Advantages and disadvantages of gas permeable lenses

Saturday, September 19th, 2009 at 2:52 pm Post in Contact Lenses

Also called RGPs, rigid gas permeable or oxygen permeable lenses, gas permeable (GP) contact lenses are less-known than soft lenses. RGPs are different from “hard” contact lenses, which have disappeared today, although they were popular before the invention of soft lenses in 1971. PMMA hard lenses are uncomfortable and prohibit oxygen from passing through the lenses.

Invented in the late 1970s, GP lenses contain silicone, which is more flexible than PMMA and allows more oxygen to pass through, creating more comfort and better vision. They also have many other advantages, such as more durable and deposit resistant, easier to clean, and less expensive. However, GP lenses demand a longer adapting period than soft lenses.

GP lens is the right solution for people unsatisfied with soft lenses, such as vision fussy individuals, people with astigmatism, presbyopia or keratoconus, or individuals after a refractive surgery. GP lenses offer the best answer for bifocal lenses for people with presbyopia. Ortho-k lenses also use GPs.

GP lenses are not flawless. They require a regular wearing for most comfort and a longer time to adjust, which never happen to soft lenses. GPs may still cause blurry eyes when they are removed, even if the situation will soon disappear. GP lenses also need more careful cleaning and storing since they last at least one year.

Currently, new versions of lenses that combine the visual clarity from GPs and comfort from soft lenses are available, which remove the most significant obstacle for GPs. These special lenses are used for presbyopia, keratoconus and LASIK recovery.