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Abstract

Neste projeto estamos desenvolvendo instrumento para medidas das aberrações de frente de onda do olho humano usando um sensor Hartmann-Shack. Uma fonte de luz laser é direcionada ao olho e sua reflexão difusa na retina gera frente de onda aproximadamente esférica dentro do olho. Esta frente de onda atravessa os diferentes componentes do olho (humor vítreo, lente, humor aquoso e córnea) trazendo informações sobre as aberrações ópticas causadas por estes componentes. No meio externo ao olho existe sistema óptico formado por uma matriz de microlentes e uma câmera CCD. A frente de onda incide nesta matriz e forma um padrão aproximadamente matricial de "spots" no plano do CCD. Algoritmos de processamento de imagens são utilizados para detectar os centróides de cada "spot" e esta informação é utilizada para deduzir a forma da frente de onda usando métodos de aproximação por mínimos quadrados e polinômios de Zernike. Descrevemos aqui detalhes da primeira fase deste projeto, em que foi realizada a construção da primeira geração de instrumentos protótipos e testes preliminares em olho artificial, calibrado com diferentes ametropias, i. e., miopia, hipermetropia e astigmatismo.

Keywords: Topografia da córnea; Técnicas de diagnóstico oftalmológico; Astigmatismo; Desenho de equipamento; Optometria; Retina; Processamento de imagem assistida por computador

Abstract

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Abstract

PURPOSE: The purpose of this study is to look into the relationship between tear film osmolarity, tear crystallization, and corneal esthesiometry findings in Sjögren's syndrome patients.
METHODS: This cross-sectional observational study included 43 eyes from patients with a confirmed diagnosis of Sjögren's syndrome. Tear osmolarity was measured with an iPen osmometer, tear crystallization was graded using Roland's classification, and corneal sensitivity was evaluated with a Cochet–Bonnet aesthesiometer. Ocular symptoms were assessed using the Ocular Surface Disease Index questionnaire. Patients who had undergone keratoplasty or worn contact lenses within 4 hours of testing were excluded.
RESULTS: The cohort's mean tear osmolarity was 292.5±15.0 mOsm/L (median: 293 mOsm/L, IQR: 17.5). There was no significant difference between patients with primary Sjögren's syndrome (mean: 289.4 mOsm/L) and those with secondary Sjögren's syndrome (mean: 294.5 mOsm/L; p=0.413). Tear crystallization patterns were more severe in patients with primary Sjögren's syndrome (mean: 3.25, median: 3.5, IQR: 1.25) than in those with secondary Sjögren's syndrome (mean: 3.19, median: 3.0, IQR: 1.0), though the difference was not statistically significant (p=0.87). Corneal sensitivity was reduced by 3.5±1.7 mm (median: 4.0 mm, IQR: 2.13). Tear crystallization has a significant negative correlation with corneal sensitivity (r=−0.313, p=0.041), suggesting that poorer tear quality leads to decreased corneal sensitivity.
CONCLUSION: Tear crystallization patterns and corneal sensitivity were found to be significantly correlated in Sjögren's syndrome patients. The findings also indicate that systemic medication use may affect tear film quality.

Keywords: Sjogren's syndrome, Tear crystallization, Dry eye disease, Cornea, Tears, Osmolarity