Written on Mar 5, 2009 at 10:15 PM by LASIK Guider


Contact lenses (also known as contacts) are very thin lenses, placed directly on the cornea to correct vision. Most people, who use to correct their vision, would be able to replace it by contact lenses. Others prefer to have their vision permanently corrected by refractive surgery procedures such as .

How Contact lenses work:

Contact Lens Insertion

When placed on the , a contact lens floats on the tear layer covering the cornea and corrects vision by replacing the anterior (front) surface of the cornea, which is the .

Contact lenses can correct various types of refractive errors such as , and . The goal of these corrective contact lenses is to adjust the received image, allowing the eye to focus a sharp image on the retina at the back of the eye.

Advantages and Disadvantages of Contact Lenses:

Persons who do not wish to wear eyeglasses most frequently prefer contact lenses for many reasons. Contacts provide better peripheral vision devoid of obstacles such as the . This is especially significant in driving and in sports, where you need to see as much around you as possible.

Contact lenses also don not become misty easily in rain, snow or dust. Skin irritation and discomfort caused by the heavy weight of glasses is absent in contacts, so it is preferred especially in persons with high degrees of refractive errors, requiring thick corrective lenses in their glasses. Concerning your appearance, contacts correct vision without changing your look.

Contact lenses Case

On the other hand, contacts require regular maintenance by cleaning and disinfection; in addition to special care when they are inserted or removed. Another disadvantage of contacts is a possibility of eye infections from unclean lenses or bad hygiene during insertion and removal. Occasionally, correction of vision by contacts is not possible in persons suffering from severe eye allergy or frequent eye infections.

Types of Contact lenses

  • Hard Contact lenses have fixed shape and are made from PMMA( Polymethyl Methacrylate) which is not oxygen permeable. These lenses are rarely used nowadays.
  • Rigid Gas Permeable lenses (RGP) are made from rigid material and contain no water. These lenses allow oxygen to pass through it to the cornea. This makes RGP lenses more comfortable than the ordinary hard contact lenses.
  • Soft Contact lenses are flexible lenses that can be folded. These lenses are made from water-containing plastics which permit oxygen to pass through to the cornea.

    Water content in this type of lenses ranges from 30% to 80%, the higher the water content the longer the period it can be worn.

Designs of Contact Lenses:

  • Spherical contact lenses are the typical having anterior and posterior spherical surfaces and can be used to correct nearsightedness or farsightedness.
  • Toric contact lenses used to correct astigmatism.
  • Bifocal contact lenses provide both near and distance vision correction, which is required in .

Uses of Contact Lenses:

Colored Contact Lens
  • Optical uses: corrective contact lenses are used to correct refractive vision defects such as myopia, hyperopia and astigmatism.
  • Therapeutic uses: contacts can be used in treatment of many eye diseases, especially to provide protection and help in healing of the cornea.
  • Cosmetic uses : cosmetic contact lenses are available in many colors to change or improve the look of the eye. These lenses may also correct various types of including myopia, hyperopia and astigmatism.

Contact Lens Wearing Time and Replacement Schedule:

  • Daily wear contacts are designed to be removed from the eye at bedtime.
  • Extended wear contact lenses can be worn on average for up to a weak during waking and sleep hours without removal and cleaning.
  • Traditional contact lenses should be replaced by another pair every year.
  • Disposable (planned replacement) contact lenses can be replaced on daily, weekly, biweekly, monthly basis.

The full series of LASIK Vision Correction Explained tutorials are , , , ,, , , , and .


Youreyesite May 19, 2009 at 6:32 PM  

The contact lens case is often a harbor for bacteria and as such, should be replaced regularly or cleaned. Cleaning of a lens case involves briefly placing the case in boiling water after having manually cleaned the case. If you have a spare pair of lenses in your medicine cabinet, try to replace the solution and clean the case every two weeks. You may purchase new cases for pennies and often your doctor will provide you with free, sterile new cases if you ask.

LASIK Guider May 20, 2009 at 3:55 PM  

I agree with you that lens cases must be cleaned regularly. However i prefer replacing old lens case with a newer one on regular bases and I usually offer them for free to my patients.

cheapcontactlenses July 26, 2009 at 2:49 PM  

I find contact lenses a revolutionary invention. Especially because they are cheap, they are for sure a better option than glasses.

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