Epigenetic mechanisms might help explain environmental contributions to the pathogenesis of keratoconus.

The etiology of keratoconus (KC) seems to involve genetic and/or environmental factors such as rubbing and/or contact lens trauma and/or exposure to ultraviolet radiation. An examination of the possibility that epigenetic mechanisms could contribute to the tissue changes in KC has been considered in this review. The tissue changes in KC result in thinning and/or other forms of mechanical weakening of the cornea, which cause it to become more susceptible to the distending forces of intraocular pressure with associated development of a cone. Rather than being caused by a single gene mutation, a complex or multifactorial disease such as KC involves multiple genes plus lifestyle and environmental factors. The epigenome of a cell is highly dynamic, being governed by a complex interplay of genetic and environmental factors. The full range of epigenetic marks is currently unknown but is potentially enormous. Although further elucidation of the genetic determinants of KC is important, there is now increasing interest in exploring how non-genetic variants, such as epigenetic factors, could influence complex disease etiology. Studies of epigenetic processes in KC may help explain the relationship between the genome and the environment and provide new clues for modifying these processes with the possibility of preventing the development of KC or stabilizing its progress. Epigenetic linking may be relevant to other complex ocular diseases that involve environmental factors including those that involve exposure to ultraviolet radiation.