Snow should not cause that kind of problem (after all its just water). Unless it had chemical impurities in it or was thrown into the eye with force. So your situation is not at all typical. You should be on the phone calling the ophthalmologist you saw and asking those questions. Now way I can answer it, it must have been rather severe to prescribe a steroid
I'm not a doctor, but I know from cold hard experience that sufficient damage to the eye can cause this for weeks. I had light sensitivity and pain for a couple of weeks before I finally went to an ophthalmologist (because my *optometrist* said everything was OK - moral of that story - don't go see an optometrist for damaged eyes, go see a medical doctor, but that is another story). Do what Dr. Hagan said - get on the phone to your ophthalmologist now.
My eye was blurry for quite a while, but it eventually healed.