Contact lenses (or simply contacts) are small plastic disks for the improved vision people wear in front of their corneas. Like glasses, contact lenses correct the vision problems caused by refractive errors. These errors are generally myopia (nearsightedness), hyperopia (farsightedness), astigmatism (distorted vision), and presbyopia (changes to near vision due to old age).
Contacts are an excellent substitute for people who do not think they look good with glasses or undergo LASIK surgery. Primarily, aesthetics and cosmetics are the prime drives for contacts. It is no wonder that these ocular prosthetic devices are worn by over 150 million people worldwide, making them one of the most popular lens correction methods.
Following are some essential points one should know before deciding whether they would like to get a pair of contact lenses.
Contact Lens Material
Following is a list of the material composition of different kinds of contact lenses:
- 64% silicone hydrogel
- 22% hydrogel
- 11% gas permeable
- 2% hybrid
- 1% PMMA
Hydrogel is a compound consisting of water-contained plastics. They are thinner and more pliable. In contrast, the soft hydrogel is more porous and allows oxygen to get to the cornea. Silicone hydrogel contacts are the most popular lenses used today. When combined with the gas permeable lens material, you get yourself the hybrid kind.
Gas permeable contacts are rigid contact lenses, although they allow oxygen to reach the eyeball. The PMMA lenses are plastic lenses that are usually shatterproof and are generally available in the market under the trademark names of Plexiglass, Perspex, and Lucile.
Types of Contact Lenses
There are various types of contact lenses based on the plastic material used in them. The broader types of lenses are hard and soft contact lenses.
The hard lenses are the most commonly used rigid, gas-permeable (RGP) lenses. These lenses have many other additives to the original plastic mix. Even though they are tough, they allow oxygen to pass, hence the name “permeable.”
Soft lenses are the type of lenses that are mainly prescribed for myopia and hyperopia. They have fixed wearing times and need proper washing and maintenance. They are different from hard lenses because they are comfortable and easier to wear.
Some other types include bandage lenses (used after surgery and injury) and Toric contacts, which correct the vision for people who have astigmatism, even though hard lenses do a much better job than these contacts.
Wearing Time for Soft Lenses
So two types of contact lenses are available in the market are:
- Daily Wear
- Extended Wear
For daily wearers, the lenses must be removed before going to bed at night. For extended wearers, they can use the lenses for seven consecutive days, and they do not need to remove them every night routinely.
It is healthier not to extend the lens wearing time, and they should be regularly cleaned to prevent eye infections and other residue buildups.