The Experts below are selected from a list of 537 Experts worldwide ranked by ideXlab platform
Alice Z Chuang - One of the best experts on this subject based on the ideXlab platform.
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prediction of corneal haze using an ablation depth corneal thickness ratio after Laser Epithelial Keratomileusis
Journal of Refractive Surgery, 2004Co-Authors: Shrabanee Mitra, Alice Z ChuangAbstract:PURPOSE: To investigate the usefulness of ablation depth/corneal thickness (AD/CT) ratio to predict corneal haze after Laser Epithelial Keratomileusis (LASEK) using a retrospective, comparative, interventional case series. METHODS: Fifty patients (90 eyes; mean age 40.9 years) with myopia, hyperopia, and/or astigmatism underwent bilateral or unilateral LASEK for correction of refractive error. After Epithelial flaps were created using an 18% alcohol solution, bilateral or unilateral LASEK was performed using the Alcon Autonomous LADARVision 4000 excimer Laser. Visual acuity (best spectacle-corrected and uncorrected) and refractive error were measured before and after LASEK. Corneas were assessed by two independent evaluators under a slit-lamp biomicroscope with broad tangential illumination. The relative haze scale was quantitated: 0 (clear), 0.5+ (trace), 1+ (mild), 2+ (moderate), 3+ (marked), and 4+ (severe). RESULTS: Mean preoperative spherical equivalent refraction was -5.46 +/- 3.74 D (range -12.375 to +5.00 D), mean ablation depth was 93.04 +/- 45.03 microm (range 21.2 to 207.2 microm), and mean AD/CT ratio was 0.18 +/- 0.09 (range 0.04 to 0.41). Of 90 eyes, 40 eyes had a higher ablation depth (AD/CT ratio > 0.18) and 50 eyes had a lower ablation depth (AD/CT ratio < 0.18); 92.5% of eyes in the higher ratio group developed clinically significant haze (1+ or greater). In the lower ratio group, 94% of eyes developed no more than 1+ corneal haze, if any. CONCLUSION: The ablation depth/corneal thickness ratio is useful for predicting corneal haze after LASEK. An AD/CT ratio of 0.18 or more suggests that patients have a high risk of developing clinically significant haze (1+ or more) after LASEK.
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Prediction of corneal haze using an ablation depth/corneal thickness ratio after Laser Epithelial Keratomileusis
Journal of Refractive Surgery, 2004Co-Authors: Shrabanee Mitra, Alice Z ChuangAbstract:PURPOSE: To investigate the usefulness of ablation depth/corneal thickness (AD/CT) ratio to predict corneal haze after Laser Epithelial Keratomileusis (LASEK) using a retrospective, comparative, interventional case series. METHODS: Fifty patients (90 eyes; mean age 40.9 years) with myopia, hyperopia, and/or astigmatism underwent bilateral or unilateral LASEK for correction of refractive error. After Epithelial flaps were created using an 18% alcohol solution, bilateral or unilateral LASEK was performed using the Alcon Autonomous LADARVision 4000 excimer Laser. usual acuity (best spectacle-corrected and uncorrected) and refractive error were measured before and after LASEK. Corneas were assessed by two independent evaluators under a slit-lamp biomicroscope with broad tangential illumination. The relative haze scale was quantitated: 0 (clear), 0.5+ (trace), 1+ (mild), 2+ (moderate), 3+ (marked), and 4+ (severe). RESULTS: Mean preoperative spherical equivalent refraction was -5.46 ± 3.74 D (range -12.375 to +5.00 D), mean ablation depth was 93.04 ± 45.03 μm (range 21.2 to 207.2 μm), and mean AD/CT ratio was 0.18 ± 0.09 (range 0.04 to 0.41). Of 90 eyes, 40 eyes had a higher ablation depth (AD/CT ratio >0.18) and 50 eyes had a lower ablation depth (AD/CT ratio
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Laser Epithelial Keratomileusis for myopia with the autonomous Laser
Journal of Refractive Surgery, 2002Co-Authors: Rajy M Rouweyha, Alice Z Chuang, Shrabanee Mitra, Chris PhillipsAbstract:PURPOSE: To describe the refractive outcome, objective clinical data, and subjective patient experiences after Laser Epithelial Keratomileusis (LASEK) at 1, 3, and 6 months after surgery. METHODS: This was a retrospective, nonrandomized, comparative study of 58 LASEK-treated eyes (36 patients) with myopia (with and without astigmatism) between -1.50 and -14.75 D (mean -7.80 +/- 2.90 D, median -7.90 D). Refractive surgery was performed using the Alcon Summit Autonomous LADAR Vision excimer Laser. Manifest refraction, best-spectacle and uncorrected Snellen visual acuity, stability of refraction, and corneal haze