Tablet-based tests putting detection of glaucoma at hand

An iPad-based quick contrast sensitivity test had similar sensitivity and specificity to frequency-doubling technology.

Reviewed by Brian J. Song, MD

Boston-Though telemedicine has gained acceptance in the evaluation of patients with diabetic retinopathy and retinopathy of prematurity, it has yet to establish a solid niche in glaucoma.

However, findings from a preliminary study suggest that portable visual function tests may be sufficiently accurate to play a role in glaucoma care, according to Brian J. Song, MD, instructor in ophthalmology, Massachusetts Eye and Ear Infirmary and Department of Ophthalmology, Harvard Medical School.

Dr. Song and colleagues evaluated the performance of several iPad-based visual function tests, comparing them with frequency-doubling technology (FDT).

“None of the tests alone are sufficient for diagnosing glaucoma, but some of them have a high enough sensitivity or specificity that they could potentially be used in addition to other tests to improve the accuracy of the evaluation if you were to move to a complete telemedicine model the way certain other countries are starting to move,” Dr. Song said.

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Eighty-two eyes of 82 patients with early manifest glaucoma and 38 eyes of 38 age-matched controls were evaluated at the Massachusetts Eye and Ear Infirmary. They underwent the same four tests in random order: FDT, the visualFields easy iPad app, blue arc entoptic phenomenon testing, and quick contrast sensitivity function (QCSF) testing.

Sensitivity, specificity, and positive and negative predictive values were calculated for all tests. Receiver operating characteristic (ROC) curves were plotted for the area under the log contrast sensitivity function (AULCSF) as well as the contrast sensitivity function acuity (CSF Acuity) of the QCSF test.

Though the FDT is not iPad-based, it was included in the study since it is well validated and commonly used as a portable test in many glaucoma screening programs, Dr. Song said.

Analyzing findings

The results showed that the overall accuracy of the iPad-based QCSF test were similar to that of the FDT for the detection of early manifest glaucoma. FDT sensitivity was 0.83 (0.72-0.90, and the specificity was 0.66 (0.49-0.80). For the QCSF, measurements of CSF acuity results were: sensitivity 0.64 (0.55-0.75) and specificity 0.81 (0.68-0.94); sensitivity and specificity for AULCSF were 0.72 (0.62-0.81) and 0.73 (0.59-0.87), respectively.

“These are preliminary results, but it seems like the contrast sensitivity test may be the best of the ones we looked at, and it also has the advantage of being fixation independent,” said Dr. Song, whose research focus is development and validation of glaucoma evaluation in diabetes telemedicine programs.

“What we want to do is be able to test function without necessarily having patients come into a specialty care clinic where they have to take the test with an expensive machine,” Dr. Song said. “If they could do something like that at home, it would save time and those results could then be forwarded to a specialist who could review the results and add that information to a set of images.”

That may improve the accuracy of the diagnosis or evaluation, and people might even be able to monitor or screen themselves at home, he added.

Further benefits

With an accurate computer-based or tablet-based test, patients would not have to buy specialized equipment in order to obtain helpful functional information or share it with their providers. Integrating such a test would not add significant costs or time to a standard telemedicine evaluation and could add value.

It could also benefit patients who face obstacles such as a long travel time to a specialty clinic or difficulty obtaining an appointment at an overbooked office.

Forwarding the results of a visual function test completed at home, in conjunction with other steps such as having IOP measured locally, might be a way to offset the need for at least some follow-up visits to a glaucoma clinic, especially in patients with relatively stable disease, Dr. Song said.

Brian J. Song, MD

E: Brian_Song@MEEI.HARVARD.EDU

This article was adapted from a presentation given at the 2016 meeting of the Association for Research in Vision and Ophthalmology by co-author Meredith Kim, a student at George Washington University, School of Medicine, Washington, DC.