The Health Nut Blog

RGP Contact Lenses

One of the most important factors in eye health is continual exposure to air. Oxygen helps keep all tissues healthy and the eyes are no exception. But all contact lenses reduce the oxygen that contacts the eyes somewhat, some more than others. In the past, that 'somewhat' was substantial. That's why rigid gas permeable (RGP) contact lenses were invented.

RGP lenses are made from a combination of a polymer called PMMA, silicon and fluoropolymers that allow several times more oxygen to diffuse through the lens itself than other types. Some older contact lens material permitted none. Air migrated into the tear solution when the lens moved slightly during blinking. That helps keep eyes bathed with oxygen to degrade protein buildup, micro-organisms and other things that would increase the odds of infection or other eye problems.

RGP lenses are midway between a soft lens and a hard lens. That gives them a good balance of comfort while providing enough rigidity to correct mild cases of astigmatism, which soft lenses can't do. For other cases of astigmatism, toric lenses are available in an RGP style. That firmness makes them useful for correcting mild cases of corneal warpage as well. Other out-of-shape conditions, like keratoconus, a disease in which the cornea becomes somewhat cone shaped, respond better to RGP lenses, too.

Their rigidity helps make a highly accurate lens. Since they're firmer, they retain their shape better when blinking and during normal movement. The eye does flex minutely, though, under normal circumstances. RGP lenses are flexible enough to move with it, making for a good fit and very sharp optics. That same firmness makes them better suited to making bifocal lenses than a soft contact lens, too.

RGP contact lenses also tend to last longer than soft lenses. The typical RGP lens will last more than a year before requiring replacement. They're made of durable material that is less likely to rip or scratch than soft contact lenses.

One effect of the material is that they don't draw moisture from the eye. That makes them comfortable to wear, after an initial adjustment period. Soft lenses, while comfortable immediately, absorb tear solution from the eye, causing the eye to dry out a bit more after a few hours of wear. And because they are highly oxygen permeable RGP lenses can be worn for longer periods with less chance of protein or bacteria buildup.

Also, because they resist protein buildup better than other types, they're easier to keep clean and sterile. RGP lenses do require a slightly different type of cleaning solution, though, so be sure to get the right kind when ordering this style.

RGP lenses are not for everyone. But if your eye care professional recommends them, you're sure to find they suit you well.

# posted by NeilG @ 2:06 AM