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 stroma in association with corneal flattening and thinning. It has been reported in only four families, all from the United States. The authors report on a fifth family, the first from Britain, with nine affected 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 hypermetropic and had keratometry readings below 41.00 diopters and a central corneal thicknesses less than 0.50 mm. Those with the less severe peripheral form were less hypermetropic, some slightly myopic, and had keratometry readings above 41.00 diopters, but the central corneal thicknesses was similar to those with the centroperipheral form. No abnormalities of the endothelium were detected, and visual acuity was only mildly affected. The condition appears to be nonprogressive.

CONCLUSION

Though the centroperipheral form of posterior amorphous corneal dystrophy is more likely to lead to presentation, most patients are asymptomatic. This dystrophy can be very subtle in its appearance and easily overlooked. This led the authors to suspect that the prevalence of this condition is higher than the few reports in the ophthalmic literature suggest.