Purpose of Cataract Surgery

Cataract surgery involves removing the lens of your eye and replacing it with a clear, artificial lens. A person usually undergoes cataract surgery when their visual symptoms (e.g., blurry vision or seeing colors as less vivid) interfere with their daily routine. Even though cataract surgery is a common and safe procedure, you will need to undergo several eye tests in order to prepare for it.

Cataract surgery
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Diagnosis Related to Cataract Surgery

Cataracts, while generally associated with aging, may also develop as a result of an eye injury, taking certain medications (e.g., prednisone), spending a lot of time in the sun, or having an underlying medical condition like diabetes. Congenital cataracts can be present at birth.

The only way to definitively treat a cataract is through cataract surgery, which is performed by an eye specialist called an ophthalmologist. There is, however, no set timeline for undergoing the surgery and no specific criteria for determining if a person is a candidate.

The main indication for cataract surgery is a person's vision symptoms negatively impacting their daily functioning (e.g., problems driving, reading, or working) and/or quality of life.

This means that if your vision is still good and you can function and live well, you may not need surgery right away. Instead, before opting for surgery, you may try these options:

Another possible, albeit less common indication for undergoing cataract surgery is the presence of a coexisting eye disease. In some cases, cataracts may impair a healthcare provider's ability to evaluate and treat other eye conditions like diabetic retinopathy or macular degeneration. Removing the cataract may be necessary to move forward with managing the other eye problem.

Tests and Labs

Before cataract surgery, your healthcare provider will want to carefully evaluate your visual function, look for coexisting eye diseases, and determine the refractive (i.e., focusing) power for your artificial lens, which is called an intraocular lens or IOL.

You can expect to undergo some or all of the following tests, depending on your case.

  • Visual acuity and refraction test: Visual acuity is a measure of how well you can see. It is measured by looking at an eye chart 20 feet away. A refraction test involves you looking at the same eye chart while looking through a special instrument called a phoropter. By switching through different lenses, the test determines the degree of refractive error you have from your cataract.
  • Slit lamp exam: A slit lamp exam is a microscopic examination of the lens of the eye while dilated. This test is used to grade the severity of the cataract.
  • Biometric test: This test takes detailed measurements of your eye, such as the exact position of the lens and the lens thickness. The results of this test help your eye healthcare provider determine the refractive power of the artificial lens needed to replace your cloudy lens.
  • Ultrasound: This quick and painless test uses sound waves to provide a picture of your lens, eye size, and eye shape. It helps determine the exact width of the artificial lens you will need.
  • Optical coherence tomography (OCT): An OCT uses light waves to produce detailed pictures of your retina. In addition to providing useful information about retinal thickness, OCT is also used to detect early signs of glaucoma.
  • Optical Quality Analysis System (OQAS): This test measures vision quality objectively. A special light is imaged on your retina and then analyzed.
  • Corneal mapping: This advanced tool provides a 3D model of the front of your eye, where structures like your cornea, lens, and iris are located. It can help healthcare providers determine how much of your blurry vision is attributed to your lens versus your cornea.
  • Potential Acuity Meter (PAM) test: This test provides information about whether cataract surgery is likely to improve vision in patients with coexisting eye diseases, such as macular degeneration. An eye chart is projected directly into the eye and onto the retina with a certain light, similar to a laser, that attempts to bypass the cataract itself. Vision measured is an estimate of how much vision may improve after cataract surgery is performed.

During these tests, your eyes will likely be dilated. This means that your pupil will increase in size in order to give the healthcare provider a better view of your lens. You may be sensitive to light for several hours afterward. It is best to have someone drive you home afterward.

Routine medical tests (e.g., electrocardiogram or laboratory tests) are not generally performed in people before undergoing cataract surgery, as they have not been found to improve the safety of the surgery.

Your eye surgeon will request that you visit your primary care healthcare provider prior to the surgery to rule out any possible complications and confirm that any health conditions you may have are well-managed.

A Word From Verywell

Undergoing cataract surgery requires a careful and thoughtful discussion between you and your ophthalmologist. In addition to discussing whether or not you are a good candidate for the procedure, be sure to review all the potential risks and complications in your case with your healthcare provider.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Boyd K. American Academy of Ophthalmology. What Are Cataracts?

  2. Boyd K. American Academy of Opthalmology: Cataract Surgery.

  3. American Optometric Association. Cataract.

  4. Khazaeni LM. Merck Manual. Professional Version. Cataract.

  5. Woodham's Eye Clinic. Preparing for Cataract Surgery: 5 Diagnostic Tests.

  6. Hwang JS, Lee YP, Bae SH, Kim HK, Yi K, Shin YJ. Utility of the Optical Quality Analysis System for Decision-Making in Cataract Surgery. BMC Ophthalmol. 2018 Sep 3;18(1):231. doi: 10.1186/s12886-018-0904-1

  7. Jacobs DS. Cataract in adults. Gardiner MF, ed. UpToDate. Waltham, MA: UpToDate.

  8. Turbert D. American Academy of Opthalmology: What Is Optical Coherence Tomography?

  9. Keay L, Lindsley K, Tielsch J, Katz J, Schein O. Routine preoperative medical testing for cataract surgery. Cochrane Database Syst Rev. 2019 Jan 8;1(1):CD007293. doi: 10.1002/14651858.CD007293.pub4

Additional Reading

By Troy Bedinghaus, OD
Troy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association.