heidelberg, Deutschland.
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Koelbl PS, Klante P, Koch F, Lingenfelder C, Werner JU, Enders C, Hessling M. Location and pressure dependent transmission of human and porcine sclera: an anterior to posterior examination. Graefes Arch Clin Exp Ophthalmol 2017; 255:2185-2198. [PMID: 28779364 DOI: 10.1007/s00417-017-3758-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 07/17/2017] [Indexed: 10/19/2022] Open
Abstract
PURPOSE For diaphanoscopy or transscleral laser applications, the transmission of the sclera is an essential property. The study aimed to determine the pressure dependent transmission of human sclera from anterior to posterior. METHODS Pressure dependent transmission measurements were performed by a pressure inducing setup at the range of 60-2058 kPa. The transmissions were measured within spectral range of 350-1100 nm. Specimens of human sclera were taken from corneo-scleral transplants. Those compounds were obtained at pars plicata residual sclera tissue. For an anterior to posterior examination of transmission, samples were taken from halved eye globes, which were formerly fixed in formalin. RESULTS The pressure dependent transmission increased with rising load at all measured wavelengths for human sclera samples. The highest increase was observed for short wavelengths. With rising pressure, the increase of transmission aimed for a steady state. This behavior was fitted by a limited growing function. With an inducing burden of 2058 kPa, the steady state was already reached and exhibited an increase in transmission factor of 4.1 at 400 nm and 1.8 at 1000 nm. The anterior to posterior measurements of human sclera fixed in formalin were not corresponding to the results of the other human samples. For the porcine samples, the transmission increased from anterior to the equator of the eye globe. Further posterior the transmission decreased and rose again to N. opticus. With rising pressure, the transmission increased at all wavelengths and all locations. Posterior from the equator, with higher pressure the transmission became superior compared to anterior. CONCLUSIONS The results of human sclera fixed in formalin could be related to formalin-induced cross-linking between the collagen fibers. Because of doubt about the physiological behavior of formalin-fixed samples, formalin-free porcine postmortem eye globes were also probed having a very similar thickness and histological structure as human sclera, so the results could be set in relation to human probes. These results can now be used to create an eye-map to determine maximum possible retina irradiation or illumination durations for transscleral applications in eye surgery.
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Affiliation(s)
- Philipp Simon Koelbl
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, D-89081, Ulm, Germany.
| | - Pia Klante
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, D-89081, Ulm, Germany
| | - Frank Koch
- Clinic of Ophthalmology, Goethe University, Theodor-Stern-Kai 7, D-60590, Frankfurt, Germany
| | | | - Jens Ulrich Werner
- Department of Ophthalmology, University of Ulm, Prittwitzstrasse 43, D-89075, Ulm, Germany
| | - Christian Enders
- Department of Ophthalmology, University of Ulm, Prittwitzstrasse 43, D-89075, Ulm, Germany
| | - Martin Hessling
- Institute of Medical Engineering and Mechatronics, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, D-89081, Ulm, Germany
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Kölbl PS, Lindner C, Lingenfelder C, Deuchler S, Singh P, Koch FHJ, Heßling M. [Fiberless miniature chandelier LED endoilluminator for pars plana vitrectomy]. Ophthalmologe 2015; 113:47-51. [PMID: 26025297 DOI: 10.1007/s00347-015-0050-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Currently available chandelier endoilluminators for pars plana vitrectomy consist of conventional optical fibers coupled to a light source. The light probes of these fibers now provide wide emittance angles but it is still often not possible to illuminate the whole intraocular space via just one incision. Therefore, several light probes or additional handheld endoilluminators have to be used simultaneously or the lights have to be repositioned during surgery. OBJECTIVE The presented prototype of a fiberless chandelier light-emitting diode (LED) endoilluminator aims at illuminating the whole intraocular space with just one incision while reducing the risk of harming the retina. MATERIAL AND METHODS The light source is a white LED with a conical tip that allows stable fixation within an incision. The physical properties of these LEDs were determined and used for calculating the relevant irradiance to assess the risk of causing harm to the eye. The illumination of the intraocular space was investigated using porcine eyes. RESULTS The illumination of porcine eyes with the modified LEDs was bright and homogeneous. Measurements and subsequent calculations proved that the expected thermal load and photochemical hazard were very low for human eyes. CONCLUSION The hitherto existing experimental results on porcine eyes and the theoretical considerations on human eyes were found to be positive; therefore, it is expected that this new fiberless chandelier LED endoilluminator will prove to be advantageous for human patients. It promises a reduced number of incisions with a simplified handling and need to add handheld light sources only if minimal intensity oblique illumination is helpful together with the chandelier illumination. This contributes to a significant reduction of phototoxicity risks and additionally there is a chance for a cost reduction because expensive xenon or mercury lamps are no longer necessary. These expectations have to be verified by further studies on human eyes.
