Kitten's actual eye black?

[Locusta]

This might sound strange, but this ios my first cat, so I thought I should ask.

I recently rescued a 4-week old kitten off the streets, and when we pulled him out of the rain gutter his eye was crusted shut. I took him to the ER and they gave me eye ointment and antibiotics.

I was supposed to put the eye ointment in for 7 days, but as the infection was persistent, I continued the treatment for a few more days. Today, his first day without the ointment, his eye is almost 100% open, and I can no longer see his inner eyelid. However, now that I can see the entirety of his eye, it looks like there is a black ring around his actual eye that is not present in the other eye. It also seems to be a muddier color.

Is my cat's eyes just changing colors? Or should I be concerned?

I can't really afford a Veterinarian right now-he can't be insured until he is 6 weeks old, either.

I'd really appreciate the help! Thank you.