Megalocornea, or anterior megalophthalmus, is a bilateral inherited developmental anomaly found almost entirely in males, in which the intraocular tension is not above normal, the corrected visual acuity is normal, and the anterior segment of the eye is larger than normal.* It is usually inherited as a sex-linked recessive trait, but may occasionally be due to an incompletely dominant gene.4
The differentiation of megalocornea and buphthalmos or hydrophthalmos is not difficult if one is aware of this rare condition. In megalocornea both corneas are enlarged, with horizontal diameters of from 13 to 18 mm., and the intraocular tension and corrected visual acuity are normal. In buphthalmos and hydrophthalmos the corneas are also enlarged (35% unilaterally), the intraocular tension is above normal until treated, and the corrected visual acuity is often not normal.
Kestenbaum's5 table differentiating megalocornea and buphthalmos is translated in Duke-Elder's "Text-Book"2 and in Vail's widely
SMILLIE JW. Cataract Surgery in MegalocorneaReport of Case of Two Extractions and Review of Cases Since 1931. AMA Arch Ophthalmol. 1955;54(2):217-220. doi:10.1001/archopht.1955.00930020223008