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were the first hard contact lens developed. They could not be tolerated for long periods of time and are no longer prescribed. PMMA (polymethyl metacrylate), or Plexiglas, lenses were developed to replace the glass lens. They were lighter but still uncomfortable. Plexiglas lenses caused corneal damage due to decrease oxygen flow. They are still available but rarely prescribed. Rigid Gas Permeable (RGP) lenses are the most prescribed hard contact lens today.
Rigid gas permeable lenses are made of a hard material that allows increased oxygen flow as compared to the PMMA lens. Therefore it avoids the corneal damage caused by its predecessor. RGP lenses offer many other benefits to the contact lens wearer.
ADVANTAGES OF RIGID GAS PERMEABLE LENSES
&bullRetain shape better than
&bullProvide better vision than soft contact lenses
&bullIncrease durability, lasting up to a year
&bullLess costly due to increase durability
&bullCan be worn occasionally or regularly when cared for properly
&bullIncrease visual clarity
&bullTreats astigmatism and karatoconus well as the lens can be formed to correct such problems
&bullEffectively treats presbyopia
&bullUsed to correct the cornea shape during sleep
&bullCan slow down the progression of near-sightedness in children
DISADVANTAGES OF RIGID GS PERMEABLE LENSES
&bullTake longer for the wearer to adjust to and achieve max comfort than soft contact lenses
&bull"spectacle blur"- a blurring of the vision that occurs when the contacts are removed that may last for a period of time
&bullRequires greater care during cleaning
Rigid Gas Permeable lenses are equal if not better than soft contact lenses but thye are much less popular because they are usually uncomfortable to wear. Speak with your optometrist to determine what is best for you.