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Last Month’s Blink

Ectopia Lentis in a Patient With Homocystinuria

Written by Deepa Taranath, MBBS, MS, FRANZCO. Photograph by Angela Chappell, CRA, OCT-C. Both are at Flinders Medical Centre Ophthalmology Department, Adelaide, Australia.

A 9-year-old girl had been diagnosed with homocystinuria as an infant and, over the years, had ophthalmic screening for ocular associations of the disorder. She was found to have bilateral inferior subluxation of clear lenses. By age 9, the subluxation had progressively wors­ened (see photo) such that it was affecting her aided vision significantly. Her visual acuity was 20/63 in the right eye and 20/50 in the left.

Homocystinuria is an autosomal recessive inherited disorder of methionine metabolism due to deficiency of cystathionine beta-synthase. The zonule normally contains high levels of cystine, and a deficiency of this amino acid leads to in­creased fragility of the zonular fibers, which then alters the lens stability.

Of interest in this photograph of the right eye are the curly ends of the broken zonular fibers seen at the lens equator of the subluxated lens.

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