I don't have a cat but I do have a dog with blue eyes. They are definitely hard to photograph, his always turn out red. I find if the lighting is really good (either outside or I position a lamp near him plus the regular lights) his eyes come out looking natural instead of red. Plus turning off the flash will help but if the lighting is bad it will be hard to get your pictures focused and not blurry. When I take closeups of Nebo's eyes I turn it on closeup mode which by default turns off the flash.