When the legal blood-alcohol level is reached and surpassed, depth perception and night vision are affected. It becomes impossible to accurately judge how far away objects are when depth perception deteriorates. Vision becomes blurred or you may see double since eye muscles lose their precision causing them to be unable to focus on the same object.
Alcohol affects night vision by keeping the pupils from adapting from darkness to light .
The oncoming headlights of a car will cause a drunk driver to be dazzled much more severely than a sober driver. During the daytime, under normal driving conditions, reduction in contrast sensitivity might not cause any problems. In more unfavorable conditions, such as fog or at night, alcohol can reduce the visibility of an object to the point of being below the threshold of detectability. These goggles give the wearer a blurred and distorted impression of the world around them. Most patients with tobacco-alcohol amblyopia suffer from severe nutritional depletion, and visual improvement in these patients seems to be related to improved nutrition rather than to abstinence from alcohol.