Main Types of Refractive Errors

In our eyes, the front surface (cornea) and the lens inside the eye to form "convergence system (focus)" eyes and is primarily responsible for the concentration (focus) light rays on the surface of the retina, very like the lens of a camera ray mengfokus on the film. In a perfect optical system, the strength of the cornea and lens are perfectly matched with the length of the eyes and the pictures are in focus; any discrepancies on this system is called a refractive error (refractive error), and the result is a blurred image at several locations .

Myopia (nearsighted): In people with myopia, a mismatch in the power of concentration (focus) and the length of the eye causing distant objects are blurred and near objects more clearly.

Hyperopia (eye distance): In people with hyperopia, the discrepancies in the power of concentration (focus) and eye length causes nearby objects are blurred and distant objects are relatively clear.

Astigmatism: In people with astigmatism, one of the shape of the cornea or lens shape distorted, causing a variety of images on the retina. This causes the objects at all distances appear blurred. Many people have a combination of one of the myopia or hyperopia with astigmatism.