However, there is another disease in Goldens known as pigmentary uveitis or "Golden Retriever Uveitis" which is known to lead to glaucoma, and can be very painful to the dog along the way. When dx'd early enough certain meds will slow down or stop the progression of the disease. I've been told that these meds don't work on all dogs, though. I do know of dogs who have had to have the affected eye removed as the only recourse. Have not heard of cataracts being painful, but the glaucoma is. This is all pertaining to Goldens, not Labs.
A good friend has a Golden blind from prcd-PRA. The dog is 12-1/2 now, though blind, she is happy and healthy. She does not have much cataract formation, and if you met her you might even have a hard time telling she was totally blind. She still retrieves bumpers in the yard ... waiting to hear them hit the ground and then running to the area and using her nose to find them!