Depending on how frequently they should be discarded, soft contact lenses are classified as follows:

A)           Daily disposables (to be discarded every single day)

B)            Bi-weekly disposables (to be discarded after two weeks –usually used for daytime wear)

C)            Weekly disposables (to be discarded after one week –usually used for overnight wear)

D)           Continuous wear (to be discarded every four weeks –usually used for 30 day wear)

E)            Planned replacement lenses (to be discarded every few months decided by the eye doctor)

Gas permeable contact lenses do not need to be discarded as frequently as soft contact lenses.  This is because they are more resistant to protein buildup and other lens deposits.  They can be used for a year or longer before they need replacement.

Now let’s talk about contact lens designs.  There are many designs available for the correction of various types of vision challenges.

Spherical contact lenses are typically the rounded designs that correct nearsightedness (myopia) and farsightedness (hyperopia).

Toric contact lenses correct astigmatism as well as myopia or hyperopia.  They are created at different angles.  One for myopia or hyperopia and the other for astigmatism 

Bifocal or Progressive contact lenses are lenses that have different zones for distance and near.  These are used for most people over the age of 40 who are also in need of reading glasses.

There are also custom lenses that are made for hard to fit eyes.  They are less common and are only used for special situations such as correcting irregular shaped corneas.  A condition known as keratoconus.  

written by Dr. K.Onu

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