Contrast sensitivity testing always beneficial in cataract work-up

Issue: July 2008

ByJena Passut

Surgery may have come a long way in terms of removing cataracts, but optometrists are well poised to look beyond a 20/30 reading on a chart to determine a patient’s true visual function before and after that surgery, according to three practitioners who spoke to Primary Care Optometry News.

These practitioners believe Snellen acuity and 20/20 charts are not where vision testing should end for cataract patients.

Robert P. Wooldridge

“It certainly does not simulate what the cataract patients experience when they walk outside of your office on a bright, sunny day or when there is snow on the ground or, worse yet, when they are driving at night and they have car lights coming at them,” Robert P. Wooldridge, OD, FAAO, told PCON in an interview. “The whole concept of contrast sensitivity, in general, is underutilized in both optometry and ophthalmology, and our two means of checking vision – Snellen acuity and visual fields – do not do a good job of measuring a patient’s functional vision, especially in the presence of early cataracts.”

Pre-surgery patients

David Stewart

David Stewart, OD, FAAO, uses contrast sensitivity testing as both a diagnostic and demonstration tool.

“As [cataracts] are progressing, a patient may not realize the degree of vision loss they are running into,” Dr. Stewart said in an interview. “With some of them, you would think from regular Snellen acuity that they are not losing much ground, but then you do the contrast sensitivity test and it really drops off dramatically. It shows us the degree of loss that patients typically deal with in their everyday environment.”

Dr. Stewart told PCON that the contrast sensitivity test can mark how the vision is worsening over time.

David G. Kirschen

David G. Kirschen, OD, PhD, FAAO, said doctors who treat cataract patients should not rely on a standard eye chart to determine how well a patient can see.

“A standard eye chart in a doctor’s office is made up of small letters on a high contrast background at anywhere between 95% and 100% contrast,” he explained. “The visual demands that are put on the patient in the real world are not 20/20 in size and they are not high contrast. They are what we call mid-spatial frequencies. Contrast sensitivity testing allows you to measure the effect that the cataract is having over a variety of sizes and contrasts.”

Administering the test

Because a contrast sensitivity test is fairly easy to administer, both Drs. Wooldridge and Stewart say they rely on their technicians to give the test. Dr. Kirschen, however, said he prefers to administer the test so he can see how the patient reads the chart.

Dr. Stewart said he likes all of his patients to get the test as a baseline during a first visit.

“From then on we would recheck if we are hearing symptomatic complaints or seeing any changes in the cataract status or Snellen acuity,” he said.

Billing for contrast sensitivity

The doctors said they are not able to bill for contrast sensitivity testing at this time. Instead, they provide the test as part of the general cataract evaluation.

“There should be [compensation] for contrast sensitivity testing to cover the cost of the instrument and time involved,” Dr. Wooldridge said. Still, even without compensation “it is definitely worthwhile and may be critical in the evaluation of some patients,” he added.

Post-cataract surgery patients

Contrast sensitivity testing also is beneficial in following a postoperative cataract patient, the practitioners said. The test would help look for macular edema as well as capsular opacification.

“If that would start to opacify, you would see a decline in the contrast sensitivity,” Dr. Stewart said. “In turn, we would be monitoring how much of a drop and how many symptomatic problems it is creating. That would help us determine, also, when we would send the patient back to the surgeon for a Nd:YAG laser capsulotomy treatment.”

Dr. Wooldridge added that the test would help do two things for a patient with capsular opacification. “It helps you to understand that the patient has a true and valid complaint,” he said. “And it helps to justify a procedure.”

Beyond cataracts

“We try to get the word out as best we can about contrast sensitivity testing,” Dr. Kirschen said. “If you ask a doctor to put a piece of equipment in their office and the only thing it’s good for is cataract testing, then they have to ask the question, “Do I have enough cataract patients in my office to justify getting this test?’”

Dr. Kirschen also uses the test on his sports vision patients.

“It seems to reflect more of how the patient performs in the real world than how they perform on the standard eye chart,” he said.

Dr. Wooldridge agreed. “Care of cataract patients is the easiest area to see the value of this technology,” he said. “However, papers have also been written showing that contrast sensitivity can be sensitive in detecting glaucoma, even when visual fields are normal, or optic neuritis, diabetic retinal disease and macular degeneration. It’s clinical value is not limited to the evaluation of patients with media opacities alone.”

For more information:

Robert P. Wooldridge, OD, FAAO, is director of the Eye Foundation of Utah. He can be reached at 201 East 5900 South, Salt Lake City, UT 84107; (801) 268-6408; fax: (801) 262-9216; e-mail: RPWOD@aol.com.

David Stewart, OD, FAAO, can be reached at 3351 Dayton Xenia, Beavercreek, OH 45432; fax: (937) 429-9022; e-mail: idoc73@msn.com.

David G. Kirschen, OD, PhD, FAAO, a private practitioner, is the chief of Binocular Vision and Orthoptic Services at the Jules Stein Eye Institute, David Geffen School of Medicine, UCLA. He is also a full professor of Basic and Visual Science and Optometry at the Southern California College of Optometry. Dr. Kirschen has been the team optometrist for the Los Angeles Dodgers and the Boston Red Sox for the last 16 seasons. He can be reached at 428 S. Brea Blvd., Brea, CA 92821; (714) 529-2470; fax: (866) 801-4739; e-mail: david1@kirschen.net; Web site: www.kirschen.net.