That's a pretty vague question. I think it would be very reasonable to get a complete eye exam with an ophthalmologist to find out. It would be very easy to see if you needed glasses. Also your medication list can be gone over to see if any of them could be related.
I would recommend that you seek the care of an eyeMD to determine the cause of your squinting. It is possible that you light sensitive due to a need for glasses, a lazy eye, inflammation inside the eye, dryness and a host of other causes.
Sandy T. Feldman, M.D., M.S.
ClearView Eye and Laser Medical Center
San Diego, California