Microspherophakia is a developmental abnormality in which the lens is small in diameter and spherical. The entire lens equator can be visualized at the slit lamp when the pupil is widely dilated (Fig 4-8). The spherical shape of the lens results in increased refractive power, which causes the eye to be highly myopic.
The cause of microspherophakia is believed to be faulty development of the secondary lens fibers during embryogenesis. Microspherophakia is most often seen as a part of Weill-Marchesani syndrome, but it may also occur as an isolated hereditary abnormality or, occasionally, in association with Peters anomaly, Marfan syndrome, Alport syndrome, Lowe syndrome, or congenital rubella. Individuals with Weill-Marchesani syndrome commonly have small stature, short and stubby fingers, and broad hands with reduced joint mobility. Weill-Marchesani syndrome is usually inherited as an autosomal recessive trait.
The spherical lens can block the pupil, causing secondary angle-closure glaucoma. Use of miotics aggravates this condition by increasing pupillary block and allowing additional forward lens displacement. Cycloplegics are the medical treatment of choice to break an attack of angle-closure glaucoma in patients with microspherophakia, because these agents decrease pupillary block by tightening the zonular fibers, decreasing the anteroposterior lens diameter, and pulling the lens posteriorly. A laser iridotomy may also be useful in relieving angle closure in patients with microspherophakia. (See also BCSC Section 10, Glaucoma.)
Figure 4-8 Microspherophakia. A, When the pupil is dilated, the entire lens equator can be seen at the slit lamp. B, Anterior dislocation of a microspherophakic lens.
(Part A courtesy of Karla J. Johns, MD.)
Excerpted from BCSC 2020-2021 series: Section 11 - Lens and Cataract. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.