Our middle cat had a vaccination reaction... but there was was no permanent
damage.

Vaccines in general for pets are poorly regulated, and I suggest to you to consider NONE of them, except the distemper, and rabies.

When we get the rabies now, the vet premedicates with Benadryl injection
10 minutes before, for Tippy. Her reaction was when a mixture was given, and since several were given that day we don't know if it was the rabies or the others. Oreo got very down, sickly when she had her kitten shots...the distemper, etc. But not a reaction per se.

The most common side effect of vaccines in cats is vaccination sarcoma (cancer).
Tippy was the first cat we ever had to have a reaction. She too was in the vets overnight.

It is possible this cat has some inherited issue, as well. Some of our vets here use nasal vaccines. Was that done on poor Moonshadow? Is he the smaller one? Nasal could go right to the brain!

There is a very interesting website called:
www.thecatsite.com

There may be others there to help you out. Such as whether the blindness continues or is temporary. There are vets there sometimes to field questions.

So after carefully reading this thread, was it the vaccine or the Ketamine?
Could he have had a mild encephalopathy all along, and that is why he is smaller? On this site blindness is discussed:
http://www.vetinfo.com/canesthesia.html

I don't neuter/spay when my pets are very young. The Humane society does and I have seen kittens die as a result (friends). I only neuter/spay when they are bigger/older and stronger.

This is so tragic.