GLASSES MAY BE REQUIRED FOR:
Light rays entering the eye focus in front of the receptor cells in the retina. Myopes may see clearly at near but are blurred at distance.
Light rays entering the eye focus behind the retina. The eye has to exert extra focusing power to see clearly at distance and even more so at near. If the hyperopia is large then the eye may not be able to focus the image clearly at all. Most young children have mild degrees of hyperopia.
Light rays entering the eye focus at different places. It is caused by an irregular surface of the eye. Instead of being perfectly round, the surface of the eye is shaped like a rugby ball lying on its side and is more curved in one plane than the other.
Each eye has a different focus and the worse eye may become lazy. In this situation the glasses treat the difference between the two eyes.
There is a link between the focusing muscle in the eye and the muscles, which draw the eyes together when looking at a near object. Some children with hyperopia are required to exert so much focusing power in their eyes that their eyes turn in. This refractive esotropia may be fully correctable with glasses.