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Affiliation(s)
- P S Kölbl
- Institut für Medizintechnik und Mechatronik, Hochschule Ulm, Albert-Einstein-Allee 55, 89081, Ulm, Deutschland
| | - C Lindner
- Alamedics GmbH & Co. KG, Dornstadt, Deutschland
| | | | - S Deuchler
- Klinik für Augenheilkunde, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt, Deutschland
| | - P Singh
- Klinik für Augenheilkunde, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt, Deutschland
| | - F H J Koch
- Klinik für Augenheilkunde, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt, Deutschland
| | - M Heßling
- Institut für Medizintechnik und Mechatronik, Hochschule Ulm, Albert-Einstein-Allee 55, 89081, Ulm, Deutschland.
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Kölbl PS, Lindner C, Lingenfelder C, Deuchler S, Singh P, Koch F, Hessling M. An extraocular non-invasive transscleral LED-endoilluminator for eye speculum integration. Graefes Arch Clin Exp Ophthalmol 2015; 253:1529-35. [PMID: 25957763 DOI: 10.1007/s00417-015-3036-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 04/01/2015] [Accepted: 04/22/2015] [Indexed: 10/23/2022] Open
Abstract
PURPOSE Conventional chandelier-endoilluminators used for pars-plana vitrectomy consist of a light-emitting tip attached to an optical fibre. The tip requires introduction into the ocular space through an incision. To achieve complete illumination of the intraocular space, the introduction of more than just one tip is sometimes necessary. An extraocular vitreoretinal LED-endoilluminator discussed in this paper represents a new approach to illuminate the intraocular space. The light source is integrated into a speculum and firmly apposed to the sclera. This approach offers the advantage of effectively illuminating the interior of the eye even though the procedure is non-invasive. Furthermore, this approach significantly reduces the risk of damage to the retina by phototoxic effects. METHODS A round white LED was used as a light source. By integrating the light source into a speculum, the LED was firmly held against the sclera. Thus, the ocular space was illuminated transsclerally. As a result, indirect uniform illumination of the complete intraocular space was achieved. The prototype was developed considering the relevant international standards. Porcine eyes were used because their properties are similar to those of human eyes. RESULTS Porcine eyes could be acceptably illuminated with the selected LED. The LED-endoilluminator conforms with international standards for endoillumination. Thus, possible photochemical and thermal risks are considered and reduced to a minimum. CONCLUSIONS A novel LED-endoilluminator which can be attached to a speculum was developed. The system does not need any connection to an external light source and, consequently, also avoids usage of an optical fibre. Regular and uniform illumination of the intraocular space was achieved by transmitted and scattered visible irradiation, avoiding an incision. The duration of potential light exposure, compared to existing illumination systems, can be significantly increased. This is also true when the illuminator is not directly placed over the pars-plana and the distance to the retina is reduced. Only a part of the light reaches the retina and the fraction of short wavelength becomes very small. Increased safety of the system results from now being able to increase the exposure time and reduce phototoxic stress to the retina.
