The main components of the human eye are the retina, lens, and cornea. The cornea bends the light so that an image is projected onto the retina.
The retina, made up of photoreceptor cells called rods and cones, receives the light and transmits impulses along the optic nerve to the optical region of the brain.
While it is the cornea’s job to get the image to the retina, it is the lens’ job to make sure the rays come to a sharp focus on the retina.
In nearsightedness, the cornea places the image in front of the retina. In farsightedness, the opposite occurs in that the image is placed behind the retina. Both nearsightedness and farsightedness occur because the cornea shape is not exactly what it should be.
Astigmatism, also caused by cornea shape anomaly, is a condition in which the cornea’s curvature is asymmetrical. In astigmatism the eye is shaped like a football or egg instead of the normal baseball shape.
Light rays are focused at two points on the retina rather than one, resulting in blurred vision. Any change in the cornea shape means the image is not where it should be and hence blurry vision.
In LASIK eye surgery, a excimer laser destroys the inter-molecular bonds within the cornea tissue which results in giving the cornea it’s correct shape. The cornea can then place the image onto the retina. The procedure for LASIK eye surgery can be characterized as follows: