Pupil-block glaucoma in homocystinuria.

HOMOCYSTINURIA is an inborn error of metabolism due to deficiency of the enzyme cystathionine synthetase. This results in an increased excretion of homocystine in the urine and raised homocystine and methionine levels in the blood and cerebrospinal fluid. Clinically there is a picture of ectopia lentis, due to zonular degeneration, skeletal changes, fine fair hair, shuffling gait, mental retardation, and thrombo-embolic episodes. The first and last of these findings can pose very difficult problems for the ophthalmologist as will be seen from the reported cases. The mode of inheritance of this condition is known to be of the autosomal recessive type. It was first described by Field, Carson, Cusworth, Dent, and Neill (1962) in Northern Ireland and a clinical and pathological review of ten cases was made in 1965. All had ectopia lentis. Several cases have since been described in the United Kingdom and United States of America, and since 1965 four further cases have been discovered in Northern Ireland. Three of these first presented as ophthalmological problems with pupil-block glaucoma. A previously described case reported by Arnott and Greaves (1964) has since had bilateral lens extractions for pupil-block glaucoma, and another case described as Marfan's syndrome with bilateral secondary glaucoma (reported by Martin and Cowan, 1960) is reviewed. Lieberman, Podos, and Hartstein (1966) described two cases in which the history and findings of bilateral dislocation of the lenses associated with pupil-block glaucoma led to the recognition of homocystinuria. In five cases described in this paper nine eyes had this condition and six lens extractions were carried out. The following case histories illustrate the difficulties in treatment and management.