Hello, Delores and welcome!
I'm sorry to hear that Joey's hair loss on his back, has you worried. Sometimes, older cats will experience hair loss or thinning of the hair for a variety of reasons. If you're sure he has no fleas or other external parasites, he might be experiencing allergies to his food. Even if he's been eating the same for a long time, if it includes any common allergens like corn, soy, wheat, gluten, dairy products, carageenan, artificial preservatives, flavors and/or colors, these can cause an allergic reaction resulting in hair loss.
Even if you see no fleas, he could have had 1 flea bit him and an allergic reaction to flea saliva can ensue, long after the flea is gone. Older cats are also more prone to develop medical conditions like diabetes, hyperthyroidism, liver and kidney issues, and these can adversely affect the coat, especially hyperthyroidism. Here is more information:
Ringworm, a fungal skin infection, very often causes hair loss; sometimes it is itchy and sometimes, not. Here is more information:
If Joey rubs excessively on certain places in the house, or if he spends time outside and is in contact with various flowers, plants, grasses, etc., this could be another possibility. Here is additional information regarding hair loss and other problems in older cats:
It would be advisable to have him evaluated in person by a vet as soon as possible, and some skin scrapings (painless) may be taken to do a culture. The vet can also use a special light called a Woods Lamp, to see if there are ringworm spores present.
If his fur is dry, you can run a humidifier in the rooms where he spends the most time.
I hope all will be well with Joey and please let me know what the vet tells you, after the visit and any tests. Thanks!