Poor eyesight just might be an advantage. If you can’t see well enough to focus on details such as the attacker’s face or hand, you will inevitably see him as a whole, primarily his motion and direction.
When you relax the muscles around the eyes and let yourself use your peripheral vision you become aware of what is happening around you. The ability to not over focus, not concentrating on one particular limb/person, is priceless in a martial situation as you interact with multiple attackers.