were evaluated before surgery and up to 6 months after surgery. A group of randomly selected LASIK-treated eyes were compared at each time point. RESULTS: Patients who opted for monovision (n=12) were excluded. In the emmetropia targeted eyes (n=46), 45%, 83%, 85%, and 89% achieved 20/40 or better uncorrected Snellen visual acuity (UCVA) at 1 day, 1 week, 2 weeks, and 1 month respectively. At 6 months, 73% (n=28) of eyes treated achieved UCVA 20/20 with 97% achieving 20/40 or better (mean, -0.51 D). At 3 and 6 months, 71% (n=46) and 68% (n=28) were within +/- 0.50 D of emmetropia. The percentage of eyes that achieved UCVA 20/40 or better at 6 months was 97% (n=28). Visually significant corneal haze was evident in two LASEK-treated patients (four eyes) at 6 months. No eyes lost two or more lines of best spectacle-corrected Snellen visual acuity. CONCLUSIONS: Preliminary data suggest that LASEK appears to be a safe, effective, and comparable alternative to LASIK, even for higher amounts of myopia. A prospective, randomized clinical trial is needed to better define the role of LASEK as it compares to other refractive procedures, specifically LASIK and PRK.
Michael Okeefe - One of the best experts on this subject based on the ideXlab platform.
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one year follow up of contrast sensitivity following conventional Laser in situ Keratomileusis and Laser Epithelial Keratomileusis
Acta Ophthalmologica, 2012Co-Authors: Deirdre Townley, Caitriona Kirwan, Michael OkeefeAbstract:. Purpose: To determine the effect of conventional Laser in situ Keratomileusis (LASIK) and Laser Epithelial Keratomileusis (LASEK) for myopia on contrast sensitivity (CS) using the Pelli-Robson and Vector Vision CSV-1000E CS tests. Methods: A prospective, comparative study was conducted on 36 eyes of 36 patients with myopia undergoing LASIK (18 eyes) and LASEK (18 eyes). Surgery was performed using the Technolas 217z Laser (Bausch & Lomb). CS was recorded preoperatively and at 3, 6 and 12 months postoperatively. Results: No statistically significant difference was found in LogMAR uncorrected visual acuity post-LASIK (−0.02 ± 0.16) and LASEK (−0.04 ± 0.14). Using the Pelli-Robson, CS was significantly lower in the LASIK group 3 and 6 months postoperatively. No significant postoperative reduction in CS was observed in either treatment group. Using the CSV-1000E test, CS was significantly reduced post-LASIK at 3 (p = 0.05) and 6 (p = 0.05) cycles/degree under photopic conditions. No significant postoperative change occurred in the LASEK group under photopic or scotopic conditions. There was no significant difference in postoperative CS between the LASIK and LASEK groups at 3, 6, 12 or 18 cycles/degree using the CSV-1000E test. Conclusion: One year postoperatively, there was no difference in CS between both treatment groups using the Pelli-Robson and CSV-1000E tests. CS was reduced postoperatively in the LASIK group at the lower spatial frequencies under photopic conditions. No postoperative change was detected in CS following LASIK or LASEK using the Pelli-Robson test.
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Laser Epithelial Keratomileusis in 2010 a review
Clinical and Experimental Ophthalmology, 2010Co-Authors: Michael Okeefe, Caitriona KirwanAbstract:: Photorefractive keratectomy, Laser Epithelial Keratomileusis (LASEK) and Epi-LASIK are all variants of a similar type refractive surgery involving Laser on the surface of the cornea and differ mainly in management of the epithelium. Although Laser in situ Keratomileusis (LASIK) is currently the most popular form of refractive surgery, LASEK is the procedure of choice in some patients. We highlight potential complications of LASEK and how these may be managed. Following Laser refractive surgery, corneal thickness is reduced, which has implications for intraocular pressure measurement and glaucoma screening and management. This is particularly important following surface Laser procedures where no evidence of previous surgery may be visible. In the event that cataract surgery is required at a later date, correct calculation of the appropriate intraocular lens power can be difficult and it thus important that patients are given their preoperative keratometry readings and refraction. Compared with LASIK patients, those who undergo LASEK are considered to be at lower risk of corneal ectasia. Improved understanding of wound healing post LASEK and better postoperative pain management are ongoing challenges.
