POSTERIOR AMORPHOUS CORNEAL-DYSTROPHY - A NEW PEDIGREE WITH PHENOTYPIC VARIATION

Background: Posterior amorphous corneal dystrophy is a rare condition characterized by bilateral sheet-like opacification of the posterior s troma in association with corneal flattening and thinning. It has been reported in only four families, all from the Unites States. The autho rs report on a fifth family, the first from Britain, with nine affecte d individuals. Methods: Slit-lamp photography, refraction, keratometry , pachometry, corneal topography, and specular microscopy were used to assess the family members. Results: Two distinct forms of the disease were identified. All patients with the centroperipheral form were hyp ermetropic and had keratometry readings below 41.00 diopters and a cen tral corneal thicknesses less than 0.50 mm. Those with the less severe peripheral form were less hypermetropic, some slightly myopic. and ha d keratometry readings above 41.00 diopters, but the central corneal t hicknesses was similar to those with the centroperipheral form. No abn ormalities of the endothelium were detected, and visual acuity was onl y mildly affected. The condition appears to be nonprogressive. Conclus ion: Though the centroperipheral form of posterior amorphous corneal d ystrophy is more likely to lead to presentation, most patients are asy mptomatic. This dystrophy can be very subtle in its appearance and eas ily overlooked. This led the authors to suspect that the prevalence of this condition is higher than the few reports in the ophthalmic liter ature suggest.