Lasers have been involved in Ophthalmology in the treatment of myopia and hyperopia for several years. Laser systems have transformed patients‟ quality of life, freeing them from the need for glasses, as in the case of LASIK. Ultrafast lasers have played an important role in surgery of the eye. In LASIK, they are used to cut the flap that is lifted to expose the stroma for UV Excimer laser treatment of this region. They are now being used for surgery deeper into the eye,for instance, treating the lens as part of treatments for cataract surgery. The use of ultrafast lasers in cataract surgery and how they can be applied to achieve better surgical outcomes is the focus of this work. It reports on an investigation of laser interaction at and near the anterior of the lens, in particular the boundary between the fibrous mass, capsule, and anterior chamber of the eye. The study reviews the biomechanics of the eye, develops an interaction model with lens tissue, and reports for the first time clinically studies using ex vivo testing of porcine eyes. The components of the treatment laser system are described along with the requirements. Results of the experiments are outlined and discussed, followed by a summary and conclusions including discussion of areas for further research.

Objetivos: Determinar os efeitos celulares e o mecanismo de ação da mitomicina C tópica na prevenção e tratamento da opacidade corneana em coelhos submetidos à ceratectomia fotorrefrativa (PRK). Métodos: Foram submetidos à cirurgia de PRK 224 coelhos para correção de -9 dioptrias esféricas, associada à aplicação de mitomicina C tópica ou solução salina balanceada. O nível de opacidade corneana foi avaliado por meio de análise à lâmpada de fenda. Os animais foram sacrificados quatro horas, 24 horas, quatro semanas e seis meses após a cirurgia. A análise imunohistoquímica foi realizada com as técnicas de TUNEL e foram utilizados os anticorpos Ki67 e alpha-SMA para a análise da apoptose celular, replicação celular e formação de miofibroblastos, respectivamente. Resultados: Todos os grupos submetidos à aplicação de mitomicina C apresentaram um maior número de células positivamente marcadas pelo ensaio com TUNEL (indicando maior taxa de apoptose celular) e um menor número de células positivamente marcadas pelo anticorpo Ki67 (indicando menor taxa de replicação celular). Uma menor quantidade de miofibroblastos (células positivamente marcadas pelo anticorpo alpha-SMA) foi identificada após a aplicação profilática da mitomicina C, comparada com sua aplicação com finalidade terapêutica. Além disso, identificou-se uma zona de acelularidade no estroma anterior de córneas tratadas com mitomicina C, persistente por um período mínimo de seis meses. Conclusões: A aplicação da mitomicina C diminuiu signficativamente a formação de opacidade corneana em coelhos. Apesar da mitomicina C ter induzido uma maior apoptose de ceratócitos e miofibroblastos, seu principal mecanismo de ação, responsável pela prevenção da opacidade corneana, decorreu do bloqueio da replicação dos ceratócitos ou outras linhagens celulares progenitoras dos miofibroblastos. A aplicação da mitomicina C na concentração de 0,002% mostrou-se tão eficiente quanto sua aplicação na concentração de 0,02%. Não obstante, uma persistente diminuição da densidade de ceratócitos no estroma anterior pode representar um sinal de alerta para possíveis complicações a longo prazo / Purpose: To determine cellular effects and the mechanism through which topical mitomycin C prevents and treats corneal haze after photorefractive keratectomy (PRK) in rabbits. Methods: Minus nine diopters PRK with mitomycin C or balanced salt solution was performed in two hundred and twenty four New Zealand rabbits. Haze level was graded at the slit lamp. Rabbits were sacrificed at 4 hours, 24 hours, 4 weeks or 6 months after surgery and immunohistochemistry was performed with TUNEL assay, Ki67 and alpha-SMA to analyze keratocyte cells apoptosis, keratocyte cells replication and myofibroblast cells formation, respectively. Results: TUNEL-positive cells increased in all mitomycin C groups (representing more keratocyte cells undergoing apoptosis) while Ki67-positive cells decreased significanlty (representing a decreased keratocyte cells replication) following mitomycin C application. A greater decrease in myofibroblasts was noted with prophylactic mitomycin C treatment than therapeutic mitomycin C treatment. There was, however, an anterior stromal acellular zone in eyes treated with mitomycin C that persisted out to the maximum follow-up of 6 months. Conclusion: Mitomycin C application significantly reduced corneal haze formation in rabbits. Its treatment induces apoptosis of keratocytes and myofibroblasts, but the predominate effect in inhibiting or treating haze appears to be at the level of blocked replication of keratocytes or other progenitor cells of myofibroblasts. Treatment with 0.002% mitomycin C appears to be just as effective as higher concentrations (0.02%) in the rabbit model. However, a persistent decrease in keratocyte cells density in the anterior stroma could be a warning sign for future complications

