I have noticed lately that Boots, my 17 yr.old neutered Maine coon tomcat, has, as the article mentioned, "a round large pupil almost filling the whole iris area" , both at night and during the day. Should I be concerned about possible blindness?? It will kill me if so, because my other cat (who's since passed on) developed glaucoma. Boots has never been outdoors in his life, and he has suddenly gotten very vocal. My vet said the other cat went blind because, for one reason, he was out in the sun all day. Any help would be appreciated. The picture is of Boots taken 5 yrs. ago, in 2005.