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comparative study of higher order aberrations after conventional Laser in situ Keratomileusis and Laser Epithelial Keratomileusis for myopia using the technolas 217z Laser platform
American Journal of Ophthalmology, 2009Co-Authors: Caitriona Kirwan, Michael OkeefeAbstract:Purpose To examine changes in higher-order aberrations (HOAs) after PlanoScan Laser in situ Keratomileusis and (LASIK) and Laser Epithelial Keratomileusis (LASEK). Design Prospective, comparative study. Methods Myopic patients undergoing LASIK (65 eyes of 36 patients) and LASEK (50 eyes of 28 patients) at a private practice were selected randomly. Surgery was performed using the Technolas 217z Laser (Bausch & Lomb, Surrey, United Kingdom). Main outcome measures included uncorrected visual acuity (UCVA), manifest refractive spherical equivalent (MRSE), and aberrometry (Zywave; Bausch & Lomb, Rochester, New York, USA) and were recorded before surgery and at three and 12 months after surgery. Results There was no statistical difference between both groups in terms of MRSE ( P = .91), ablation depth ( P = .47), scotopic pupil size ( P = .38), or optical zone ( P = .07). Before surgery, there was no statistical difference in root mean square (RMS) of total ( P = .70), third- ( P = .79), fourth- ( P = .23), and fifth- ( P = .33) order aberrations and individual terms. Three months after surgery, RMS of total HOA was raised significantly more ( P = .03) after LASIK (1.46-factor increase) than LASEK (1.25-factor increase). One year after surgery, a reduction in total HOAs was observed in 13.8% of LASIK- and 48.5% of LASEK-treated eyes compared with preoperative levels. Conclusions Postoperative increases in total HOA and vertical coma were significantly greater in LASIK- than in LASEK-treated eyes. Postoperative reduction in total HOAs was observed in a number of eyes with high preoperative levels and occurred more frequently in LASEK-treated eyes.
Shrabanee Mitra - One of the best experts on this subject based on the ideXlab platform.
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prediction of corneal haze using an ablation depth corneal thickness ratio after Laser Epithelial Keratomileusis
Journal of Refractive Surgery, 2004Co-Authors: Shrabanee Mitra, Alice Z ChuangAbstract:PURPOSE: To investigate the usefulness of ablation depth/corneal thickness (AD/CT) ratio to predict corneal haze after Laser Epithelial Keratomileusis (LASEK) using a retrospective, comparative, interventional case series. METHODS: Fifty patients (90 eyes; mean age 40.9 years) with myopia, hyperopia, and/or astigmatism underwent bilateral or unilateral LASEK for correction of refractive error. After Epithelial flaps were created using an 18% alcohol solution, bilateral or unilateral LASEK was performed using the Alcon Autonomous LADARVision 4000 excimer Laser. Visual acuity (best spectacle-corrected and uncorrected) and refractive error were measured before and after LASEK. Corneas were assessed by two independent evaluators under a slit-lamp biomicroscope with broad tangential illumination. The relative haze scale was quantitated: 0 (clear), 0.5+ (trace), 1+ (mild), 2+ (moderate), 3+ (marked), and 4+ (severe). RESULTS: Mean preoperative spherical equivalent refraction was -5.46 +/- 3.74 D (range -12.375 to +5.00 D), mean ablation depth was 93.04 +/- 45.03 microm (range 21.2 to 207.2 microm), and mean AD/CT ratio was 0.18 +/- 0.09 (range 0.04 to 0.41). Of 90 eyes, 40 eyes had a higher ablation depth (AD/CT ratio > 0.18) and 50 eyes had a lower ablation depth (AD/CT ratio < 0.18); 92.5% of eyes in the higher ratio group developed clinically significant haze (1+ or greater). In the lower ratio group, 94% of eyes developed no more than 1+ corneal haze, if any. CONCLUSION: The ablation depth/corneal thickness ratio is useful for predicting corneal haze after LASEK. An AD/CT ratio of 0.18 or more suggests that patients have a high risk of developing clinically significant haze (1+ or more) after LASEK.
