What Are Intraocular Lens Implants (IOL)?

Reviewed by: Jason Jacobs, M.D. and Leslie Doctor, M.D.

Intraocular lenses, or IOLs as they are more commonly known, are artificial lenses that are used to replace natural lenses that have become clouded with cataracts. They can also be used as a solution for people who suffer from presbyopia, a condition in which the lens becomes less flexible, thus losing its ability to focus on near objects.  Before the U.S. Food and Drug Administration approved the use of intraocular lenses in 1981, patients who had cataract surgery were forced to wear thick eyeglasses or contact lenses to improve their vision. Early monofocal IOLs were generally used to correct problems with distance vision, leaving patients to rely on glasses or contacts for near vision.

Monofocal vs. Multifocal IOLs

Traditional or monofocal IOLs can only offer patients improvement at one distance (intermediate, far, or near). Many Cataract Surgeons and eye centers offer multifocal implants to help our presbyopia and cataract surgery patients see more clearly at a range of distances. They use this technology to replace the eye’s natural lens with a new, artificial lens that can help restore visual clarity to near, intermediate and distance vision.

Cataracts, Astigmatism Toric IOLs

If you have astigmatism you may still experience blurred and distorted vision after traditional cataract surgery because a monofocal IOL cannot correct astigmatism. To achieve quality distance vision with a traditional IOL you may still require glasses, contact lens or further surgery. If freedom from glasses for distance vision is important to you, you now have a better option.  The unique design of a toric IOL makes it possible to reduce or eliminate astigmatism and significantly improve uncorrected distance vision.  Toric IOLs provide significantly improved distance vision and may reduce the need for corrective lenses compared to a traditional monofocal IOL.

Spherical Aberration and Cataracts

It's a little-known fact that, in spite of all the advances in eye care technology today, even healthy eyes still contain some imperfections called higher order aberrations. One type of higher order aberration common to cataract patients is spherical aberrations, which can lead to a gradual reduction in vision acuity and function. An aberration is an irregularity in the shape of the eye's refractive surface that can distort vision. As you get older, your eyes’ lenses get thicker and rounder, causing image quality to deteriorate. Spherical aberrations are generally associated with:

  • Blurriness
  • Halos
  • Loss of contrast
  • Poor night vision

Cataract surgeons can implant a lens designed to reduce spherical aberrations, increase contrast sensitivity, and improve functional vision. Aspheric implants offer these advantages over traditional spherical lens implants: enhanced clarity, improved image quality, and filtered blue light for rich vibrant color.

The information that has been provided here is intended to give patients a basic understanding of Intraocular Lens Implants (IOL) and Cataract Surgery. It is possible that your individual experience might be different. None of the information provided here is meant to be a substitute for or replace your eye doctor's consultation nor does it replace the need for you to consult with your Cataract Surgeon about specific details of Cataract Surgery and Intraocular Lens (IOL) Implantation.

text size
cataracts, cataract, cataract surgery, cataract patients

AcrySof®ReSTOR® is a registered trademark of Alcon, Inc., ReZoom™ and Technis® are registered trademarks of
Abbott Medical Optics and Crystalens® is a registered trademark of Bausch & Lomb.