Fuchs' endothelial dystrophy: a fresh look at an aging disease

The increasing number or corneal and intraocular surgeries performed togeth er with longer life expectancy, elevates the risk for developing symptomati c Fuchs' endothelial dystrophy (FED). This article reviews the current unde rstanding of FED, and, in addition, a case of early FED is presented clinic ally and histopathologically. Two FED corneas from one patient were examine d histopathologically using an established histological protocol for light and electron microscopy, FED is an inherited autosomal dominant corneal end othelial disorder with incomplete penetrance that is up to 3 times less lik ely to develop in men. Treatment options are primarily palliative while sur gical intervention routinely involves a penetrating keratoplasty. In this d isease process the endothelium produces excessive amounts of basement membr ane material of an abnormal composition resulting in the formation of a pos terior collagenous layer. Extreme accumulations of this material created mu shroom-like formations, guttae, projecting into the anterior chamber. The e ndothelial cells were extremely thinned over the guttae, to the point where the cells may provide little more than barrier function. Despite a presuma bly compromised endothelial pump the corneas appeared relatively free of ed ema clinically and histopathologically, However, some edematous pockets dee p in the basal epithelial layer were present suggesting that epithelial inv olvement occurs at an early stage in the disease. An early diagnosis of FED will help patients and surgeons to better elect optimal surgical timing an d procedures. The current trend is to intervene surgically before the patie nt reaches the painful end-stage. Interestingly, in the case examined, the endothelium presumably provided only a barrier function over large areas wi th an apparently reduced contribution from the endothelial fluid pump and y et the corneas remained relatively clear. Future research may confirm that decompensation occurs only when complete endothelial coverage is lost. If t he endothelial barrier function is more important to corneal transparency t han the endothelial pump function in FED, then the relative combination of these two functions in the normal cornea should also be reassessed. (C) 199 9 The College of Optometrists. Published by Elsevier Science Ltd. Ali right s reserved.