Animal Models of Cataracts

Cataract is an opacification of the lens that results in obstruction of light and gradual loss of vision. It continues to be the leading cause of blindness worldwide despite the availability of effective surgery in developed countries. Primary cataract surgery is the most frequently performed surgical procedure in the world and remains the only cure. However, the surgical intervention is not without problems and can lead to a number of complications, the most common of which is secondary cataract, also known as posterior capsular opacification (PCO). The underlying causes of cataract are quite diverse with the majority acquired after middle age and referred to as “age related.” Congenital or juvenile cataracts, considered as “early-onset” cataracts, are less common but nonetheless have significant visual consequences. A number of risk factors have been identified that are associated with age-related cataracts, including diabetes, sunlight (ultraviolet light) exposure, smoking, steroid use, and oxygen exposure. Although studies in humans have provided important clues toward the potential causes of cataracts, elucidation of the mechanisms underlying cataractogenesis has only been possible through the use of experimental animal models. These models range from small animals such as mice, rats, chicks, and guinea pigs to larger mammals including rabbits, dogs, and primates. The goal of this chapter is to describe the experimental animal models most commonly utilized for investigating the genetic and environmental risk factors known to contribute to cataract formation. The strengths and weaknesses of each of these models are highlighted, as well as any recent advances.