Hard contact lenses are rigid gas permeable. This means that they are porous enough to allow oxygen to enter through to the cornea. Hard contact lenses keep their shape on the eye. As such, they are sometimes recommended to curb the progression of nearsightedness in younger wearers.
Soft contact lenses are popular because they are very comfortable for the wearer. Soft contact lenses don’t “pop out” the way hard lenses occasionally might. Soft lenses are appropriate to correct near and farsightedness and astigmatism.
Intended to be worn for a short time, to help prevent allergic reactions or bacterial infections in sensitive wearers. Disposable lenses are also appropriate for children who might not take excellent care when cleaning their lenses.
Extended wear contact lenses are designed to be worn constantly for long periods of time – up to a week. They do need to be deep cleaned weekly, however. Unlike all other lenses, extended wear contacts can be worn while sleeping. The lens type allows sufficient oxygen to reach the eye for health.
Most contact lenses are daily wear. That is they are worn all day and then removed at night for cleaning. These lenses generally last until their given expiration date, at which point they must be discarded and replaced because the lens material begins to break down.
These are worn to enhance or completely change the visual color of the iris. They are still prescription contact lenses, however, and need to be treated with the same care you would give to regular lenses. Many — but not all — brands of contact lens companies offer colored lens options.