According to WebMD, certain diseases alter the clarity of a cat's eye, making it cloudy or seem like a blind eye. Loss of transparency or clarity of the eyes indicates inner eye disorders. If the cat's eye has lost clarity or transparency, but is not painful, cataracts are the most probable reason. If the change is accompanied by pain, glaucoma, keratitis or uveitis might be the underlying cause.
If the color of an eye changes, it might be an indication of a cancer known as melanoma. Making sure the cat has thorough check-ups and all the necessary vaccinations is the best method for preventing eye disorders. Wiping any crusty gunk from the eyes with a damp cotton ball will also go long way in preventive care.
WebMD states that the cloudiness in the cat's eye can vary from complete opacity to a slight, localized haziness. The cat's eyes gain a uniform blue-gray appearance in case of corneal edema, in which fluid builds up, in the usually clear cornea. Complete opaqueness of a cat's eye might be misread as blindness, but this could be an indication of another serious medical issue. In case of cloudy eyes, seek immediate professional attention, especially if the cat shows signs of pain. Eye problems can escalate quickly.