RESUMO
BACKGROUND: The expected MRI-based dimensions of the intracranial optic nerve and optic tract in neonates are unknown. OBJECTIVE: To evaluate the sizes of the intracranial optic nerve and optic tract in neonates at term-equivalent age using MRI. MATERIALS AND METHODS: We retrospectively analyzed brain MRI examinations in 62 infants (28 boys) without intracranial abnormalities. The images were obtained in infants at term-equivalent age with a 1.5-tesla MRI scanner. We measured the widths and heights of the intracranial optic nerve and optic tract and calculated the cross-sectional areas using the formula for an ellipse. RESULTS: The means ± standard deviation of the width, height and cross-sectional area of the intracranial optic nerve were 2.7 ± 0.2 mm, 1.7 ± 0.2 mm and 3.5 ± 0.5 mm(2), respectively. The width, height and cross-sectional area of the optic tract were 1.5 ± 0.1 mm, 1.6 ± 0.1 mm and 2.0 ± 0.2 mm(2), respectively. Using univariate and multivariate analyses, we found that postmenstrual age showed independent intermediate positive correlations with the width (r = 0.48, P < 0.01) and cross-sectional area (r = 0.40, P < 0.01) of the intracranial optic nerve. The lower bounds of the 95% prediction intervals for the width and cross-sectional area of the intracranial optic nerve were 0.07 × (postmenstrual age in weeks) - 0.46 mm, and 0.17 × (postmenstrual age in weeks) - 4.0 mm(2), respectively. CONCLUSION: We identified the sizes of the intracranial optic nerve and optic tract in neonates at term-equivalent age. The postmenstrual age at MRI independently positively correlated with the sizes.
Assuntos
Imageamento por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/normas , Nervo Óptico/anatomia & histologia , Nervo Óptico/diagnóstico por imagem , Trato Óptico/anatomia & histologia , Trato Óptico/diagnóstico por imagem , Algoritmos , Pontos de Referência Anatômicos/anatomia & histologia , Pontos de Referência Anatômicos/diagnóstico por imagem , Feminino , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Recém-Nascido , Masculino , Tamanho do Órgão , Valores de Referência , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
We describe the visco-shell technique with sodium hyaluronate 2.3% (Healon5) to facilitate phacoemulsification in eyes with Morgagnian cataract. Because the entire nucleus is wrapped in a Healon5 visco-shell, phacoemulsification can be performed safely without damaging the corneal endothelium and the posterior capsule.