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Prediction of corneal haze using an ablation depth/corneal thickness ratio after Laser Epithelial Keratomileusis
Journal of Refractive Surgery, 2004Co-Authors: Shrabanee Mitra, Alice Z ChuangAbstract:PURPOSE: To investigate the usefulness of ablation depth/corneal thickness (AD/CT) ratio to predict corneal haze after Laser Epithelial Keratomileusis (LASEK) using a retrospective, comparative, interventional case series. METHODS: Fifty patients (90 eyes; mean age 40.9 years) with myopia, hyperopia, and/or astigmatism underwent bilateral or unilateral LASEK for correction of refractive error. After Epithelial flaps were created using an 18% alcohol solution, bilateral or unilateral LASEK was performed using the Alcon Autonomous LADARVision 4000 excimer Laser. usual acuity (best spectacle-corrected and uncorrected) and refractive error were measured before and after LASEK. Corneas were assessed by two independent evaluators under a slit-lamp biomicroscope with broad tangential illumination. The relative haze scale was quantitated: 0 (clear), 0.5+ (trace), 1+ (mild), 2+ (moderate), 3+ (marked), and 4+ (severe). RESULTS: Mean preoperative spherical equivalent refraction was -5.46 ± 3.74 D (range -12.375 to +5.00 D), mean ablation depth was 93.04 ± 45.03 μm (range 21.2 to 207.2 μm), and mean AD/CT ratio was 0.18 ± 0.09 (range 0.04 to 0.41). Of 90 eyes, 40 eyes had a higher ablation depth (AD/CT ratio >0.18) and 50 eyes had a lower ablation depth (AD/CT ratio
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Laser Epithelial Keratomileusis for myopia with the autonomous Laser
Journal of Refractive Surgery, 2002Co-Authors: Rajy M Rouweyha, Alice Z Chuang, Shrabanee Mitra, Chris PhillipsAbstract:PURPOSE: To describe the refractive outcome, objective clinical data, and subjective patient experiences after Laser Epithelial Keratomileusis (LASEK) at 1, 3, and 6 months after surgery. METHODS: This was a retrospective, nonrandomized, comparative study of 58 LASEK-treated eyes (36 patients) with myopia (with and without astigmatism) between -1.50 and -14.75 D (mean -7.80 +/- 2.90 D, median -7.90 D). Refractive surgery was performed using the Alcon Summit Autonomous LADAR Vision excimer Laser. Manifest refraction, best-spectacle and uncorrected Snellen visual acuity, stability of refraction, and corneal haze were evaluated before surgery and up to 6 months after surgery. A group of randomly selected LASIK-treated eyes were compared at each time point. RESULTS: Patients who opted for monovision (n=12) were excluded. In the emmetropia targeted eyes (n=46), 45%, 83%, 85%, and 89% achieved 20/40 or better uncorrected Snellen visual acuity (UCVA) at 1 day, 1 week, 2 weeks, and 1 month respectively. At 6 months, 73% (n=28) of eyes treated achieved UCVA 20/20 with 97% achieving 20/40 or better (mean, -0.51 D). At 3 and 6 months, 71% (n=46) and 68% (n=28) were within +/- 0.50 D of emmetropia. The percentage of eyes that achieved UCVA 20/40 or better at 6 months was 97% (n=28). Visually significant corneal haze was evident in two LASEK-treated patients (four eyes) at 6 months. No eyes lost two or more lines of best spectacle-corrected Snellen visual acuity. CONCLUSIONS: Preliminary data suggest that LASEK appears to be a safe, effective, and comparable alternative to LASIK, even for higher amounts of myopia. A prospective, randomized clinical trial is needed to better define the role of LASEK as it compares to other refractive procedures, specifically LASIK and PRK.
John C Marshall - One of the best experts on this subject based on the ideXlab platform.
