Types of contact lenses
23 Sep 2010
contact lenses can be divided into several groups on the following parameters:
For elasticity and materials
Hard contact lenses
Hard contact lenses are used primarily for vision correction in complex cases (they are not interchangeable at high degrees of astigmatism and keratoconus) and orthokeratology. Hard lenses can achieve an increase in visual acuity because they retain their shape. They are really tough, so they require particularly careful handling. At the same time, the hard lenses have several advantages: the number of protein deposits on them is much smaller, and they rarely cause allergic reactions. These lenses require individual selection and production.
Soft contact lenses
Soft contact lenses are about 90% of users of contact lenses in the world. They are used to correct myopia, hyperopia, astigmatism and hyperopia senile, as well as to enhance or change eye color. The range of + 20D to -20D. Soft contact lens covering the iris and takes the shape of the eye. It is held in tension by means of eye tear fluid (capillary effect). These lenses have a high probability of not accidentally shift or fall out of the eye.
The frequency of replacement
Contact lens manufacturer's recommended maximum amount of time of use, after which the lenses must be replaced with new ones.
Traditional contact lenses
Lifetime soft contact lenses from 6 months to a year (annual contact lenses). The service life of hard contact lenses over a year (several years).
Contact lenses are planned replacement
According to regulations, the manufacturer require replacement after 1-6 months.
- Monthly contact lenses
- Three contact lenses
- Six months
Contact Lenses frequent routine replacement
Have a service life from one day to two weeks.
- Daily lenses
- Weekly
- Two-week lens
By wearing mode
Contact lens manufacturer's recommended maximum amount of time for which the lenses can be worn without removing.
Daily contact lenses
Dress lenses are removed in the morning and evening before bedtime.
Contact lenses are flexible wearing mode
The lenses can be worn 1-2 days without taking the night.
Contact lenses regime prolonged wearing
Lenses dress for 7 days and removed at night.
Contact lenses wearing continuous mode
The lenses can be worn continuously for thirty days without removing them at night. This mode is only available for some silicone hydrogel lenses. For its use should consult a physician ophthalmologist.
Note: The service life / use of contact lenses is highly dependent on the mode of wear. In the case of prolonged service life of wearing contact lenses according to manufacturer's regulations should be reduced by 2-3 times, and for silicone lenses - they must be discarded after a session continuous wear of more than a week.
By design
Spherical lenses
They are used to correct myopia (nearsightedness) and hypermetropyy (hyperopia).
Toric contact lenses
They are used to correct myopia (nearsightedness) and hypermetropyy (hyperopia) in the presence of astigmatism.
Multifocal contact lenses
They are used to correct presbyopia (farsightedness senile).
Note: By design available broken down in terms of the method of contact lens. Certainly lens design is the secret of each company, although it for marketing purposes, in one form or another, is declared.
By appointment
Optical lenses
They are used to correct vision defects (refractive errors).
Cosmetic contact lenses
They are used to correct various congenital or acquired as a result of trauma, eye defects such as Kolob iris, corneal opacity and so on. AP
Therapeutic contact lenses
This is mainly soft contact lenses, which due to its hydrophilic bandazhnaya can be used as protection of the cornea, as well as a reservoir for prolonged delivery of drugs to the eye tissue.
Decorative contact lenses
Shades of decorative contact lenses
Colored decorative contact lenses
Decorative contact lenses Crazy
They put a variety of drawings or effects. Decorative contact lens wear Crazy mainly going to a disco or a party, use in film industry to create eye vampires, aliens and other characters with unusual eyes.
Contact lenses for sports
Recently, major manufacturers of contact lenses are developing special lenses for specific sports. For example, there were lenses that selectively increase the contrast detection yellow ball for tennis and softball.
The degree of transparency
Transparent contact lenses
Painted contact lenses
Some soft contact lenses have little color to what would make it easier to identify the solution in which they are stored. However, they do not alter the shade of the eyes.
For the ability to absorb ultraviolet rays
Contact lenses absorb UV rays
Lenses pohlaschaet UV rays protect your eyes from the harmful effects of ultraviolet radiation. For more information about the impact of UV radiation on the eye can be found here.
Contact lenses do not absorb ultraviolet rays
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