This eye test is really very simple. The drops that they use dilate the pupils in order to inspect the eye, so everything is silly bright when you go outside. Bring sunglasses and take a cab, it's really not a complicated test at all, and actually not a bad idea even if it isn't required in order to ensure a healthy eye.
It's not impossible to drive after, it's just like going out on a really bright day without sunglasses. It hurts the eyes a bit, so i'd just as soon have someone pick me up than struggle to drive myself.