Cataracts are the clouding of the lens inside the eye which affects the horse's vision, blocking images as opposed to light. Cataracts can be developmental (including congenital forms), or acquired secondary in horses. Developmental cataracts are the most common form of cataracts affecting horses, and most are congenital. The severity depends on the location and extent of the lens opacity. If the entire lens is affected, it causes blindness.
Cataracts are classified according to the stage of development (incipient, immature, mature or hypermature), location (anterior, posterior, perinuclear, nuclear or equatorial, capsular, subcapsular or cortical), age of onset (congenital, juvenile, senile) and cause (traumatic, inflammatory, hereditary).
Treatment Options for Horses with Cataracts
Not all cataracts may require treatment. For those that do, cataracts can be surgically removed through a procedure known as phacoemulsification. It involves the surgeon using a special probe that vibrates at ultrasonic frequencies to liquefy and break apart the cataract followed by vacuuming it out of the eye. This procedure has had good short-term success for horses with cataracts, however it has not been as favorable for long-term success.