Intraocular Lenses | Williamson Eye Institute

Intraocular Lenses – IOLs

One of the most commonly performed eye surgical procedures is the insertion of an intraocular lens to treat cataracts. A cataract is the clouding of the lens inside the eye, which causes severe vision impairment. During cataract surgery, the eye’s natural lens is removed and replaced by an artificial lens called an intraocular lens (IOL). Before IOLs were available, cataract patients were forced to wear exceptionally thick eyeglasses after surgery. Now, with advanced technology, the use of IOLs has shown to significantly reduce the need for eyeglasses and become a well-known treatment for cataracts.

How Intraocular Lenses Are Made

While earlier forms of IOLs were made with polymethylmethacrylate (PMMA) or acrylic glass, advances in technology have introduced the use of silicon and acrylic, which are soft and foldable. These lenses can be inserted through a small incision and do not require stitches to heal.

Types of IOL Insertions

There are three kinds of IOL insertions:

  • Phakic – Phakia is the presence of the eye’s natural crystalline lenses. Phakic IOLs (PIOLs) are implanted without the removal of the crystalline. PIOLs can be either spheric or toric.
  • Aphakic – Aphakia is the absence of the eye’s natural crystalline caused by a previous surgery or trauma that occurred some time ago. Aphakic IOLs are implanted secondarily.
  • Pseudophakic  – Pseudophakic lenses are inserted as a replacement for the eye’s natural crystalline, which was removed during cataract surgery. This is the most commonly used IOL insertion.

IOL Varieties

Intraocular Lenses | Williamson Eye Institute | IOLsThe traditional monofocal IOL is the most commonly used IOL and has been for decades. Most patients choose to have their IOLs set for distance vision and use reading glasses for near activities. Some choose to have their IOLs set for intermediate vision by having one eye focused for distance and the other focused for near activities; this is referred to as “monovision.” The brain synthesizes the information from both eyes for intermediate distances. However, vision may not be as sharp.

While conventional monofocal IOLs are focused for distance vision and have a fixed power, the disadvantage is that many still have to use reading glasses for near vision tasks. However, advances in technology have brought about more accommodating IOLs known as premium IOLs. Aspheric and toric IOLs, unlike traditional IOLs, are designed to reduce the need for reading glasses.

  • Aspheric IOLs – The eye’s natural lens varies in curvature, making it aspherical.  The traditional shape of IOLs is spherical and doesn’t match the shape of the eye, which can impact vision quality. Aspheric IOLs are designed to match the shape of the eye closely, which provides sharper vision. One type of Aspheric IOL is the AcrySof ReSTOR IOL, which is a multifocal IOL that can provide quality vision throughout the entire visual spectrum.
  • Toric IOLs – Toric lenses are designed to correct astigmatism and myopia. These lenses allow the surgeon to change the orientation of the lens while inside the eye to ensure that the astigmatism is properly corrected. The use of toric lenses can greatly reduce the need for an additional procedure after cataract surgery, such as LASIK and PRK, which are used to correct any residual astigmatism.
  • Crystalens –  Crystalens is another accommodating IOL that can treat both a person’s cataracts and presbyopia – loss of near and intermediate vision. Similar to the human eye, Crystalens uses the eye muscle to flex and accommodate in order to focus on objects in the environment at all distances.

Risks and Consultation

Intraocular Lenses | Williamson Eye Institute | IOLsThe procedure poses several risks associated with eye surgery. Risks include infection, loosening of the lens, lens rotation, inflammation and night time halos. However, studies have shown that the procedure is safer than traditional laser eye treatment.

As with any medical decision, always be sure to consult your doctor first. It is important to keep in mind that IOL implants are permanent. Your doctor can help you determine if surgery is right for you or if corrective lenses (eyeglasses or contacts) would fit your needs best.

The implantation of IOLs is a delicate procedure and should only be handled by experienced doctors who can provide exceptional eye care. If you have questions about this procedure and would would like to set up an appointment with one of our experienced doctors, please contact us.


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