My 15 year old terrier mix has corneal dystrophy and has cataracts removed from both eyes. His right eye has what the ophthalmogist vet calls "gritty lipids", which work their way out of the eye and feel very uncomfortable, like a grain of sand in the eye. When one is working out of the eye, my dog squints and his eye tears more. I can tell he doesn't feel well.The veterinary ophthalmologist he sees has prescribed Edetate Disodium 1% ophthamlic solution, EDTA, one drop in affected eye three times a day. My dog has also been prone to corneal ulcers.The EDTA has really helped. He also gets Optixcare eye lube plus with hyaluron. That you can get over the counter from Amazon. He gets one drop three times of day of Optixcare which makes his eye feel better.
If you can, finances and location, get a referral for a vet ophthamogist. We have been seeing one for four years since my dog developed diabetes, diabetic cataracts and corneal dystrophy. He's still going strong four years later. His vision is not so good in the bad eye, but he can still see some. Good luck with your dog.