Cats with hearing or vision loss can adapt well, especially if the loss occurred when the cat was young. However, you should never let a deaf or blind cat outside -- he is at a serious disadvantage when not in the familiar environment of your home. Visitors and others in your household should be aware of your cat's condition. Avoid making loud noises around a blind cat or sneaking up on a deaf cat.
Blind cats can figure out the layout of their home by touch. You may want to keep your cat restricted to certain rooms or levels of the house to keep him from falling down stairs or accidentally getting outside. Once a blind cat learns the lay of the land at home, try not to change anything. Keep food and litter boxes in the same place. A blind cat relies on landmarks that are at cat level -- just a few inches off the floor -- so even something as simple as leaving shoes in the hallway can throw him off. Blind cats love toys that make noise due to their heightened sense of hearing.
Deaf cats process the world through their sense of sight and touch, and they feel sound as vibrations. You may not be able to get your cat's attention by calling his name, but you can stamp your foot or knock against a surface. Keep in mind that the thuds and crashes that would send a hearing cat running for cover are lost on a deaf cat. Try to provide your cat with safe forms of visual stimulation and remove anything dangerous such as breakable knickknacks.
It can be more challenging for both the owner and the cat if the animal becomes blind or deaf later in life. Your cat's senses and body functions also slow down as he ages, and hearing and vision are no exceptions. Once a cat passes middle age (anywhere from six to ten years old), expect him to lose a little edge. The difference with an elderly cat whose vision or hearing has gone down is that his other faculties have diminished, too. It's more difficult to adapt when you have a lifetime habit of relying on fully-functioning eyes and ears.
The most important ingredient is patience -- your cat is doing the best he can. With your caring and sensitivity, your blind or deaf cat can live a full and happy life.