Hello everyone and everybun,
I know I don’t come on here often enough, but I wondered if I could pose a question to those with dogs. Especially any who have had sight problems.
I have a soon to be 8 year old Yorkie/Chihuahua cross (that’s her in my avatar) that has just been diagnosed as functionally blind. Her symptoms are pupils that don’t contract properly and some greying to her lenses that the vet who saw her (a new one as we’ve just moved so no one with history with her) felt that her retinas must already be gone. There are two possibilities as to the cause: glaucoma or something called progressive retinal atrophy. Neither can be cured, only managed, but the approach to each is vastly different as with glaucoma dogs sometimes need their eyes removed. 
The thing is, having lived for all her life in Alaska, (as well as my other animals-cats and rabbits), I wonder if it might be something else having to do with her environment, because in all honesty I don’t see any of my pets except for our youngest dog and cat showing proper pupil contraction, and even they are a little on the slow side. In other words, all my pets have some degree of dysfunction of their pupils.
Has anyone ever heard of anything like this, particularly in rabbits as I want to keep this relevant to the forum at large? I notice none of my bunnies have pupils that contract very well in bright light. I’m thinking it’s a learned behaviour from living in a place that is mostly dark for six months of the year. In the interest of full disclosure, one bunny has been blind for some time, so I don’t expect his pupils to react rightly, but the other two should, one would hope.
I’m really worried about my dog though because while I figure she is losing some depth perception, I’d like to find some way to slow the progression of whatever is wrong with her eyes so that she isn’t completely sightless before she reaches old age.
Many thanks in advance for any and all replies. 