Toric intraocular lenses (IOLs) are designed to reduce spectacle dependency by correcting corneal astigmatism at the time of surgery. However, these IOLs are reliant on the accurate prediction of post-operative corneal astigmatism through reliable ocular biometry and the accurate calculation of surgically induced astigmatism. In the thesis the repeatability of assessing corneal curvature was assessed using six commercially available keratometers. The results question the validity of corneal biometry and infer that much of the apparent change in corneal shape usually associated with surgically induced astigmatism may be due to measurement error. The use of the oblique cross cylinder formulae for the calculation of post-operative corneal curvature was also investigated. This formula is incorporated into all commercially available toric IOL calculators and is utilised in every toric IOL implantation. The results from this thesis indicate that the formula is not applicable to the human cornea and that the use of the calculator does not increase the effectivity of the toric correction. Furthermore, the thesis queries the assumption that post-operative corneal astigmatism is directly proportional to post-operative refractive error. The disparity between both the magnitude and axis of astigmatism measured by keratometry and manifest refraction in a pseudophakic population was investigated. The axis measurements in particular showed very poor agreement; far outside an acceptable level of misalignment, significantly decreasing the effective correction provided if the lens was aligned with the keratometry readings. Inclusion of the posterior corneal curvature and thickness, along with a smaller chord length may lead to a more accurate assessment of corneal power. Despite the difficulty in providing an effective toric IOL correction, it was found that the correction of corneal astigmatism at the time of cataract surgery might decrease the risks of falls. Uncorrected astigmatism and cataract both cause a reduction in stability when stepping oven an obstacle, which is one of the most common causes of trips and falls in the elderly population.

INTRODUÇÃO: A presbiopia pseudofácica, imposta pela extração do cristalino e implantação de uma lente intraocular monofocal, representa uma relativa limitação da cirurgia de catarata moderna. Diversos métodos para compensação de tal fenômeno já foram descritos. Nesse estudo, avaliamos a eficácia de um implante intraocular estenopeico em promover ampliação da profundidade de foco, e seu impacto no desempenho visual. MÉTODOS: Foram selecionados 10 pacientes hígidos, com boa saúde ocular, previamente submetidos a cirurgia de catarata bilateral com implante de lente intraocular monofocal, os quais apresentavam limitação da acuidade visual para perto. Os pacientes foram submetidos a implantação monocular do diafragma intraocular estenopeico XtraFocus®, no sulco ciliar. As variáveis avaliadas foram acuidade visual, refração subjetiva, sensibilidade ao contraste, amplitude de pseudoacomodação (curva de defocus), estereopsia, campimetria computadorizada, teste de efeito Pulfrich, e avaliação subjetiva do desempenho visual, através da aplicação de questionário. RESULTADOS: Houve significativa melhora da acuidade visual para perto, com 7 pacientes alcançando acuidade visual sem correção para perto de 20/30, no olho operado. Não houve impacto significativo na refração subjetiva, sensibilidade ao contraste e estereopsia. A perimetria computadorizada evidenciou redução de sensibilidade retiniana difusa, no olho operado. A percepção subjetiva do desempenho visual após o tratamento foi favorável, com impacto positivo nas atividades diárias. Não foi observada indução de efeito Pulfrich. CONCLUSÕES: O implante estenopeico estudado foi capaz de promover ampliação da profundidade de foco, com aprimoramento da acuidade visual para perto. O implantação cirúrgica se mostrou segura, sem ocorrência de eventos adversos significativos. Os resultados sugerem que uma maior independência de óculos pode ser alcançada caso a técnica seja aplicada em pacientes portadores de miopia de pequena magnitude. Este achado está em conformidade com trabalhos prévios envolvendo dispositivos estenopeicos. Apesar da limitação à entrada de luz imposta pelo orifício estenopeico, a percepção de luminosidade não é proporcionalmente impactada. Entretanto, em condições de baixa luminosidade, pode haver uma percepção monocular de escuridão / INTRODUCTION: Pseudophakic presbyopia, imposed by crystalline lens extraction and implantation of an artificial monofocal intraocular lens (IOL), represents a relative limitation of modern cataract surgery. Several methods of compensation of this phenomenon have been proposed. In this study, we evaluate the efficacy of a pinhole intraocular implant in promoting depth of focus extension, and its impact in visual performance. METHODS: A selection of 10 healthy patients, with no ocular comorbidity, previously submitted to bilateral cataract surgery and monofocal IOL implantation, presenting with near vision limitation, was carried out. Patients underwent monocular implantation of the XtraFocus® pinhole implant, in the ciliary sulcus. Outcome variables were visual acuity, subjective refraction, contrast sensitivity, amplitude of pseudoaccommodation (defocus curve), stereoacuity, automated perimetry, Pulfrich effect testing and subjective visual performance evaluation with a questionnaire. RESULTS: A significant improvement in near visual acuity was observed, with 7 patients reaching 20/30 uncorrected near visual acuity, in the operated eye. There was no significant impact in subjective refraction, contrast sensitivity and stereoacuity. Automated perimetry revealed a reduction of overall retinal sensitivity, in the operated eye. Subjective assessment of visual performance was favourable, with positive impact in daily activities. Induction of Pulfrich effect was not observed. CONCLUSIONS: The pinhole implant evaluated in this study was able to provide depth of focus extension, and enhance near visual acuity. Surgical implantation was safe, with no occurrence of significant adverse events. Results suggest that a greater level of spectacle independence may be achieved if this approach is combined with low levels of myopia. This finding is in accordance with other studies involving small aperture optics. In spite of the reduction of light entrance caused by the pinhole implant, the overall brightness sensation is not proportionally impaired. However, under low light conditions, a monocular darkening perception can occur

