To restore natural vision and comfort, there are several types of contact lens materials which could be designed for nearsightedness, farsightedness, astigmatism, presbyopia, keratoconus, myopia control, dry eye, etc.
Soft contact lenses
The most common contact lenses are soft contact lenses. They are made of a hydrophilic or “water loving” soft plastic material that drapes over the eye and rests on a layer of tears. The water content of soft contact lenses allows oxygen to pass through the lens to provide crisp and stable vision. Many new wearers easily adapt to these lenses.
Silicone Hydrogel Lenses
Contact lenses made of silicone hydrogel now account for nearly half of all newly fitted contact lenses. This new lens material provides a hyper-oxygen permeable flow to the cornea, resists protein deposits on the lens, enhancing comfort and enabling contact lenses to be worn on a daily basis, or, in certain cases, overnight for up to 30-days continuous wear. Silicone hydrogel lenses can also include components that keep them moist on the eye. Some contact lens manufacturers now offer a second generation silicone hydrogel contact lens that improves comfort in dry environments like air-conditioned offices and airliner cabins.
The latest generation of contact lenses have been developed by manufacturers who want lenses that achieve longer hours of comfort by creating lenses which mimic the 78% water content of the cornea and mimic a layer of the tear film that prevents dehydration.
Oxygen permeable contact lenses
A second option is oxygen permeable contact lenses. These lenses are made of a rigid polymer that also rests on the eye’s layer of tears. Oxygen permeable contact lenses provide crisp and stable vision, and their enhanced permeability promotes good eye health. Some eye care professionals prescribe these lenses for patients with slight irregularities in the cornea. The rigid nature of the lens smoothes out these irregularities and improves acuity. If irregularities are pronounced, custom lenses can be generated from computer-guided lathes. Oxygen permeable contact lenses require an initial adaptation period of a few weeks.