Objective: To determine the nature and course of ophthalmologic abnormalities and their clinical significance in Cohen syndrome.
Study design: Observational case series.
Participants: Twenty-two Cohen syndrome patients aged 2 to 57 years were examined, and a retrospective review of ophthalmologic records was carried out for 14 of them. All but one were part of the Finnish study of refined mapping of the Cohen syndrome gene by linkage disequilibrium in chromosome 8.
Main outcome measures: Visual acuity (VA), cycloplegic refraction, biomicroscopy, lens opacitometry, ophthalmoscopy, and fundus photography.
Results: With the exception of the two youngest patients, all had symptoms such as nyctalopia, impaired vision, and visual field loss. Progressive, often high-grade myopia, astigmatism, and retinochoroidal dystrophy resembling retinitis pigmentosa occurred in all, except for the youngest patients. The earliest fundus changes were pale disc and pale fundus with or without pigment granularity, followed by narrowed vessels, pigment clumps, and bone spiculelike pigment accumulations by 10 to 20 years of age. Pigment deposits increased and approached the posterior pole by 35 to 40 years of age. Patients more than 45 years of age had severe retinochoroidal atrophy. A bull's-eye macula was seen in most patients. Teenagers had peripheral lens opacities, and young adults had early nuclear sclerosis confirmed by lens opacitometry. Older patients also had posterior subcapsular cataracts, iris atrophy, and iridophacodonesis. Vision started to deteriorate at the age of 6 to 10 years, but remained relatively good (VA 0.5-0.1) in most patients until 30 and, in one case, 46 years of age. Older patients were severely visually handicapped (VA hand motion to light perception), but none were completely blind.
Conclusions: Progressive myopia and retinochoroidal dystrophy are essential features in Cohen syndrome and, together with early lens opacities, lead to deterioration of vision. Cohen syndrome patients need careful ophthalmologic follow-up at all ages. Nyctalopia and restricted visual fields should be considered when planning the patient's daily activities.