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Laser Epithelial Keratomileusis for the correction of hyperopia using a 7 0 mm optical zone with the schwind esiris Laser
Journal of Refractive Surgery, 2007Co-Authors: David P S Obrart, Faye Mellington, Sophie Jones, John C MarshallAbstract:PURPOSE: To investigate the efficacy of Laser Epithelial Keratomileusis (LASEK) for the correction of hyperopia using a 7.0-mm optical zone and a 9.0-mm total ablation zone diameter with the Schwind ESIRIS flying-spot Laser. METHODS: Forty-seven patients (70 eyes) were treated with a mean preoperative spherical equivalent refraction of +2.32 diopters (D) (range: 0 to +5.00 D). All eyes underwent LASEK using 15% alcohol with a 20-second application. RESULTS: An intact Epithelial flap was obtained in 66 (94%) eyes. In 70 eyes at 12 months, the mean spherical equivalent refraction was +0.09 D (range: -0.75 to +1.00 D) with all (100%) eyes within +/- 1.00 D of the intended correction and 60 (86%) eyes within +/- 0.50 D. In 40 eyes with 24-month follow-up, the refractive correction remained stable after 6 months. Hyperopic cylindrical corrections were attempted in 49 eyes (range: +0.25 to +5.00 D) with vector analysis demonstrating a mean 102% correction at 12 to 24 months. In 60 non-amblyopic eyes, uncorrected visual acuity was > or = 20/20 in 47 (78%) eyes. Thirty-three (47%) eyes gained 1 to 2 lines of Snellen decimal equivalent best spectacle-corrected visual acuity, 30 (43%) eyes showed no change, and 7 (10%) eyes lost 1 line. Eight (11%) eyes at 12 to 24 months had grade +/- 1 of paracentral corneal haze and 57 (81%) had no haze. At 12 months (n = 70), the safety index was 1.06 with an efficacy index of 0.95. Analysis of higher order wavefront aberrations showed no significant changes in root-mean-square values post-operatively, except for a significant reduction of fourth order spherical aberration (P < .05). CONCLUSIONS: Laser Epithelial Keratomileusis for hyperopia up to +5.00 D using a 7.0-mm optical zone with the Schwind ESIRIS Laser provides excellent refractive and visual outcomes with minimal complications. In eyes followed for 24 months, the refractive correction remained stable after 6 months.
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Laser Epithelial Keratomileusis lasek histological investigation for vitality of corneal Epithelial cells after alcohol exposure
Klinische Monatsblatter Fur Augenheilkunde, 2002Co-Authors: Alexandra K Dreiss, Christoph Winkler Von Mohrenfels, B Gabler, John C Marshall, Thomas Kohnen, Chris P LohmannAbstract:BACKGROUND: Laser Epithelial Keratomileusis (LASEK) is a new surgical procedure to treat myopia. An Epithelial flap is created after the exposure to 20 % alcohol and following the Laser ablation the epithelium is repositioned to its original location. The advantage of LASEK is that the ablated corneal surface is covered by a full thickness epithelium immediately after surgery. It is hypothesised that this Epithelial coverage inhibits the wound healing response of the cornea. However, this concept will only work if the Epithelial cells are still vital after the exposure to alcohol. MATERIAL AND METHODS: The vitality of the corneal Epithelial cells was investigated in 6 human cadaver eyes after the exposure to 20 % alcohol over 15 to 60 s. The vitality of the corneal Epithelial cells was assessed by soaking the specimen in a 0.1 % trypan blue solution and incubated at 37 degrees C for 2 min. After a wash with BSS the specimen were re-incubated at 37 degrees C for 30 min in culture medium. After one more wash with BSS the cells were observed with a standard light microscope. Cells which retained the blue colour would be dead and vital cells would appear clear. Light microscopy and transmission electron microscopy was used to detect morphological changes. RESULTS: Mainly vital corneal Epithelial cells were seen for an alcohol exposure time of up to 30 s. In particular the basal Epithelial cells appeared alive. With a exposition time of 60 s most cells were dead. CONCLUSION: In LASEK the exposure time of 20 % alcohol is between 20 and 30 s. Based on our results we can conclude that after such exposure time most cells are alive, which is essential for the postoperative wound healing response.
