A cataract is an opacity of the lens within the eye. The function of the lends is to focus light on the retina. Therefore, cataracts decrease vision by interfering with light reaching the retina.
Cataracts are a leading cause of visual impairment in dogs. Vision of affected dogs can often be restored to a normal state by surgically removing the abnormal lens (cataract) and substituting an artificial lens in its place.
Currently the only effective treatment for cataracts in through surgical removal of the affected lens. Cataract surgery is a preformed under general anesthesia by the use of phacoemulsification, which uses ultrasonic waves to breakup the cataract. The cataracts fragments are then moved using irrigation/aspiration. In most cases an artificial intraocular lens is then implanted. After the healing process is complete, vision is typically restored.