some color-blind people to distinguish colors better. Red-filtering contact lenses can also be an option for extreme light sensitivity in some visual deficiencies such as achromatopsia. ChromaGen contact lenses have been used and shown to have some limitations with vision at night although otherwise producing significant improvements in color vision. An earlier study showed very significant improvements in color vision and patient satisfaction. Later work that used these ChromaGen lenses with people with dyslexia in a randomised, double-blind, placebo controlled trial showed highly significant improvements in reading ability over reading without the lenses. This system has been granted FDA approval for use in the United States. Magnification is another area being researched for future contact lens applications. Embedding of telescopic lenses and electronic components suggests that future uses of contact lenses may become extremely diverse. Cosmetic contact lenses A cosmetic contact lens is designed to change the appearance of the eye. These lenses may also correct refractive error. Although many brands of contact lenses are lightly tinted to make them easier to handle, cosmetic lenses worn to change eye color are far less common, accounting for only 3% of contact lens fits in 2004. In the United States, the FDA labels non-corrective cosmetic contact lenses as decorative contact lenses. Like any contact lens, cosmetic lenses carry risks of mild to serious complications, including ocular redness, irritation and infection. Due to their medical nature, colored contact lenses, similar to regular ones, are illegal to purchase in the United States without a valid prescription. Those with perfect vision can buy color contacts for cosmetic reasons, but they still need their eyes to be measured for a "plano" prescription, meaning one with zero vision correction. This is for safety reasons so the lenses will fit the eye without causing irritation or redness. Some colored contact lenses completely cover the iris, thus dramatically changing eye color. Other colored contact lenses merely tint the iris, highlighting its natural color. A new trend in Japan, South Korea and China is the circle contact lens, which extend the appearance of the iris onto the sclera by having a dark tinted area all around. The result is an appearance of a bigger, wider iris, a look reminiscent of dolls' eyes. Cosmetic lenses can have more direct medical applications. For example, some contact lenses can restore the appearance and, to some extent the function, of a damaged or missing