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Laser Epithelial Keratomileusis (LASEK): histological investigation for vitality of corneal Epithelial cells after alcohol exposure
Klinische Monatsblatter Fur Augenheilkunde, 2002Co-Authors: Alexandra K Dreiss, Christoph Winkler Von Mohrenfels, B Gabler, John C Marshall, Thomas Kohnen, Chris P LohmannAbstract:Background: Laser Epithelial Keratomileusis (LASEK) is a new surgical procedure to treat myopia. An Epithelial flap is created after the exposure to 20% alcohol and following the Laser ablation the epithelium is repositioned to its original location. The advantage of LASEK is that the ablated corneal surface is covered by a full thickness epithelium immediately after surgery. It is hypothesised that this Epithelial coverage inhibits the wound healing response of the cornea. However, this concept will only work if the Epithelial cells are still vital after the exposure to alcohol. Material and methods: The vitality of the corneal Epithelial cells was investigated in 6 human cadaver eyes after the exposure to 20% alcohol over 15 to 60s. The vitality of the corneal Epithelial cells was assessed by soaking the specimen in a 0.1% trypan blue solution and incubated at 37°C for 2 min. After a wash with BSS the specimen were re-incubated at 37°C for 30 min in culture medium. After one more wash with BSS the cells were observed with a standard light microscope. Cells which retained the blue colour would be dead and vital cells would appear clear. Light microscopy and transmission electron microscopy was used to detect morphological changes. Results: Mainly vital corneal Epithelial cells were seen for an alcohol exposure time of up to 30 s. In particular the basal Epithelial cells appeared alive. With a exposition time of 60 s most cells were dead. Conclusion: In LASEK the exposure time of 20% alcohol is between 20 and 30 s. Based on our results we can conclude that after such exposure time most cells are alive, which is essential for the postoperative wound healing response.
Christoph Winkler Von Mohrenfels - One of the best experts on this subject based on the ideXlab platform.
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Live or Let Die: Epithelial Flap Vitality and Keratocyte Proliferation Following LASEK and Epi-LASIK in Human Donor and Porcine Eyes.
Journal of Refractive Surgery, 2010Co-Authors: Romesh I. Angunawela, Christoph Winkler Von Mohrenfels, A. Kumar, David P.s. O'brart, John MarshallAbstract:To determine the relationship between Epithelial flap vitality and stromal keratocyte proliferation following two Epithelial refractive techniques: epi-LASIK and Laser Epithelial Keratomileusis (LASEK).Human corneas were maintained in organ culture and underwent standard -6.00-diopter ablation. Rates of stromal keratocyte proliferation were detected 1 week postoperative using a Ki67 antibody specific to proliferating cells. Images were captured with a Laser scanning confocal microscope and analyzed by a masked observer. Epithelial flap vitality was determined with propidium iodide using fresh porcine corneas. Epithelial flaps were created with Gebauer Epikeratome epi-LASIK or alcohol-assisted LASEK method. Flaps treated with 100% alcohol and uninjured corneas were used as controls.The number of proliferating keratocytes was greatest at 1 week in the epi-LASIK corneas (P
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corneal sensation after Laser Epithelial Keratomileusis for the correction of myopia
Graefes Archive for Clinical and Experimental Ophthalmology, 2005Co-Authors: W Herrmann, Chirag Shah, B Gabler, Christoph Winkler Von Mohrenfels, K Hufendiek, Chris P LohmannAbstract:Background SubEpithelial nerve fibre bundles and stromal nerves are damaged during Laser Epithelial Keratomileusis (LASEK). The aim of this study was to investigate the recovery of corneal sensation after LASEK for the correction of myopia.
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wavefront guided Laser Epithelial Keratomileusis with the wavelight concept system 500
Journal of Refractive Surgery, 2004Co-Authors: Christoph Winkler Von Mohrenfels, B Gabler, Andrea Huber, Wolfgang A Herrmann, Alexander Kempe, Christof Donitzky, Chris P LohmannAbstract:PURPOSE: Laser Epithelial Keratomileusis (LASEK) is a technique of refractive surgery for treatment of myopia. More than 90% of patients are within the intended correction of +/-0.50 diopters (D), without any unwanted side effects. After conventional refractive surgery, higher-order aberrations are induced. To reduce these aberrations, we used wavefront-guided ablation. METHODS: Twenty patients with visual problems in ambient light were included. The primary surgery was 141 to 463 days before the retreatment. LASEK was performed with the Camellin technique with 20% EtOH for 30 seconds. Before surgery, the root mean square (RMS) values were measured and the Laser treatment was performed with the WaveLight Concept System 500 (WaveLight Laser Technologie AG). The preoperative spherical equivalent refraction was -1.22 D (SD 0.57 D) and the astigmatism was -0.42 D (SD 0.25 D). Preoperatively and 6 months postoperatively, a comprehensive examination was performed. RESULTS: All retreatments were performed without any intra- or postoperative complications. All patients reported an improvement of vision. The 6-month postoperative refraction was 0.25 D (SD 0.36 D). RMS decreased significantly from 0.72 to 0.47. RMS fourth order also decreased significantly from 0.60 to 0.30 and the spherical aberration decreased significantly from 0.57 to 0.28. CONCLUSIONS: In earlier studies, patients reported reduction of contrast vision, even after resurgery. Our patients showed a significant reduction of higher-order aberrations and better contrast vision after retreatment with wavefront guided LASEK. Retreatment with wavefront-guided LASEK has the potential to correct night vision problems after excimer Laser surgery.
