Age-related changes and diseases of the ocular surface and cornea.

Aging of the ocular surface and corneal tissues, major components of the visual system, causes major eye disease and results in substantial cost in medical and social terms. These diseases include the highly prevalent dry eye disease that affects the ocular surface and its glands, leading to tear film alterations, discomfort, and decreased vision. Studies show that 14.4% of the population in the United States older than 50 years have dry eye disease and demonstrate that it is particularly prevalent among women. Annual medical costs per patient with dry eye in the United States are estimated at $783 per year, with an overall medical cost adjusted to prevalence of $3.84 billion per year. Societal costs, which include loss of productivity, are estimated per patient at $11,302 per year, with overall costs adjusted to prevalence of $55.4 billion per year. Because there are few effective treatments for the disease, more research on its etiology and mechanisms is warranted and needed. Increased public education about risk factors for the disease is also required. Another major age-related eye disease of the cornea that leads to vision impairment and potentially blindness if left untreated is Fuchs' endothelial corneal dystrophy. This disease leads to loss of the endothelial cells on the internal side of the cornea that are responsible for keeping the cornea in the proper hydration state to ensure its transparency to light. The mechanism of cell loss is unknown, and the only treatment available to date is surgical transplantation of the cornea or inner part of the cornea. These medically costly procedures require donor corneas, eye banking, and medical follow-up, with accrued costs. Fuchs' endothelial corneal dystrophy is a major cause of corneal transplantation in the United States; therefore, research support is needed to determine the mechanism of this age-related disease, to develop medical, nonsurgical methods for treatment.