Vision is one of the five human senses. It is responsible for approximately 90% of the information that reaches the brain from the environment. Sight is so valued among the Americans that blindness is feared second only to cancer, according to some surveys. This demonstrates the importance we give vision and the catastrophic effect of blindness on our social, economic and personal life, and this is the reason that it must be preserved and maintained healthy.  Ophthalmology has considerably developed in recent years and there are now safe and effective means of restoring vision and preventing its deterioration.