People choose to wear contact lenses for many reasons. Aesthetics and cosmetics are the main motivating factors for those who want to avoid wearing glasses or to change the appearance of their eyes.
Others wear contact lenses for functional or optical reasons. When compared with spectacles, contact lenses typically provide better peripheral vision. This can make them preferable for sports and other outdoor activities. Contact lens wearers can also wear sunglasses, goggles, or other eyewear of their choice without having to fit them with prescription lenses or worry about compatibility with glasses.
Some conditions such as keratoconus and aniseikonia are typically corrected better with contact lenses than with glasses.
The average age of contact lens wearers globally is 31 years old, and two-thirds of wearers are female.
Lens Design
Corrective spherical contact lenses are designed to improve vision, most commonly by correcting refractive error. This is done by directly focusing light so it enters the eye with the proper power for clear vision.
A spherical contact lens bends light evenly in every direction (equally horizontally and vertically). They are typically used to correct myopia, (short sightedness) and hypermetropia (far sightedness).
Monovision is the use of single-vision lenses (one focal point per lens) to focus an eye (typically the dominant one) for distance vision and the other for near work. The brain then learns to use this setup to see clearly at all distances.
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 colour are far less common, accounting for only 3% of contact lens fits.
Due to their medical nature, coloured contact lenses, similar to regular ones, are illegal to purchase without a valid prescription. Those with perfect vision can buy colour contacts for cosmetic reasons, but they still need their eyes to be measured for a "zero" prescription. This is for safety reasons, so the lenses will fit the eye without causing irritation or redness.
