Contact lenses are an excellent choice for nearly anyone who needs vision correction and doesn't want to wear eyeglasses full time or undergo LASIK surgery.
Here are the basics you should know about contact lenses before seeing your eye doctor if you are interested in wearing contacts.
Contact Lens Materials
The first choice when considering contact lenses is which lens material will best satisfy your needs. There are five types of contact lenses, based on type of lens material they are made of:
CONTACT LENS MATERIAL
Soft lenses are made from gel-like, water-containing plastics called hydrogels. These lenses are very thin and pliable and conform to the front surface of the eye. Introduced in the early 1970s, hydrogel lenses made contact lens wear much more popular because they typically are immediately comfortable. The only alternative at the time was hard contact lenses made of PMMA plastic.
Silicone hydrogel lenses are an advanced type of soft contact lenses that are more porous than regular hydrogel lenses and allow even more oxygen to reach the cornea. Introduced in 2002, silicone hydrogel contact lenses are now the most popular lenses prescribed in the United States.
Gas permeable lenses — also called GP or RGP lenses — are rigid contact lenses that look and feel like PMMA lenses (see below) but are porous and allow oxygen to pass through them. Because they are permeable to oxygen, GP lenses can be fit closer to the eye than PMMA lenses, making them more comfortable than conventional hard lenses. Since their introduction in 1978, gas permeable contact lenses have essentially replaced nonporous PMMA contact lenses. GP contacts often provide sharper vision than soft and silicone hydrogel contacts — especially if you have astigmatism. It usually takes some time for your eyes to adjust to gas permeable lenses when you first start wearing them, but after this initial adaptation period, most people find GP lenses are as comfortable as hydrogel lenses.
Hybrid contact lenses are designed to provide wearing comfort that rivals soft or silicone hydrogel lenses, combined with the crystal-clear optics of gas permeable lenses. Hybrid lenses have a rigid gas permeable central zone, surrounded by a "skirt" of hydrogel or silicone hydrogel material. Despite these features, only a small percentage of people in the Kenya. wear hybrid contact lenses, perhaps because these lenses are more difficult to fit and are more expensive to replace than soft and silicone hydrogel lenses.
PMMA lenses are made from a transparent rigid plastic material called polymethyl methacrylate (PMMA), which also is used as a substitute for glass in shatterproof windows and is sold under the trademarks Lucite, Perspex and Plexiglas. PMMA lenses have excellent optics, but they do not transmit oxygen to the eye and can be difficult to adapt to. These (now old-fashioned) "hard contacts" have virtually been replaced by GP lenses and are rarely prescribed today.
Contact Lens Wearing Time
Until 1979, everyone who wore contact lenses removed and cleaned them nightly. The introduction of "extended wear" enabled wearers to sleep in their contacts. Now, two types of lenses are classified by wearing time:
Daily wear — must be removed nightly
Extended wear — can be worn overnight, usually for seven days consecutively without removal
"Continuous wear" is a term that's sometimes used to describe 30 consecutive nights of lens wear — the maximum wearing time approved by the FDA for certain brands of extended wear lenses.
When To Replace Your Contact Lenses
Even with proper care, contact lenses (especially soft contacts) should be replaced frequently to prevent the build-up of lens deposits and contamination that increase the risk of eye infections.
Soft lenses have these general classifications, based on how frequently they should be discarded:
When To Replace Your Contact Lenses
Lens Replacement Frequency
Daily disposable lenses — Discard after a single day of wear
Disposable lenses — Discard every two weeks, or sooner
Frequent replacement lenses — Discard monthly or quarterly
Traditional (reusable) lenses — Discard every six months or longer
Gas permeable contact lenses are more resistant to lens deposits and don't need to be discarded as frequently as soft lenses. Often, GP lenses can last a year or longer before they need to be replaced.
The most frequently prescribed contact lens replacement schedule in the Kenya. in 2019 was monthly (40 percent), followed by daily (35 percent), every one to two weeks (24 percent) and annually (1 percent).
If you are looking for contact lenses in Kenya, please visit us: Lions SightFirst Eye Hospital to be examined by our specialised Doctors or You can reach us on 0728 970 601 or 0733 619 191 or Email: email@example.com