The cornea is the outer layer of the eye and has clarity and strength. Its clarity important for vision. The cornea is a transparent avascular connective tissue. The human cornea consists of 5 layers; 3 cellular (epithelium, stroma and endothelium) and 2 interfaces (Bowman's membrane and Descemet's membrane). Corneal opacification is a medical condition that affects the light transmission through the cornea. Corneal opacification may be unilateral or bilateral, in the form of corneal clouding, central, peripheral or diffuse opacity. Corneal opacities may occur in an isolated form or in association with various syndromes and diseases. Corneal opacification may include Congenital Corneal Opacification, Cornea Plana, superficial, stromal and posterior Corneal Dystrophies, keratoendotheliitis fugax hereditaria and Keratoconus. Several genes are implicated in corneal opacification. They may be genetically determined and may show genetic heterogeneity. They may have an autosomal dominant, an autosomal recessive or X-linked inheritance. This review will discuss different gene involvement with corneal opacities.