Monday, March 21, 2011

Types of Contact Lenses

Nowadays, you can easily buy contact lenses for aesthetic purposes. But originally, contact lenses are use only for people who want to improve their vision apart from using spectacles. There are different types of contact lenses for the latter reason. It is important to choose one that will give you comfort and not impair your vision more than usual.

1.       Hard contact lenses are made of polymethylmethacrylate (PMMA). PMMA is hydrophobic by nature causing limited permeability of oxygen. For this reason, this type of lenses is hardly use by people.
2.       Rigid gas-permeable (RGP) lenses have the features of hard contact lenses but oxygen is more permeable in this type. It delivers more oxygen to the cornea giving more comfort to the user. It is available in daily wear and extended wear versions. A surface active agent and enzymatic products are used to clean this type of lenses. It also needs to soak for 4 hours in a conditioning solution before using again.
3.       Soft lenses are comfortable and easier to remove compare to other contact lenses. The visual improvement with the use of these lenses is not significantly noted as that of the hard lenses or the rigid gas-permeable (RGP) lenses. This type of lenses should not be used when instilling topical ophthalmic products aside from rewetting solution.

Note: This topic shares a part in a comprehensive review for pharmacy in preparation for foreign pharmacy qualifying examination.


  1. We usually want to buy contact lenses for aesthetic purposes and necessity. Soft lenses have the facility that it is very easier to remove compared to other contact lenses.

  2. The compare to hard and RGP lenses the permeability oxygen level will be different. The first two lines may 100% correct.


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