Intraocular Lenses (P-IOLs)
Austin, Texas

An intraocular lens (IOL) is an artificial lens which can replace the eye’s natural lens. It is done in a fairly short outpatient procedure and vision will progressively improve over a few days.

The natural lens is suspended behind the iris (colored part of the eye). In a normal eye it is entirely transparent. The other transparent curved structure in the eye is the cornea, the clear front covering.

Functions of the Natural Lens

Allow light into the eye
Both the cornea and lens allow light into the eye where it focuses on the inside back surface. This is the retina which is filled with light-sensitive cells. They send the image data to the brain via the optic nerve.

Refract incoming light
For incoming light to focus on the retina and give clear vision, it must be bent (refracted) to a focus. The cornea does about 60% of this refraction and the lens does about 40%.

Accommodation
The lens is convex on both sides. Its curvature is controlled by tiny muscles which contract and relax to make the lens flatter or steeper. This is known as accommodation and it happens automatically when we switch focus from near to far objects.
Light coming from near objects needs to be refracted at sharper angles in order to focus on the retina. That requires the lens to steepen its curvature.
Light coming from far objects needs less refraction, so the lens becomes flatter.

The cornea also refracts light as it enters the eye, but has no ability to change its curvature. LASIK vision correction reshapes the cornea to change the way it refracts light.

Accommodative and Multifocal IOLs

These types of IOL are used to replace the eye’s natural lens when a problem with it is impairing vision.
Cataracts are small clumps of protein molecules – opacities which prevent some of the incoming light from reaching the retina. Since there is no way to remove cataracts from the lens, the lens is removed from the eye and replaced with an IOL.
Presbyopia is an age-related blurriness of near vision. The lens gradually becomes less able to steepen its curvature. There is so far no way to restore flexibility to an aging lens, so it can be removed and replaced with an IOL.

Since accommodation is lost when the natural lens is removed, modern IOLs use varying technologies to give clear vision at all distances. At Howerton Eye Clinic we offer three different IOLs to treat cataracts and presbyopia:
ReSTOR® -- a multifocal IOL
ReZoom® -- a different type of multifocal IOL

Please see our page on Multifocal Lenses and on cataract surgery for more information.

Phakic IOLs

This is a type of IOL which does not replace the natural lens, but is positioned next to it in the eye to treat severe nearsightedness. Please see our Visian™ and Verisyse™ page and the page on Phakic IOLs.

Toric IOLs

We offer toric IOLs to treat astigmatism. An astigmatic eye is not round like a ping pong ball, but oval like an egg. It has blurry vision at all distances. The oval shape can be in the cornea, in the lens, or in both. When it is in the cornea, LASIK or PRK can treat it. When it is in the lens, a toric IOL can be used to replace the lens. You can read more on our Toric IOL page.

Please call or email our Austin, Texas office if you would like to arrange a personal consultation. Both Dr. Berkowitz and Dr. Rhodes are highly experienced in using the different types of IOL and will be happy to answer your questions and make suggestions for you.

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