Contributor: Gordon K. Klintworth
High myopia is myopia of >6.5 diopters. Both genetic and environment factors play seem to contribute to this extreme form of myopia, which affects 1-2% of the general population. High myopia may be inherited as an autosomal dominant, autoomal recessive or as a X-linked recessive trait. Nonsyndromic autosomal dominant high myopia has been mapped to 5 loci [MYP2, MYP3, MYP4, MYP5, MYP11] and high myopia has one locus on the X-chromosome [MYP1]. Causes of high myopia include Knobloch syndrome and Åland Island eye disease. Thinning of the sclera accompanies high myopia, particularly at the posterior pole of the eye. Persons with high myopia are at increased risk for several serious complication that impair vision: retinal detachment, macular degeneration [myopic chorioretinal degeneration], cataract, and glaucoma.