The human brain's ability to compensate for things like this is amazing. I once knew a girl who had Nystagmus, which is a condition where the eyes involuntarily move side-to-side or up-and-down repeatedly and rapidly. She functioned relatively normally, could read, drive a car and watch movies/TV rather well. Before I knew what her condition was, I found it difficult to talk to her face to face because I would focus on her eye movements and it made me feel rude so I would try to avoid eye contact. After finding out what Nystagmus was, the whole concept of her having relatively normal vision was mind boggling. I later learned that she didn't see the world shaking constantly since her brain was filtering out the motion and piecing together the semblance of a steady image. She couldn't see rapid movement well and had moderately impaired depth perception, but that didn't seem to get in her way much. The brain is truly amazing for being able to process the world even when the information it receives is corrupted and distorted.