Understanding Hard Contact Lenses

Roughly 85 percent of those who wear contact lenses wear soft lenses, but there is still a need for hard contact lenses in a small percentage of the contact lens wearing population. Fortunately for those individuals, hard contact lenses have become much more comfortable than the original hard contacts that were developed in the 1960s. The two types of hard contacts are polymethyl methacrylate (PMMA) and rigid gas-permeable (RGP) contacts. The PMMA contacts consist of a stiff plastic while the RGP contacts combine other materials such as silicone with the plastic to form a lens which allows more oxygen to reach the eye. The increased flexibility combined with increased permeability makes RGP contacts much more comfortable than PMMA contacts. Although hard contact lenses are much less widely used than soft contacts there are some situations which make the use of hard contacts necessary. These situations include: • An astigmatism which cannot be corrected by a soft lens • Allergies to elements used in soft contacts • Individuals who have a propensity to produce excessive protein buildup