An electroretinogram is used to help diagnose several different disease that can cause blindness in your pet, such as progressive retinal atrophy (PRA), sudden acquired retinal degeneration (SARDs), or blindness secondary to disease of the central nervous system. It measures the function of the retina and determines if an electrical signal is being sent to the brain. It is similar to an EKG or ECG of the heart, where Dr. Low can see an electrical signal on her monitoring screen. This procedure is performed before every cataract surgery to make sure your pet is a good candidate for surgery. Typically, the procedure is done with your pet awake. The procedure is non-painful and lasts about 45 minutes.