Good evening :) I'm Dr. Sara - I'm a licensed veterinarian who works exclusively with cats and dogs. Thanks for sending in your question, and I'm sorry that your Boy isn't feeling so well!
Runny noses and eyes most commonly signal a chronic viral infection with the feline herpes virus. Certainly there can be many other causes, but herpesvirus would be the one that I see most often. Cats are infected with herpesvirus when they are young and it stays in latency within their nerves, coming out of latency occasionally to cause mild upper respiratory symptoms like sneezing, and watery nasal and eye discharge. As our kitties age, their immune function can begin to decline and we see more frequent or more severe breaks with the herpesviral symptoms. L-lysine is an amino acid that can be used to lessen the severity of signs caused by herpesviral infections. It is formulated in multiple different cat friendly ways - treats, powders, and gels most frequently, and can be purchased from your vet, at the pet store, or online.
At his age, though, it's a good idea to have him looked over by your vet to make sure my interpretation of your description is appropriate. It's certainly possible that he may have a secondary bacterial infection now that would require antibiotics, or that he has developed something else off the wall that wouldn't be obvious without being able to perform a physical exam on him. It may be more than just age causing him to be more susceptible to upper respiratory signs - sometimes if they are ill from other chronic diseases like diabetes, kidney disease, thyroid disease, or cancer, this can also manifest as a general decline in condition and vague symptoms like you're seeing.
Please let me know if I can answer any other questions for you:)