AGE-RELATED BRUCH MEMBRANE CHANGE - A CLINICAL-STUDY OF THE RELATIVE ROLE OF HEREDITY AND ENVIRONMENT

For many years there has been controversy concerning the role of genet ic influences in the pathogenesis of age-related macular disease. It i s widely believed that the lesions causing visual loss occur in respon se to age-related changes in Bruch's membrane which are recognised cli nically as drusen. In this study the density, size, and confluence of drusen as shown on colour photographs were compared in eyes of 50 spou ses and 53 sibling pairs ascertained during a prospective study of age -related macular disease. Concordance between pairs of drusen - number , size, and density - were determined by kappa statistic and chi2 test for trend. Drusen were absent in one sibling and 26 spouses of patien ts. There was a trend towards concordance of drusen characteristics be tween siblings but not between spouses, although the difference achiev ed 5% significance only for the number and density of drusen in the ce ntral macula. The difference of concordance between the probands and s pouses and the probands and siblings was significant for all character istics. These findings support the belief that genetic factors influen ce age-related changes in Bruch's membrane. They also imply that envir onmental factors are less important or alternatively that the environm ental variation between households included in our study was not great enough to be evident.