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Affiliation(s)
- Philipp Simon Kölbl
- Department of Mechatronics and Medical Engineering, Ulm University of Applied Sciences, Albert-Einstein-Allee 55, D-89081, Ulm, Germany
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Abstract
Proliferative vitreoretinopathy in the inferior retina remains clinically challenging. Heavier-than-water intraocular tamponades have been developed to improve inferior tamponading properties. The parameters of an optimal intraocular tamponade are defined and the influences of the specific gravity, buoyancy, interfacial tension, and viscosity are discussed. Perfluorocarbon liquids and partially fluorinated alkanes were associated with tamponade emulsification, intraocular inflammation, and rises in intraocular pressure that were less prominent in admixtures of these substances with silicone oil (heavy silicone oils). Two recently developed heavy silicone oil tamponades, Oxane HD and Densiron 68, are well tolerated and have entered clinical practice. The side effects are associated with the chemical properties of the tamponading agent and seem comparable to those seen with conventional silicone oil. Heavy silicone oil tamponade improves inferior tamponade and may be considered as a new generation of intraocular tamponades.
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Schroeder AC, Lingenfelder C, Seitz B, Grabowy U, W Spraul C, Gatzioufas Z, Herrmann M. Impact of fibronectin on surface properties of intraocular lenses. Graefes Arch Clin Exp Ophthalmol 2009; 247:1277-83. [PMID: 19578868 DOI: 10.1007/s00417-009-1130-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 06/15/2009] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Physical properties of intraocular lens (IOL) surfaces determine biocompatibility. IOL hydrophobicity of commercially available IOLs with and without fibronectin (FN) coating can be determined by surface contact angle (SCA) measurements. SCA data of IOLs may allow for a rational selection of an IOL type as a function of underlying eye disease. SETTING University Hospital of Saarland, Homburg (Saar), Germany METHODS Thirteen IOL types were tested. IOLs were made of poly(methyl methacrylate)(PMMA), acrylate, or silicone. Select IOLs were surface modified by the manufacturer with heparin or a polysaccharide coating. SCA values of IOLs, either uncoated or precoated with FN, were determined using the sessile water drop method. RESULTS SCA values ranged from 61.3 to 116.1 degrees for unmodified IOLs, with PMMA IOLs being more hydrophilic (median SCA, 74.1 degrees ), silicone IOLs more hydrophobic (median SCA, 113.3 degrees ), and acrylate IOLs intermediate (median SCA, 86.6 degrees ). Upon FN coating, all genuine acrylate lenses became significantly more hydrophilic while this effect was either nonsignificant or opposite on some PMMA and silicon IOLs. Heparin or polysaccharide surface modification resulted in significantly reduced SCA values. On acrylate IOLs, SCA values did not correlate with the aqueous content of the material. CONCLUSIONS This study associates IOL materials, surface modifications, and the role of FN preadsorption with SCA values reflecting surface hydrophobicity versus hydrophilicity. It provides a rationale for specific IOL selection as a function of the clinical setting, and a basis for IOL development using tailored surface physicochemistry to enhance biocompatibility and to reduce susceptibility to implant infection.
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Affiliation(s)
- Andreas C Schroeder
- Department of Ophthalmology, University of Saarland Hospital, 66421 Homburg, Saar, Germany.
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Schröder AC, Lingenfelder C, Seitz B. Einfluss einer Kohlenstoff-Beschichtung auf die Eigenschaften einer IOL. Klin Monbl Augenheilkd 2009. [DOI: 10.1055/s-0029-1213723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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21
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Schröder AC, Lingenfelder C, Seitz B. Vergleich der Färbung und Entfärbung 3 verschiedener Farbstoffe bei Kunstlinsen verschiedener Materialien. Klin Monbl Augenheilkd 2008. [DOI: 10.1055/s-2008-1057955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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22
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Schröder AC, Bohle RM, Lingenfelder C, Seitz B. Vergleich der Wasseraufnahme und -abgabe verschiedener Acrylat-Kunstlinsen. Klin Monbl Augenheilkd 2007. [DOI: 10.1055/s-2007-976238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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23
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Spraul CW, Rawer R, Stork W, Walther P, Lingenfelder C, Lang GK. [Does the orientation of the IOL in the eye play a role? Imaging quality of foldable intraocular lenses measured utilizing point spread function (PSF-measurement) and scanning electron microscopy cross-sectional images]. Klin Monbl Augenheilkd 2005; 222:972-6. [PMID: 16380883 DOI: 10.1055/s-2005-858691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND Foldable intraocular lenses (IOLs) are established in ophthalmic surgery and increasingly more complex geometries are available. This study investigates different designs of the optics of the IOL as well as the imaging quality of these optics utilizing electron microscopic photographs and mathematical approximations. METHOD Included in this study were two different lens powers of common IOLs (+ 13 D and + 26 D). All studied IOLs were processed depending upon their water content: Aqueous IOLs with up to 25 % water content were fixed with 2.5 % glutaraldehyde in 0.1 M phosphate buffer (mPP), and then contrasted with 2 % OsO (4) and processed in an alcohol series of 30 - 100 % propanol. Subsequently, the IOLs were transferred into EPON (epoxy resin) and polymerization took place at 60 degrees C. After hardening, the samples were cut out with a leaves saw and divided into halves. Afterwards these were polished with glass and diamond knifes at the ultramicrotom (Ultracut, Rückert-Jung). After coal vaporization measurement took place in the scanning electron microscope (DSM 962, Zeiss). In the case of dry stored IOLs, the samples were sputtered with Au-Pd 20 nm and afterwards measurement was performed as described above. The measurement of the optical imaging quality was performed with correctly and inversely oriented IOLs according to the standard EN ISO 11979 -- 2 by means of a measuring system which works on the basis of the point spread function (PSF) and/or the modulation transfer function (MTF). From this the Strehl ratio was computed in each case. RESULTS Utilizing a correlation of the electron microscopic investigation of the optics of different IOLs with their imaging quality (Strehl ratio), we were able to show that the optical design of the IOL has substantial influence on the imaging quality of an intraocular lens. In particular, with non-symmetrical designs of the optics (e. g., AR40 e; AMO) the orientation of an IOL in the eye is crucial; i. e., the Strehl ratio increased thereby from 0.68 to 0.87. CONCLUSIONS The design of asymmetrical optics is crucial and much attention should be paid to the fact that the imaging quality can substantially be affected. A correct orientation of the lens within the eye is very important with these asymmetrical optics.
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Abstract
PURPOSE Today, for the preparation of donor and recipient cornea during keratoplasty either single-use or reusable metal trephines are commonly used although excimer and femtosecond laser systems are available. Due to the surgical techniques as well as the configuration of metal trephine's cutting edge irregular corneal surfaces may be induced. These will result in a postoperative astigmatism. Contemporary manufacturing processes do allow for the production of minimal cutting edge diameters (400 nm -- 1 microm), however, this is related with a reduced mechanical stability of such delicate cutting edges. It has been observed that the cutting edge of metal blades is immediately bent with the first exposure to tissue. As a result, the cutting forces are increasing and the wound configuration is negatively effected. Due to the complex geometry of trephine cutting edges, no diamond trephines are currently available. We are investigating the cutting performance of conventional trephines that were modified using nanotechnology. METHOD Different metal trephines were characterised using a scanning electron microscope (SEM). The diameter of the cutting edge was measured. Pig cornea were studied histologically after trepanation. Selected trephines were ion-forged in a modified PVD (physical vapour deposition) reactor using highly accelerated ions which are concentrated by magnetic fields at low temperature. The consecutive processing steps were controlled by SEM analysis of the cutting edge diameters. Randomly chosen areas of treated trephines were analysed. After processing the trephines, pig cornea were cut and analysed by histological and SEM examination. Additionally, the relevant mechanical cutting parameters of untreated as well as treated trephines were measured when penetrating into a PU (polyurethane) foil. RESULTS Preliminary microscopic analysis already reveals differences in the quality of the cutting edges. The nanotechnological modification of the cutting edges does not result in larger diameters. Compared with the initial cutting edges, the optical analysis of the modified trephine cutting edges reveals subjectively smoother surfaces. The force measurements prove a reduction of cutting forces for the treated trephines compared to the untreated ones. The SEM analysis show for the cornea treated with the modified trephines a subjectively smoother surface. Histology reveals that the surfaces of the treated cornea do not exhibit a smooth and unidirectional structure. This divergence became larger when untreated trephines were used. The mechanical characterisation of the treated trephines resulted in harder and longer-lasting surfaces. DISCUSSION The newly developed ion-forging of trephines in combination with nanostructured carbon coatings yield complex cutting edges of higher stability with diamond-like properties. This study shows that the performance of laser trepanation cannot be reached; however, the use of nanotechnology can further improve manual trephine techniques.
