Hi!
Sorry about your hen being ill.
Comb turning blue is a sign of a respiratory problem. The Clavamox hopefully is taking care of that.
Gapeworm is very rare. You said she had no open mouth, no gasping, no other symptoms other than swollen/red eyes. It might be part of her respiratory infection, if she has one, or a sinus infection. Both could also be something the Clavamox will help. I'm not sure what the Ivermectin was for, but I wouldn't give her a wormer right now while she's on these.
Be sure to finish the Clavamox prescription, then give her probiotics for a couple of weeks. That can be powdered that's put in water, or small amts of sugar free yogurt, or fermented feed/grains if you happen to be doing that.
As for finding out if she's blind, maybe wait until she's off these drugs your vet has her on before evaluating further for if she's got vision problems.
Hopefully, what the vet put her on will show improvements in her very soon! Keep us updated on her progress.