Types of Contact Lenses
There are two main types of contact lenses used to correct vision disorders: soft and rigid gas-permeable (RGP). The old hard lenses which were used exclusively in the 1960's are still available but have been replaced because RGP's correct vision the same but allow oxygen to get to the cornea. Your optometrist will determine which type is the best for your individual needs.
Rigid Gas-Permeable Contact Lenses
The name came from the fact that it looked like the old hard lenses but was made from a type of plastic that oxygen could pass through. Oxygen permeability is necessary for long term corneal health. RGPs are custom-made for a patient which means more types of vision disorders can be corrected compared to soft lenses. RGPs also allow more oxygen to the cornea compared to soft lenses. RGPs are now made from materials such as silicone and fluorine combined with a plastic called polymethylmethacrylate. The average life for RGPs is two years. They are not available in a tint that will change your eye color. RGPs come in daily or extended wear and are often the lens of choice for people with high degrees of astigmatism. Another instance where RGPs excel is they slow the progression of nearsightedness.
Soft Contact Lenses
Soft lenses are available in many different types and colors. They are made from a plastic combined with water in most cases. Soft lenses are not as deposit resistant as RGPs and require more frequent replacement. Your optometrist evaluates many factors when deciding which lens and discard cycle is right for you. Soft lenses come in a variety of wearing options. They include:
Daily Wear Conventional
To be taken out daily and cleaned and disinfected. Have an average life of 6-12 months
Extended Wear Conventional
FDA-approved to be worn up to six nights and then removed. Average life 6-12 months.
Daily Disposable
Single use lenses to be removed before sleeping and discarded.
Two Week Disposable
May be removed at night or worn overnight up to six nights and then discarded at two weeks.
Planned Replacement
May be worn daily or overnight up to six nights and replaced every one to three months depending on the patient and lens.
*Success of overnight wearing of contact lenses is dependent on the person's eye not the contact lens. Just because a lens is approved for extended wear does not mean you will be successful with that schedule. Follow-up care by your optometrist is even more important when you sleep in contact lenses because of the increase in risk of infection.
