People choose to wear contact lenses for many reasons.Aesthetics and cosmetics are the main motivating factors for people 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, and do not collect moisture (from rain, snow, condensation etc.) or perspiration; 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 or worry about compatibility with glasses. Additionally, there are conditions such as keratoconus and aniseikonia that are typically corrected better with contact lenses than with glasses
Contact lenses are classified in many different ways: by their primary function, material, wear schedule (how long a lens can be worn), and replacement schedule (how long before a lens needs to be discarded).
Corrective 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 (horizontally, vertically, etc.). They are typically used to correct myopia and hypermetropia. A toric contact lens has a different focusing power horizontally than 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, such a lens must have additional design characteristics to prevent it 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 back into position. Some toric contact lenses have marks or etchings that can assist the eye doctor or the user in fitting the lens.
Correction of presbyopia (a need for a reading prescription different from the prescription needed for distance) presents an additional challenge in the fitting of contact lenses. Two main strategies exist: multifocal lenses and monovision.
Multifocal contact lenses (e.g. bifocals or progressives) are comparable to spectacles with bifocals or progressive lenses because they have multiple focal points. Multifocal contact lenses are typically designed for constant viewing through the center of the lens, but some designs do incorporate a shift in lens position to view through the reading power (similar to bifocal glasses).
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 technique called modified monovision uses multifocal lenses and also specializes one eye for distance and the other for near, thus gaining the benefits of both systems. Alternatively, a person may simply wear reading glasses over their distance contact lenses. Care is advised for persons with a previous history of strabismus and those with significant phorias, who are at risk of eye misalignment under monovision. Studies have shown no adverse affect to driving performance in adapted monovision contact lens wearers.
A cosmetic contact lens is designed to change the appearance of the eye. These lenses may also correct refractive error.
Some colored contact lenses completely cover the iris, thus dramatically changing eye colour. Other colored contact lenses merely tint the iris, highlighting and beautifying its natural colour. 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
Our friendly optometrist will help determine whether you are suitable for contact lenses by performing comprehensive eye examination : which include checking if your eyes are healthy enough to wear them, measuring the curve of your eyes to determine the right parameters of the lenses, to determine the prescription of the lenses and to ask you the occasions when you would be wearing them.
Find out about them below, or contact us for a consultation with our friendly qualified optometrist.
• Multifocal Contact Lens
• Colour Contact Lenses
• Keratoconus Contact Lens
• Contact Lens for Astigmatism
• Daily Contact Lenses
• Biweekly Contact Lens
• Monthly Contact Lens
• Rigid Gas Permeable (RGP) Lens
• Silicon Hydrogel and Hydrogel Contact Lens