Abstract
Abstract: :
Purpose. To evaluate the spatial relationships of the lamina cribrosa in highly myopic eyes. Methods. The study included 36 human globes with an axial length longer than 26.5 mm which either showed a marked glaucomatous optic nerve damage (n=29) (highly myopic glaucomatous group), or in which the optic nerve was neither affected by glaucoma nor any other disease (highly myopic normal group; n=7). Two non–highly myopic control groups included 53 globes enucleated due to malignant choroidal melanoma (n=42; non–highly myopic normal group), or enucleated due to painful absolute secondary angle–closure glaucoma (n=11; non–highly myopic glaucomatous group). Anterior–posterior histologic sections through the pupil and the optic disc were morphometrically evaluated. Results. In both highly myopic groups compared with both non–highly myopic groups, and within the highly myopic group, in the highly myopic glaucomatous group compared with the highly myopic normal group, lamina cribrosa was significantly (p<0.001) thinner. Correspondingly, the distance between the intraocular space and the cerebrospinal fluid space was significantly (p<0.05) shorter in the highly myopic normal group than in the non–highly myopic normal group, and in the highly myopic glaucomatous group compared with the highly myopic normal group. Conclusions. In highly myopic eyes, the lamina cribrosa is significantly thinner than in non–highly myopic eyes decreasing the distance between the intraocular space and the cerebrospinal fluid space and steepening the trans lamina pressure gradient at a given intraocular pressure. It may explain an increased glaucoma susceptibility in highly myopic eyes. As in non–highly myopic eyes, thinning of the lamina cribrosa gets more pronounced in highly myopic eyes if glaucoma is additionally present.
Keywords: optic disc • lamina cribrosa • myopia