Loss or reduction in corneal transparency occurs from a variety of causes, including edema resulting from diseases such as Fuchs’ dystrophy and bullous keratopathy, scarring resulting from wound healing, haze following photorefractive keratectomy, and certain metabolic diseases such as corneal macular dystrophy. The intent of this chapter is to review the present understanding of mechanisms or structural alterations that cause loss of corneal transparency. Transparency loss resulting from edema, scarring, and photorefractive keratectomy will be emphasized.

Understanding the mechanisms of transparency loss requires understanding the structural bases of corneal transparency itself. Because the cornea does not absorb light in the visible portion of the electromagnetic spectrum, its transparency is the result of minimal light scattering.^[1,2]Visible light is an electromagnetic wave with wavelengths between 400 and …