Posterior staphyloma is defined as a protrusion of the sclera posteriorly and is a hallmark of highly myopic eyes. It is a defect secondary to weakness and thinning of the scleral-uveal coat, leading to uveal protrusion. The mechanical strength of the sclera is determined by the number of cross-linkages between the collagen fibers. Collagen fibers of myopic eyes have fewer cross-linkages, which increases the elasticity of the scleral shell, causing it to stretch. The stretching is also associated with degenerative and neovascular lesions involving the retina and choroid, including chorioretinal atrophy, choroidal neovascularization, macular retinoschisis, and macular holes.
Posterior staphyloma is more commonly found in Asian adults older than 40 years of age, with a prevalence of 9%.
One classification of posterior staphylomas identified 10 different types based on their morphology.[2,3] However, these classifications were subjective and based on ophthalmoscopic drawings. Ohno-Matsui developed a more objective classification, which includes wide macular staphyloma, narrow macular staphyloma, peripapillary staphyloma, nasal staphyloma, inferior staphyloma, and other staphylomas. In one study, 74% of patients with posterior staphylomas were found to have wide macular staphylomas.
The older population of patients with staphyloma was found to have more severe visual disturbances and more commonly had chorioretinal changes.
Chorioretinal folds are a rare complication of myopic staphyloma. In one study, 1.3% of myopic eyes with posterior staphyloma were found to have chorioretinal folds. In highly myopic eyes, the choroid is thinner, and the directional force toward the steeper edge of the staphyloma results in the development of chorioretinal folds.
The visualization of posterior staphylomas has improved with the development of three-dimensional MRI. Still, staphylomas with mild curvatures are difficult to detect. Advances in OCT have enabled deeper penetration of tissues to attain enhanced images of the choroid, sclera, and optic nerve. Even staphylomas with a slight degree of outpouching can now be detected.
No specific treatment exists for posterior staphylomas.
One report of a patient with posterior staphyloma with associated serous retinal detachment noted successful treatment with scleral shortening. This technique alters the shape of the eye wall and enhances the integrity of the retinal pigment epithelium. However, the effect of scleral shortening appears to decrease with time, increasing the likelihood of recurrence.
Medscape Ophthalmology © 2017
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