How the Eye Works


      
To better understand Laser Vision Correction Surgery and how these techniques may be used to correct vision problems resulting from refractive error, a short review of how the eye works may be helpful.

The eye can be described as a sophisticated camera consisting of two lenses in front, which focus light rays upon the retina in the back part of the eye.  The retina then turns the focused image into an encoded electrical signal transmitted by the optic nerve to the visual center of the brain where we actually perceive sight.

The two focusing elements of the eye are the cornea and the lens.  The cornea is the clear tissue covering the iris or colored part of the eye.  The crystalline lens is immediately behind the iris and serves to allow the eye to focus at different distances by changing shape.  As the lens becomes less pliable with maturity, this ability is progressively lost (called presbyopia) necessitating our use of reading glasses or bifocals usually starting after age 40.

Problems with the natural focusing (refractive) mechanisms of the eye generally result from a mismatch of the focusing power and the length of the eye.  Most focusing problems develop in a person's teens early twenties. The most severe problems develop in early childhood (before age of 10). Such focus or refractive problems are determined by family genetics (similar to body height, as an example).

In addition to those vision problems you've probablyheard of before the lower order aberrations like nearsightedness and farsightedness there are common vision problems known as higher order aberrations that can also affect your vision. Higher order aberrations are widely believed by ophthalmic experts to contribute to common night vision problems, including glare and halos.