Primary angle-closure glaucoma. Inheritance and environment.

The picture of primary angle-closure glaucoma accompanied by its shallow anterior chamber is so distinct that for many years it has evoked considerable curiosity concerning possible genetic determination. Family trees were published (Sedan and Sedan-Bauby, 1949; Waardenburg, I96I) and attempts were made to fit the inheritance into a genetic pattern-but without convincing success. Authors seemed to be more interested in studying selected families of special interest than in making a genetic enquiry into all their glaucoma cases (FranSois, 196I). Furthermore, many studies were made before the use of gonioscopy, which separated glaucoma into different types (Barkan, I938; Sugar, 1941). Later, discussion centred upon whether closed-angle or open-angle glaucoma occurred in the same families (Weekers, Gougnard-Rion, and Gougnard, 1955). One of the aims of these studies was to support the hypothesis that primary glaucoma is not a single disease; but with the realization that different forms of primary glaucoma can occur in the same individual, any reason to doubt that they could occur in the same families disappeared. In studying 8oo cases of primary angle-closure glaucoma, I have been impressed that, although acute angle-closure glaucoma is mostly an extremely distressing disease bringing eye damage to individuals, family histories of similar eye trouble are obtained very infrequently. In I964 I published the results of an enquiry (Lowe, I964); from 200 propositi 778 siblings were listed (395 brothers, 383 sisters) but only ten reports of glaucoma were given. Of the ten, three were considered to have had angle-closure glaucoma, four had chronic glaucoma with no acute episodes (and three of these were known to have open angles), and in three the type was unknown. Enquiry about eye disease among parents gave similar but less definite answers. Fifty propositi were questioned about consanguinity of parents, but there was only one cousin marriage. In the succeeding 6 years, with a study of a further 500 cases, my opinion has remained unaltered, namely-primary angle-closure glaucoma does occur within family membership but such occurrence is rare. This paper reviews the inheritance of primary angle-closure glaucoma, presents a new theory for the genetic components, and emphasizes the importance of effects from the environment.