Check out the Cleveland Clinic's website on this issue. They say that macular edema is rare with Gilenya, but it is a known possible effect. Since you will be checked and tested as time passes, this shouldn't be a major problem, but if it worries you then you may want to reconsider participating in the study.
Good health to you.
ess
I have been on Gilenya for 2 months now. Before starting you must see an eye doctor and get checked for macular adema. I was all clear so I was able to start the drug. I will see the doctor again next month for my 3 month check up. It seems that if macular adema is going to occur, it will happen in the first few months. Both my eye doctor and neuro explained to me that if it does appear, I will be taken off the Gilenya and the eyes go back to normal. I am hoping for a good report!
Good luck,
Deb