Thesis (M.S.)--University of Adelaide, Dept. of Surgery, 2004. / "December 2003" Bibliography: leaves 82-99.

Objetivos: Determinar os efeitos celulares e o mecanismo de ação da mitomicina C tópica na prevenção e tratamento da opacidade corneana em coelhos submetidos à ceratectomia fotorrefrativa (PRK). Métodos: Foram submetidos à cirurgia de PRK 224 coelhos para correção de -9 dioptrias esféricas, associada à aplicação de mitomicina C tópica ou solução salina balanceada. O nível de opacidade corneana foi avaliado por meio de análise à lâmpada de fenda. Os animais foram sacrificados quatro horas, 24 horas, quatro semanas e seis meses após a cirurgia. A análise imunohistoquímica foi realizada com as técnicas de TUNEL e foram utilizados os anticorpos Ki67 e alpha-SMA para a análise da apoptose celular, replicação celular e formação de miofibroblastos, respectivamente. Resultados: Todos os grupos submetidos à aplicação de mitomicina C apresentaram um maior número de células positivamente marcadas pelo ensaio com TUNEL (indicando maior taxa de apoptose celular) e um menor número de células positivamente marcadas pelo anticorpo Ki67 (indicando menor taxa de replicação celular). Uma menor quantidade de miofibroblastos (células positivamente marcadas pelo anticorpo alpha-SMA) foi identificada após a aplicação profilática da mitomicina C, comparada com sua aplicação com finalidade terapêutica. Além disso, identificou-se uma zona de acelularidade no estroma anterior de córneas tratadas com mitomicina C, persistente por um período mínimo de seis meses. Conclusões: A aplicação da mitomicina C diminuiu signficativamente a formação de opacidade corneana em coelhos. Apesar da mitomicina C ter induzido uma maior apoptose de ceratócitos e miofibroblastos, seu principal mecanismo de ação, responsável pela prevenção da opacidade corneana, decorreu do bloqueio da replicação dos ceratócitos ou outras linhagens celulares progenitoras dos miofibroblastos. A aplicação da mitomicina C na concentração de 0,002% mostrou-se tão eficiente quanto sua aplicação na concentração de 0,02%. Não obstante, uma persistente diminuição da densidade de ceratócitos no estroma anterior pode representar um sinal de alerta para possíveis complicações a longo prazo / Purpose: To determine cellular effects and the mechanism through which topical mitomycin C prevents and treats corneal haze after photorefractive keratectomy (PRK) in rabbits. Methods: Minus nine diopters PRK with mitomycin C or balanced salt solution was performed in two hundred and twenty four New Zealand rabbits. Haze level was graded at the slit lamp. Rabbits were sacrificed at 4 hours, 24 hours, 4 weeks or 6 months after surgery and immunohistochemistry was performed with TUNEL assay, Ki67 and alpha-SMA to analyze keratocyte cells apoptosis, keratocyte cells replication and myofibroblast cells formation, respectively. Results: TUNEL-positive cells increased in all mitomycin C groups (representing more keratocyte cells undergoing apoptosis) while Ki67-positive cells decreased significanlty (representing a decreased keratocyte cells replication) following mitomycin C application. A greater decrease in myofibroblasts was noted with prophylactic mitomycin C treatment than therapeutic mitomycin C treatment. There was, however, an anterior stromal acellular zone in eyes treated with mitomycin C that persisted out to the maximum follow-up of 6 months. Conclusion: Mitomycin C application significantly reduced corneal haze formation in rabbits. Its treatment induces apoptosis of keratocytes and myofibroblasts, but the predominate effect in inhibiting or treating haze appears to be at the level of blocked replication of keratocytes or other progenitor cells of myofibroblasts. Treatment with 0.002% mitomycin C appears to be just as effective as higher concentrations (0.02%) in the rabbit model. However, a persistent decrease in keratocyte cells density in the anterior stroma could be a warning sign for future complications

