There are thousands of genetic disorders known in humans and approximately a third of them affect the eye.¹ Furthermore, of the cases of blindness caused by disease, 75% occur in individuals under 15 years of age and approximately 50% of these are hereditary. Genetic factors are involved in several of the most important diseases to affect the anterior segment of the eye, i.e. the cornea, anterior chamber, iris, ciliary body and lens. These include developmental disorders such as anophthalmia, microphthalmia, aniridia and coloboma, pigment disorders including heterochromia and ocular albinism, the corneal dystrophies, congenital and age-related cataract and the various forms of glaucoma. Many of these disorders are associated with multiple genes and they can occur either as an isolated eye problem or as part of a more complex syndrome.

Advances in gene technology have significantly increased the number of gene locations and specific genes associated with anterior eye disease, thus greatly increasing the possibility of genetic testing.² These advances have had a considerable impact on the classification and diagnosis of anterior eye disease and will increasingly determine their management and treatment options. Hence, genetic advances have resulted in clinical trials of gene therapy in disorders elsewhere in the eye, such as Leber’s hereditary optic neuropathy, retinitis pigmentosa, X-linked retinoschisis and Stargardt’s disease^3,4 and many more such trials are likely in the future. This article provides a current perspective of the genetics of anterior eye disease and describes: (1) the genes associated with each disorder; (2) how the presence of abnormal genes may cause disease; and (3) the advantages and disadvantages of genetic testing. This article aligns with GOC competency 6.1.4, i.e. it identifies external pathology and offers advice to patients not requiring referral.