The eye is an optical system, which is similar to a camera. Light and images from outside refract in cornea and lens layer and reach vision point on the retina. In a normal eye, rays from outside refract in cornea and lens and fall into vision center, creating a clear image. But in some cases, clear images may not be created on the retina depending on the structure of cornea, lens and the eye.
Myopia, which is defined as being nearsighted, is a condition where the rays that come to the eye focus in front of retina. It is a structural feature and its genetic inheritance is common. It usually starts at school age and shows an increase as the growth process continues.
In general, it is failure to see near objects. Structural and hereditary characteristics are the most common reasons of hyperopia. Untreated hyperopia increases the risk of amblyopia in children . Therefore, all preschool children should have an eye examination.
Astigmatism is an eye condition that makes blurred vision at all distances. It can either be structural or develop as a result of degenerative diseases, infections and trauma causing a change in cornea layer.