Vision

[rgrcpa]

I have a question that has troubled me for some time. When I go to my eye doctor for a routine eye exam, he always dilates my eyes. I understand that this deadening of the eyes makes it easier for the doctor to see things in the back of the eye that he wouldn't see without the dilating. HOWEVER, why then does he immediately begin fitting lenses in the big eye machine so he can write an eyeglass prescription? I don't go about with deadened eyes when I drive, watch tv, or read. Why dilate to prescribe eyeglasses? Can anyone explain this? Seems to me that the prescribed glasses would be off.
The exam environment is different than my routine life.

Rick Roberts