Microphthalmia-retinitis pigmentosa-foveoschisis-optic disc drusen syndrome is a rare, genetic, non-syndromic developmental defect of the eye disorder characterized by the association of posterior microphthalmia, retinal dystrophy compatible with retinitis pigmentosa, localized foveal schisis and optic disc drusen. Patients present high hyperopia, usually adult-onset progressive nyctalopia and reduced visual acuity, and, on occasion, acute-angle glaucoma.

Autosomal recessive isolated posterior microphthalmos defines a rare distinct phenotype restricted to the posterior segment of the eye. In adults, it is clinically characterized by extreme hyperopia (from +7.5 to +21 diopters) due to short axial length (14 mm to 20 mm; normal is greater than 21 mm). Other features include an essentially normal anterior segment, steep corneal curvatures, shallow anterior chamber, thick lenses, and thickened scleral wall. The palpebral fissures appear narrow because of relatively deep-set eyes, visual acuity is mildly to moderately reduced, and anisometropic or strabismic amblyopia is common. The fundus of the eye shows crowded optical discs, tortuous vessels, and an abnormal foveal avascular zone; in addition, papillomacular folds are often reported. Morphometric features of the small eyes predispose to complications such as narrow-angle glaucoma and uveal effusion (summary by Gal et al., 2011). For a general phenotypic description and a discussion of genetic heterogeneity of isolated microphthalmia, see MCOP1 (251600).