Silicone hydrogel contact lenses are advanced soft lenses that allow more oxygen to pass through the lens to the cornea than regular soft ("hydrogel") contacts. In fact, silicone hydrogel lenses enable up to five times more oxygen to reach the cornea than regular hydrogel lenses.
All contact lenses reduce the amount of oxygen that reaches the front surface of the eye to some degree. When the cornea's oxygen supply is significantly reduced — a condition called hypoxia — a number of problems such as red eyes, corneal swelling, blurred vision and eye discomfort can occur. Hypoxia also can increase contact lens wearers' risk for a number of eye infections.
Silicone hydrogel lenses were introduced in hopes of decreasing hypoxia-related problems and increasing the safety of both daily wear and extended wear of soft contact lenses.
It's also likely that due to their increased oxygen transmissibility, silicone hydrogel lenses have enabled many people to comfortably wear contacts for longer hours than they could have with regular hydrogel lenses.
Advantages of silicone hydrogel lenses over conventional soft lenses include: more resistance to protein deposits, less drying of the lenses, lower risk of eye infection, easier handling due to increased rigidity of material, and much lower incidence of complications with extended wear use (overnight wear).
The biggest difference patients can tell is the comfort level versus conventional contacts. Also, silicone hydrogel contacts help minimize problems like redness, dryness, swelling of the cornea and corneal infections. Plus, any infections that do come about tend to be less aggressive and more treatable. Silicone hydrogel lenses allow more oxygen to the cornea which results in better eye health.
Most people benefit from wearing silicone hydrogel lenses as compared to conventional soft lenses. This is due to the health advantages however; these lenses are especially useful in the following types of patients:
Patients with high prescriptions
Patients whose eyes show signs that they require more oxygen
Patients who experience end of day discomfort, dryness, or redness with their conventional soft lenses
Patients who work long hours in low humidity air conditioning
Patients who wear their lenses for more than 12 to 14 hours a day, including overnight wear
Younger patients who tend to ‘over-wear’ their lenses
