Nanophthalmos is a rare, usually bilateral, developmental disorder characterized by an eye with short axial length, a normal or slightly enlarged lens, thickened sclera, hyperopia, foveal changes, and a predisposition to uveal effusions and angle-closure glaucoma. The criteria for nanophthalmos differ in various studies, but in most, the size criterion is an axial length between 19 and 21 mm. For clinical purposes, 20.5 mm is often used as the cutoff. Nanophthalmos has a strong genetic basis, but sporadic cases (likely representing new mutations) occur.
Examination of tissue from nanophthalmic eyes has shown disarrangement, fraying, and splitting of scleral collagen fibrils. Abnormalities in the extracellular matrix glycosaminoglycans have also been described. These scleral changes may predispose the nanophthalmic eye to uveal effusion due to reduced protein permeability and impaired venous outflow through the vortex veins.
See BCSC Section 6, Pediatric Ophthalmology and Strabismus, and Section 10, Glaucoma, for additional discussion of nanophthalmos.
Carricondo PC, Andrade T, Prasov L, Ayres BM, Moroi SE. Nanophthalmos: a review of the clinical spectrum and genetics. J Ophthalmol. 2018 May 9;2018:2735465.
Fukuchi T, Sawada H, Seki M, Oyama T, Cho H, Abe H. Changes of scleral-sulfated proteoglycans in three cases of nanophthalmos. Jpn J Ophthalmol. 2009;53(2):171–175.
Excerpted from BCSC 2020-2021 series: Section 4 - Ophthalmic Pathology and Intraocular Tumors. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.