During nearsightedness or myopia, is the cornea enlarged or smaller than normal?

Question

I really need information.

Answer 1

Hi Joshuayap!
Myopia most often occurs because the eyeball is too long, rather than the normal, more rounded shape. Another less frequent cause of myopia is that the cornea, the eye’s clear outer window, is too curved. In other word, Myopia is the cornea enlarged (eyeball is too long or the cornea has too much curvature).

Our ability to "see" starts when light enters the eye through the cornea. The shape of the cornea, lens and eyeball help bend (refract) light rays in such a manner that light is focused into a point precisely on the retina.

In contrast, if you are nearsighted, the light rays from a distant point are focused at a place in front of the retina. As the light will only be focused in that one place, by the time it reaches the retina it will have "defocused" again, forming a blurred image.

Jason Homan

Answer 2

First undertstand that every structure that light passes through is part of the focusing of that light image on the retina of the eye. These structures include the cornea, the aqueous humor, the lens of the eye, the viterous body. The shape of the eyeball itself will also to a large degree determine where the focused image occures either directly on the retina, where you want it, or behind or in front of the retina, where you don't want it. As we age the lens becomes less elastic and this is the major cause of myopia with age, or presbyopia. Laser surgery works because it will alter the cornea by removing tissue from the cornea and refocusing the light. So you can have a perfectly normal cornea and yet have visual difficulties.

Answer 3

Myopia, or nearsightedness also known as short sightedness, is a refractive defect of the eye in which collimated light produces image focus in front of the retina when accommodation is relaxed.
Those with myopia typically can see nearby objects clearly but distant objects appear blurred.
Simple myopia is more common than other types of myopia and is characterized by an eye that is too long for its optical power (which is determined by the cornea and crystalline lens) or optically too powerful for its axial length. Both genetic and environmental factors, particularly significant amounts of near work, are thought to contribute to the development of simple myopia.