Sorry Marvin, I didn't see this post until I answered the other one we had going before.
I would still advise Eve to see a mental health counselor. She is going through a very stressful and potentially devastating trauma now and needs all the support she can get. A counselor can help her learn how to manage all she is feeling now and help her find ways to cope with her fear most of all.
I hope when Eve told her sisters they were supportive. It will go far for Eve to have her family's (and your family's) support as well. Anyone reacting negatively to the news (not supportive or saying something unhelpful) can have an affect on Eve.
Looking for wedding rings is a wonderful boost to Eve, I'm sure! But she may also have mixed emotions because for how happy she feels about marrying you, she is also fearful of being a burden should she go blind. Helping her cope with her fears through consistent reassurance will help her find more joy in your happy future.