Light filtering colored lenses are the latest product in this field and they are designed to serve athletes and sport buffs in improving their game. To enhance visibility of the ball in tennis, softball or golf, the lenses are designed to augment all yellow and orange shades by tamping down other, more blue-based colors. This allows the athlete to see the ball more clearly, to track its fat motion and have more time to react appropriately. It's also used by spectators. These are purely functional contacts that have no effect of the eye color of the wearer, but only on his/her vision.
Colored or tinted contacts , unlike light filtering lenses, have no influence of the eyesight of the wearer unless they are also prescription contacts. They are purely for personal use and for anyone who wants to change their eye color drastically. They can be found in a wide variety of colors, from all shades of brown, blue, greens and grays. If your natural eye color is brown, then for dramatic effect you might choose contact lenses in violet, green, or blue. Colored lenses are essentially opaque tints made of solid color, though the more expensive variety are even truer to reality and are designed in retina strips that can fool even close examination. Some are cleverly designed in blots and lines of color or tiny tinted dots of various mild shades to look even more natural on the eye. The obviously unnatural ones, such as slit cat-eyes fit for costumes or theatrical lenses have been long featured in the cinema and on television. They can now be bought in novelty shops, though for the most part these are the disposable variety. If you want anything for a longer period of time, ask your eye practitioner for information on that.
Enhancement tints don't actually change the color of your eyes as drastically as colored lenses, but they do enhance your natural eye color. They are usually solidly tinted in pale translucent shades. If you have pale blue eyes and want the color deepened and darkened a little, you could take gray, green or violet enhancement tints. If you pale brown eyes you could take dark green lens to give the color a more hazelnut shade.
The largest demographic of people buying enhancement tints are people already using contacts. You can get your regular prescription contacts tinted for color enhancement and serve both interests- functional and aesthetic. These lenses are usually used by very people with very pale colored eyes who want their eyes to stand out a bit more. The last type of lens is the visibility tint that is simply added to the lens in order to facilitate putting it in and getting it out. Visibility tints are usually very pale blue or green or brown and they don't affect eye color or eyesight at all.