Orientadores: Vital Paulino Costa, Carlos Eduardo Leite Arieta / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-23T19:38:14Z (GMT). No. of bitstreams: 1 MassaResende_Graziela_D.pdf: 3242400 bytes, checksum: e2f62de85f9ba384fc976b9263cd9197 (MD5) Previous issue date: 2013 / Resumo: O presente estudo tem como objetivos investigar a variação da espessura corneana central (ECC) e da pressão intraocular (PIO) em crianças após cirurgia de catarata congênita, bem como fatores de risco associados com essas mudanças. Vinte e seis crianças com catarata congênita foram recrutadas prospectivamente antes da cirurgia para remoção da mesma. Trinta e sete olhos foram analisados. Todos pacientes foram submetidos a exame oftalmológico completo com avaliação da PIO e da ECC antes da cirurgia e 6, 12, 18, 24 e 36 meses após o procedimento cirúrgico, pelo mesmo observador. A paquimetria ultrassônica foi realizada com o aparelho Ocuscan RXP (Alcon Laboratories Inc, USA), e a tonometria foi realizada com o tonômetro de aplanação de Goldmann modelo R900 (Haag-Streit, Koeniz, Suíça) ou tonômetro de aplanação de Perkins (Clement Clark International ltd, Londres, Inglaterra). Dos 37 olhos, 15 tornaram-se afácicos e 22, pseudofácicos. A ECC média aumentou significativamente de 556,24 ± 44,19 ?m para 585,07 ± 56,45 ?m (p = 0,025) ao final de três anos, enquanto a PIO média aumentou significativamente de 12,05 ± 2,3 mmHg para 13,96 ± 2,99 mmHg (p = 0,005). Olhos afácicos foram submetidos à cirurgia em uma idade mais precoce (15,16 ± 32,02 meses) em comparação aos olhos pseudofácicos (71,48 ± 53,14 meses) (p <0,001). Após três anos, a média de variação da ECC, nos olhos afácicos (56,10 ± 46,97 ?m), foi significativamente maior que nos olhos pseudofácicos (12,71 ± 38,41 ?m) (p = 0,015). Encontramos correlação negativa entre a idade no momento da cirurgia e a variação da ECC (r = -0,34, p = 0,04), mas não entre idade e variação da PIO (r = -0,18, p = 0,27). Quando a cirurgia foi realizada entre 0 e 1 ano de idade, a média de variação da ECC, em três anos, foi de 69,0 ± 40,3 ?m, em comparação com 1,0 ± 23,17, -20,0 ± 8,04 e 34,25 ± 40,11 ?m quando as cirurgias foram realizadas de 1 a 5, 5 a 10 e > 10 anos, respectivamente (p <0,001). Não houve correlação da variação da PIO com a variação da ECC (r = 0,31, p = 0,06). Concluímos que a ECC aumenta nos olhos submetidos à cirurgia de catarata congênita, especialmente quando a cirurgia é realizada em uma idade precoce / Abstract: The present study aims to investigate the variation of central corneal thickness (CCT) and intraocular pressure (IOP) in children after congenital cataract surgery, as well as risk factors associated with these changes. Twenty-six children with congenital cataract were prospectively recruited prior to surgery. Thirty-seven eyes were analyzed. All patients underwent a complete ophthalmic examination with assessment of IOP and CCT before surgery and 6, 12, 18, 24 and 36 months after surgery by the same observer. Ultrasonic pachymetry was performed with the handset unit Ocuscan RXP (Alcon Laboratories Inc, USA) and tonometry was performed with the Goldmann applanation tonometer model R900 (Haag-Streit, Koeniz, Switzerland) or the Perkins applanation tonometer (Clement Clark International Ltd, London, England). Among the 37 eyes, 15 became aphakic and 22 pseudophakic. The mean CCT increased significantly from 556.24 ± 44.19 ?m to 585.07 ± 56.45 ?m (p = 0.025) at the end of three years, while the mean IOP increased significantly from 12.05 ± 2.3 mmHg to 13, 96 mmHg ± 2.99 (p = 0.005). Aphakic eyes underwent surgery at an earlier age (15.16 ± 32.02 months) compared with pseudophakic eyes (71.48 ± 53.14 months) (p <0.001). After three years, the mean CCT change in aphakic eyes (56.10 ± 46.97 ?m) was significantly higher than in pseudophakic eyes (12.71 ± 38.41 ?m) (p = 0.015). Age at the time of surgery was inversely correlated to CCT change (r = -0.34, p= 0.04), but not to IOP change (r=-0.18, p= 0.27). When surgery was performed between 0 and 1 year of age, the mean CCT change in 3 years was 69.0 ± 40.03 ?m, compared with 1.0 ± 23.17, -20.0 ± 6.56 and 34.25 ± 40.11 ?m when the surgeries were performed between 1-5, 5-10 and > 10 years, respectively (p <0.001). There was no correlation between IOP change and CCT change (r = 0.31, p = 0.06). We conclude that CCT increases in eyes undergoing congenital cataract surgery, especially when the surgery is performed at an early age / Doutorado / Oftalmologia / Doutora em Ciências Médicas

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