A retrospective case study of 3 patients that developed epithelial ingrowth after laser in situ keratomileusis (LASIK). This study was conducted at Boston Eye Group in Brookline, Massachusetts. The Oculus Pentacam was used to study corneal densitometry for each patient. Corneal densitometry readings were obtained for each patient pre-operatively and post-operatively after ingrowth was discovered. Densitometry was recorded at the central nest of opacity and at the leading edges of the ingrowth. For all patients, the most severe stages of epithelial ingrowth observed on slit lamp photographs correlated to the highest densitometry readings, with peak densitometry ranging from 73.3 - 95.1. These values were much higher than pre-operative densitometry readings, which ranged from 21.8 - 27.2. In two cases, the Pentacam densitometry map revealed progression of ingrowth towards the visual axis that was only faintly detectable or not detectable at all on corresponding slit lamp photographs. Corneal densitometry can be used as an objective measure of the severity and progression of epithelial ingrowth.

Doctor of Philosophy (PhD) Orthoptics / The aim of this study was to evaluate the safety and efficacy of LASIK as a refractive surgical procedure, using a repeated measures design to assess satisfaction of patients who had LASIK and to correlate clinical outcomes with detailed measures of patient satisfaction to document long-term viability, monitor changes over time and patients’ functional abilities post-operatively. Method In the study 216 post-LASIK subjects were randomly selected from among patients who underwent simultaneous bilateral LASIK using the Chiron Technolas 217C plano-scan excimer laser with the Chiron ACS (Automated Corneal Shaper) and the Hansatome microkeratome. The subjects were recruited from within one centre, and the procedures were performed by any one of three surgeons. The study also included 100 non-LASIK subjects as a control group, to compare and differentiate ocular symptoms and visual difficulties between LASIK and non-LASIK patients. Clinical data documented included visual acuity, subjective refraction, record of glasses and/or contact lenses prescription, corneal topography with EyeSys and Orbscan, slit lamp examination, surgical details, and any pre-existing eye disease/conditions and previous surgery or injury that might prevent the subjects from achieving their desired visual outcome post-operatively. Subjective patient satisfaction evaluation of the treatment group was assessed by subjects completing a survey questionnaire at 3 months, 6 months, 12 months and 24 months post-operatively. The control group subjects completed a comparable questionnaire and were assessed at baseline and 3 months later. Because the control group subjects did not have any surgical alterations, it was unnecessary for them to have more than one follow-up. Results LASIK achieved relatively high patient satisfaction, with only a small number of dissatisfied patients. It was effective in correcting myopia, hyperopia and astigmatism. However, there was some persistent under-correction in myopic spherical and minus cylindrical refractive errors. Hyperopic spherical correction was less effective, as there were more under- as well as over-correction, and the plus cylindrical correction tended to be under-corrected. The LASIK subjects’ post-operative distance uncorrected visual acuity was not as good as their pre-operative best corrected visual acuity, but it did not significantly correlate with patient satisfaction. The findings were consistent with other studies and confirmed the concept that patient satisfaction is not unidimensional and is not related to outcome solely in terms of visual acuity and residual refractive errors. Other contributing factors included problems with glare, rating of unaided distance and near vision, ability to drive at night, change in ability to perform social/recreational, home and work activities, change in overall quality of life, amount of information given prior to surgery, rating of surgery success, and surgery outcome relative to pre-operative expectations. These variables demonstrated distinctive differences between subjects who were satisfied and dissatisfied. Conclusions The findings of this study are consistent with those of earlier studies. However, the repeated measures design and the comparisons between LASIK subjects and the control group revealed some new insights that were previously undocumented. LASIK achieved high patient satisfaction, and factors associated with satisfaction were predictable, but sources of dissatisfaction were more idiosyncratic and contributing factors were identified.

