Abstract
Abstract: :
Purpose: To assess the ocular characteristics of hereditary megalocornea to assist with its clinical differentiation from infantile glaucoma. Methods: Four unrelated male patients with hereditary megalocornea aged 3 months to 8 years were examined ophthalmologically including gonioscopy (3 patients), iris transillumination, iris contour evaluation, tonometry, fundoscopy and ultrasound assessment. Results: All patients possessed abnormally enlarged corneas, very deep anterior chambers and backward bowing of the irides. Peripheral iris transillumination defects were present in 3 of 4 children, all over 5 years of age. Tonometry found normal eye pressures in all patients. Gonioscopy found abnormal pigment in the trabecular meshwork in 3 of 3 patients examined who were between 3 and 8 years of age. Pigmentation was absent in 2 children under 2 years, but was later acquired by one of the children when seen for reexamination at 5 years of age. No optic nerve abnormalities were present. Ultrasonography documented normal globe size in each patient. A difference in corneal diameter was seen in 3 of 4 children. Conclusions: Hereditary megalocornea is a rare clinical entity easily confused with infantile glaucoma because of enlarged corneas in each condition. Affected children with megalocornea demonstrate unique associated anterior segment abnormalities not seen in infantile glaucoma. These defining clinical characteristics include enlarged corneas without breaks in Descemet's membrane, very deep anterior chambers, backward bowing of irides, transillumination defects of the irides and heavy pigmentation of the trabecular meshwork after 3 years of age, normal eye size and normal eye pressures. Asymmetric corneal diameters are common in infantile and hereditary megalocornea.
Keywords: anterior segment • cornea: basic science