Intraocular Lenses


What is an IOL and how does it work?

The clouding or opacification of the natural lens of the eye is called a cataract. An intraocular lens (IOL) replaces this opacified natural lens and is implanted at the time of cataract surgery. An IOL focuses light that comes into your eyes through the cornea and pupil onto the retina, which relays images through the optic nerve to the brain. Most IOLs are made of a flexible, foldable material and are about one-third of the size of a dime.

How will my doctor know which IOL is best for me?

Your IOL will contain the appropriate prescription, or lens power, to give you the best vision after cataract surgery, much like a prescription you would have for glasses. The appropriate IOL power is determined by measuring the curvature of your cornea and the length of your eye. The technology currently used to obtain these measurements has improved tremendously in recent years, increasing the precision of determining the IOL power. This gathered information is entered into an in-office computer programmed to calculate the IOL power specific to your eye and desired outcome.

What are the different types of IOLs available?

The type of IOL implanted will affect your dependency on glasses. Glasses may still be needed by some people for some activities. There are presbyopia-correcting IOLs available to increase spectacle independence after cataract surgery. In certain cases, cost may be a deciding factor for you if you have the option of selecting premium IOLs that may reduce your dependency on glasses.

The following are the different types of IOLs that are available:

Monofocal IOL: This is the most common IOL type implanted. A monofocal IOL, a singular focus lens, may be targeted to provide best vision at near or far distances without glasses. Most people who choose monofocal IOLs have their IOLs focused for distance vision and use reading glasses for near activities. On the other hand, a person whose IOLs are focused for near vision would need glasses to see distant objects clearly. Insurance covers monofocal IOLs.

Presbyopia-correcting IOLs: These newer IOL types may reduce or eliminate the need for glasses by expanding the range of clear vision for the patient.  There are three designs in this category: multifocal, accommodating and extended depth of focus (EDOF) IOLs. The multifocal IOL is designed with a series of focal zones or rings which allows images at a near and distance range to become in focus for the patient.  The design of the accommodating IOL allows the ciliary muscle to move the IOL forward with contraction, changing the focus much as it would with a natural lens, to focus both at near and distance vision. The EDOF IOL creates a single elongated focal point to extend the depth of focus for the patient. Each person’s success with these IOLs may vary and not patients are candidates for this IOLs. There are potential draw backs in vision with these IOLs. These presbyopia-correcting IOLs are not covered by insurance.

Toric IOL. This is a monofocal IOL with astigmatism correction built into the lens. Astigmatism distorts or blurs the ability to see both near and distant objects. The cornea of a person with astigmatism is not spherical in shape and requires more optical correction. People with significant degrees of astigmatism are usually very satisfied with the clarity of their vision with toric IOL implantation. The toric IOL is not covered by insurance. There are other alternatives to correcting corneal astigmatism, such as with glasses or contact lenses after surgery or with corneal surgery, which your OCB eye doctor can discuss with you.


OCB’s Cataract Team