Doctor of Philosophy (PhD) Orthoptics / The aim of this study was to evaluate the safety and efficacy of LASIK as a refractive surgical procedure, using a repeated measures design to assess satisfaction of patients who had LASIK and to correlate clinical outcomes with detailed measures of patient satisfaction to document long-term viability, monitor changes over time and patients’ functional abilities post-operatively. Method In the study 216 post-LASIK subjects were randomly selected from among patients who underwent simultaneous bilateral LASIK using the Chiron Technolas 217C plano-scan excimer laser with the Chiron ACS (Automated Corneal Shaper) and the Hansatome microkeratome. The subjects were recruited from within one centre, and the procedures were performed by any one of three surgeons. The study also included 100 non-LASIK subjects as a control group, to compare and differentiate ocular symptoms and visual difficulties between LASIK and non-LASIK patients. Clinical data documented included visual acuity, subjective refraction, record of glasses and/or contact lenses prescription, corneal topography with EyeSys and Orbscan, slit lamp examination, surgical details, and any pre-existing eye disease/conditions and previous surgery or injury that might prevent the subjects from achieving their desired visual outcome post-operatively. Subjective patient satisfaction evaluation of the treatment group was assessed by subjects completing a survey questionnaire at 3 months, 6 months, 12 months and 24 months post-operatively. The control group subjects completed a comparable questionnaire and were assessed at baseline and 3 months later. Because the control group subjects did not have any surgical alterations, it was unnecessary for them to have more than one follow-up. Results LASIK achieved relatively high patient satisfaction, with only a small number of dissatisfied patients. It was effective in correcting myopia, hyperopia and astigmatism. However, there was some persistent under-correction in myopic spherical and minus cylindrical refractive errors. Hyperopic spherical correction was less effective, as there were more under- as well as over-correction, and the plus cylindrical correction tended to be under-corrected. The LASIK subjects’ post-operative distance uncorrected visual acuity was not as good as their pre-operative best corrected visual acuity, but it did not significantly correlate with patient satisfaction. The findings were consistent with other studies and confirmed the concept that patient satisfaction is not unidimensional and is not related to outcome solely in terms of visual acuity and residual refractive errors. Other contributing factors included problems with glare, rating of unaided distance and near vision, ability to drive at night, change in ability to perform social/recreational, home and work activities, change in overall quality of life, amount of information given prior to surgery, rating of surgery success, and surgery outcome relative to pre-operative expectations. These variables demonstrated distinctive differences between subjects who were satisfied and dissatisfied. Conclusions The findings of this study are consistent with those of earlier studies. However, the repeated measures design and the comparisons between LASIK subjects and the control group revealed some new insights that were previously undocumented. LASIK achieved high patient satisfaction, and factors associated with satisfaction were predictable, but sources of dissatisfaction were more idiosyncratic and contributing factors were identified.

Thesis (Ph. D.)--University of New South Wales, 2004. / Also available online.

Thesis (Ph. D.)--University of Sydney, 2007. / Title from title screen (viewed Mar. 22, 2007). Includes tables and questionnaires. Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Applied Vision Sciences. Includes bibliographical references. Also issued in print.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains x, 100 p.; also includes graphics. Includes bibliographical references (p. 91-100).