Myopia or Nearsightedness is a condition when the distance between the cornea and the retina is too long or the actual shape of the cornea or clear window of the eye is too steep. This causes light images to focus in front of the retina, causing blurry vision in the distance.
The eye functions by focusing images i.e. the stop sign on the left in the picture. There are two ocular structures that achieve this focusing, the cornea (or the clear window of the eye) and the natural lens (much like the lens in a camera).
Together they focus or compress the parallel light rays onto the retina (back structure of the eye, much like the film in a camera). The image is displayed on the retina and a photochemical reaction occurs. The image is then transmitted through the optic nerve to the brain where we actually see and interpret the image as clear or blurry.
In myopia, the eye is to long or the cornea is to curved and the image doesn’t strike the retina exactly correct, it strikes in front of the retina. This is represented in the picture by the stop sign in the middle. Since it misses the retina, the image you see is blurred (the stop sign on the right).
LASIK to Correct Myopia
The Myopia can be corrected with LASIK surgery. What laser vision correction does is correct the refractive error by changing the shape of the cornea to permit perfect image placement on the retina and compensate for the nearsightedness.