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Abstract
PURPOSE To compare the imaging quality of several commercially available intraocular lenses (IOLs) using the modulation transfer function (MTF) method according to the requirements of the International Standard European Industrial Norm/International Organization for Standardization 11979. SETTING Universitat für Technik der Informationsverarbeitung, Universität Karlsruhe, Karlsruhe and Universitäts Augenklinik, Ulm, Ulm, Germany. METHODS Two refractive powers (+13 diopter [D] and +26 D) of each IOL type were tested. The imaging quality of all tested IOLs was measured before the injection test and in 5-minute intervals after the injection for 40 minutes. The measurement data were analyzed according to 2 quality criteria, Strehl ratio and the ISO condition. For analysis of the type of optical design, SEM images of the central cross section were taken of each IOL. Basic terms in optics such as MTF, resolution, and optical aberration are introduced, and their relevance for ophthalmology is discussed in detail. This paper represents an extensive study comparing the imaging quality of various IOLs including the comparison of measurements before and after injection through a cartridge as used for state-of-the-art implantation techniques. All measurements were performed using an MTF measurement system using a 546 nm optimized laser source and an effective aperture of 3.0 mm on the IOL according to ISO standard. An ISO standard eye model using an artificial cornea (spherical design) and a watery solution to simulate in vivo conditions was used. RESULTS All IOLs apart from 1 +26 D lens complied with ISO standard requirements. However, the imaging quality varied up to 49% depending on the optical design and the manufacturing quality. CONCLUSION When the methods and materials recommended by the manufacturer for IOL injection through a cartridge were used, no long-term effect on the imaging quality of the IOLs was observed. However, the basic imaging quality of different designs and different manufacturers varied significantly (up to 50% at +26 D) IOLs and should be considered when choosing an IOL.
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Affiliation(s)
- Rainer Rawer
- Institut für Technik der Informationsverarbeitung, Universität Karlsruhe, Karlsruhe, Berlin, Germany.
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Schröder AC, Lingenfelder C, Ruprecht KW. Einfluss von Fibronektin auf die Hydrophobizität verschiedener Intraokularlinsen. Klin Monbl Augenheilkd 2004. [DOI: 10.1055/s-2004-835471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Spraul CW, Ertl S, Strobel S, Gretzschel R, Schirmer E, Rösch R, Lingenfelder C, Lang GK. [Manufacture of diamond blades via microsystem technology]. Klin Monbl Augenheilkd 2003; 220:229-34. [PMID: 12695964 DOI: 10.1055/s-2003-38624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
PURPOSE The application of diamond knives has steadily increased in ophthalmic surgery. However, the geometry of the blade, its thickness and the sharpness of the cutting edge are limited by the abrasive diamond polishing process, e. g. the crystalline morphology of the bulk material and the grinding powder used. A new generation of diamond blades is presented herewith allowing free choice of blade shape and thickness and possessing excellent sharpness due to a new polishing process. METHODS The new production method is based on a high-quality CVD (chemical vapour deposition) diamond film of some tenths of microns thickness, deposited on a silicon wafer as microchip technology. The mechanical properties of this synthetic diamond film are almost equal to those of a natural diamond and the surface of this film is mirror-like after deposition without requiring post-polishing. The shape of the blade can be freely defined and is transferred into the diamond film by a plasma polishing process adopted from microsystem technology. RESULTS The new production method results in highly reproducible diamond blades. Concave blades and round shapes can now be realised without the restrictions of the conventional production process. The force-free fabrication method even allows realisation of miniaturized blades (e. g. width < 0.125 mm, thickness < 50 microm) far beyond the possibilities of conventional diamond blade production. Plasma polishing by means of gas atoms results in extreme sharpness with the cutting edge radius in the range of approx. 3 nm. CONCLUSIONS Utilising microsystem technology we were able to manufacture reproducible artificial diamond blades. The new process offers for the first time surgeons a possibility of designing blades with a geometry close to their personal needs. Furthermore, the potential of facet-free ergonomically shaped diamond blades may stimulate further improvements towards novel surgical techniques.
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