A contact lens is a thin lens placed directly on the surface of the eye. Contact lenses are considered medical devices and can be worn to correct vision, or for cosmetic or therapeutic reasons. People choose to wear contact lenses for many reasons. Aesthetics and cosmetics are often motivating factors for people who would like to avoid wearing glasses or would like to change the appearance of their eyes. When compared with spectacles, contact lenses typically provide better peripheral vision and do not fog up like glasses can. This makes them ideal 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. Additionally, there are corneal conditions such as keratoconus and aniseikonia that are typically corrected better by contacts than by glasses.
A spherical contact lens bends light evenly in every direction. They are typically used to correct myopia and hyperopia. A toric contact lens has a different focusing power horizontally than it does vertically, and as a result can correct for astigmatism. Some spherical rigid lenses can also correct for astigmatism. Because a toric lens must have the proper orientation to correct for a person’s astigmatism, it must have additional design characteristics to prevent the lens from rotating away from the ideal alignment. This can be done by weighting the bottom of the lens or by using other physical characteristics to rotate the lens into the proper position. Some toric contact lenses have marks or etchings that can assist the eye doctor in fitting the lens.
The correction of presbyopia (a gradual loss of the focusing ability of the eyes that begins around the age of 40) presents an additional challenge in the fitting of contact lenses. Presbyopic patients require different prescriptions for distance and near. Two main strategies exist: multifocal contact lenses and monovision. Multifocal contact lenses are comparable to bifocals or progressive lenses because they have multiple focal points, correcting both distance and near in each eye. Monovision is the use of single vision lenses (one focal point per lens) to focus one eye for distance vision (typically the person’s dominant eye) and the other eye for near work. The brain then learns to use this setup to see clearly at all distances. Alternatively, a person may simply wear reading glasses over their distance contact lenses, which provides the most optimal vision at all distances.
Contact Lens Types/Design
Advances in contact lens design and materials have made them a clear, comfortable option for many people requiring vision correction. Our office has extensive training and experience in fitting most popular styles of contact lenses, including:
- Rigid gas permeable
- Soft lenses – daily disposable, monthly replacement, and extended wear
- Toric lenses (for astigmatism)
- Fashion Color Lenses