Hello, my name is***** and I have over 20 years of experience as a veterinarian. I'm sorry to hear that your fellow's eye does not seem to be improving even with the recommended treatment, I understand that must be frustrating.
My concern is that he has more than a simple corneal scratch, but rather has another problem that is precluding him from healing.
One possible underlying problem is KCS or dry eye. This is an autoimmune like condition in which the body attacks the tear glands and scarring results with decreased tear production. This can be very uncomfortable for them. With poor tear production the eyes don't get dirt and bacteria flushed out as it should be, his eyes will be itchier and he will rub them more, thus predisposing toward infections and possible ulcers/scratches.
KCS is diagnosed by measuring tear production with a special test called a Schirmer tear test, which measures the amount of liquid tears in the eyes at the time they are tested. Sometimes if a dog is stressed or excited we get normal levels, when most to the time they are not. So with a normal test level if I have a strong suspicion that tear production is poor I will ask to retest them at a later date.
Ideally once we resolve the current ulcer we would use an immunosuppressive eye drop to knock down his immune system's reaction and allow his tear glands to start functioning again. Common immunosuppressive medications include Tacrolimus or Cyclosporine eye drops. These drops or the oil vehicle that they are in can be very irritating, especially when his eyes are already so sensitive. We often need to start with medication at a lower percentage concentration level to acclimate the eyes and then increase the percentage in the product.
Unfortunately the other problem is that these drops can take several weeks to start working. If you stop too soon then he won't respond.
In the meantime while we get his ulcer to heal I often will recommend using artificial tears too to keep their eyes more comfortable. You can use any artificial tear product while waiting for his eye to heal, but the drops rather then the gel formulations seem to be a little more soothing. In many cases we use artificial tears during the initial adjustment period while waiting for immunosuppressive drugs to start working as well.
You can use artificial tears now to soothe his eyes until he can see his veterinarian, except for the 24 hours before her appointment when they need to measure his levels of tear production.
Another possible cause of repeated infections are allergies, which make his face very itchy, and when he rubs her face he accidentally introduces bacteria into his eyes.
These dogs benefit from artificial tears too.
Dogs with very large, prominent eyes like Boston Terriers often have dry eyes because their eyelids can't cover their eyes fully and spread tears properly. They are more predisposed to injuries too.
These breeds, because of their conformation, are also prone to indolent, non healing ulcers. These may require surgery to heal their original ulcer and follow up care with drops to keep their eyes healthy long term.
Ideally you would start with a recheck veterinary visit to measure tear production and restain his ulcer/scratch.
In the meantime it is fine to use artificial tears as often as possible.
Best of luck with your fellow, please let me know if you have any further questions.