Macular corneal dystrophy in Iceland.

This study includes the fourteen Icelanders who had penetrating keratoplasty for macular corneal dystrophy during 1974 through 1988, and a further five patients whose deterioration of vision has so far not led to surgery. The clinical presentation, mode of inheritance and the course of the disease were similar to those seen in other studies. The genealogical part of this study indicates that the gene responsible for the disease was already present in Iceland in the 18th century. Though consanguinity, as usually defined, was found to be uncommon, the relatively small pool of genes in the Icelandic population which numbers at present about 250,000 has led to higher prevalence of macular corneal dystrophy than elsewhere. The histopathological findings concur with the conventional description of macular corneal dystrophy, with the exception of two patients with unusually severe photophobia. In these two cases, electron microscopy revealed that the most anteriorly situated deposits were sometimes associated with increased electron-density of small clusters of basal epithelial cells in the overlying epithelium, such cells also being reduced in size and exhibiting few organelles other than swollen mitochondria.