Chihuahua puppies first open their eyes 10 to 16 days after they are born. Their eyes are sealed from the time they are born until this happens.
All puppies are born blind and deaf. They are able to smell, and they use this sense to locate their mother even though they cannot see her. The milk in the mother's breasts has a scent the puppies are able to follow.
Some puppies are born with cataracts, although these can improve with age. As the puppy grows, the lens grows as well, but the cloudy area that makes up the cataract does not increase in size. When the puppy reaches adulthood, the cloudy area is proportionally small compared to the rest of the lens. The adult dog is able to see around the cataract.