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Laser Epithelial Keratomileusis lasek histological investigation for vitality of corneal Epithelial cells after alcohol exposure
Klinische Monatsblatter Fur Augenheilkunde, 2002Co-Authors: Alexandra K Dreiss, Christoph Winkler Von Mohrenfels, B Gabler, John C Marshall, Thomas Kohnen, Chris P LohmannAbstract:BACKGROUND: Laser Epithelial Keratomileusis (LASEK) is a new surgical procedure to treat myopia. An Epithelial flap is created after the exposure to 20 % alcohol and following the Laser ablation the epithelium is repositioned to its original location. The advantage of LASEK is that the ablated corneal surface is covered by a full thickness epithelium immediately after surgery. It is hypothesised that this Epithelial coverage inhibits the wound healing response of the cornea. However, this concept will only work if the Epithelial cells are still vital after the exposure to alcohol. MATERIAL AND METHODS: The vitality of the corneal Epithelial cells was investigated in 6 human cadaver eyes after the exposure to 20 % alcohol over 15 to 60 s. The vitality of the corneal Epithelial cells was assessed by soaking the specimen in a 0.1 % trypan blue solution and incubated at 37 degrees C for 2 min. After a wash with BSS the specimen were re-incubated at 37 degrees C for 30 min in culture medium. After one more wash with BSS the cells were observed with a standard light microscope. Cells which retained the blue colour would be dead and vital cells would appear clear. Light microscopy and transmission electron microscopy was used to detect morphological changes. RESULTS: Mainly vital corneal Epithelial cells were seen for an alcohol exposure time of up to 30 s. In particular the basal Epithelial cells appeared alive. With a exposition time of 60 s most cells were dead. CONCLUSION: In LASEK the exposure time of 20 % alcohol is between 20 and 30 s. Based on our results we can conclude that after such exposure time most cells are alive, which is essential for the postoperative wound healing response.
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Laser Epithelial Keratomileusis (LASEK): histological investigation for vitality of corneal Epithelial cells after alcohol exposure
Klinische Monatsblatter Fur Augenheilkunde, 2002Co-Authors: Alexandra K Dreiss, Christoph Winkler Von Mohrenfels, B Gabler, John C Marshall, Thomas Kohnen, Chris P LohmannAbstract:Background: Laser Epithelial Keratomileusis (LASEK) is a new surgical procedure to treat myopia. An Epithelial flap is created after the exposure to 20% alcohol and following the Laser ablation the epithelium is repositioned to its original location. The advantage of LASEK is that the ablated corneal surface is covered by a full thickness epithelium immediately after surgery. It is hypothesised that this Epithelial coverage inhibits the wound healing response of the cornea. However, this concept will only work if the Epithelial cells are still vital after the exposure to alcohol. Material and methods: The vitality of the corneal Epithelial cells was investigated in 6 human cadaver eyes after the exposure to 20% alcohol over 15 to 60s. The vitality of the corneal Epithelial cells was assessed by soaking the specimen in a 0.1% trypan blue solution and incubated at 37°C for 2 min. After a wash with BSS the specimen were re-incubated at 37°C for 30 min in culture medium. After one more wash with BSS the cells were observed with a standard light microscope. Cells which retained the blue colour would be dead and vital cells would appear clear. Light microscopy and transmission electron microscopy was used to detect morphological changes. Results: Mainly vital corneal Epithelial cells were seen for an alcohol exposure time of up to 30 s. In particular the basal Epithelial cells appeared alive. With a exposition time of 60 s most cells were dead. Conclusion: In LASEK the exposure time of 20% alcohol is between 20 and 30 s. Based on our results we can conclude that after such exposure time most cells are alive, which is essential for the postoperative wound healing response.
