Novel Device Could Represent New Endpoint in Clinical Trials for Visual Function

AUGUST 14, 2017
Thomas Castles
John B Miller, MDResearchers have built a novel device that uses an algorithm to analyze the visual limitations that follow retinal detachment repair, representing a potentially invaluable new endpoint for visual function in clinical trials.

According to John B Miller, MD (pictured), Director of Retinal Imaging at Massachusetts Eye and Ear, the device is necessary because everyday visual acuity tests don’t always tell the whole story about a patient’s reported quality of vision.

“You can have a patient with anatomic success and what you’d classically define as ‘visual acuity success,’ but that patient can still be frustrated with their vision,” Miller said at the annual meeting of the American Society of Retina Specialists (ASRS) in Boston. “What ways can we better quantify this? What measures could we have to help with demonstrating a significant improvement as we look at future clinical trials?”

To address those questions, Miller and colleagues used the Sentio Platform from Adaptive Sensory Technology in San Diego, CA – a computer adaptive, quick contrast sensitivity function test.

“It uses a hand-held tablet that your technician can use to provide contrast queries for the patient on a large monitor at 3 meters,” he said.

To test the device, Miller and colleagues conducted a prospective, observational multi-center IRB-approved case series that enrolled patients with mac-off rhegmatogenous retinal detachments between December 2016 and January 2017. They used the Sentio Platform to perform quick contrast sensitivity function (qCSF) testing in each eye in each patient.

The qCSF method used computerized, Bayesian, adaptive testing to track changes in a patient’s contrast sensitivity across spatial frequency to calculate an area under the curve (AUC). Contrast sensitivity was compared to previous data for age-matched controls, represented by calculating a Z-score (AUC-AgeMean)/Age Standard Deviation.

Patients had a mean visual acuity of 20/30, and their mean AUC was 0.83 in retinal detachment versus 1.27 in age-matched controls, which was statistically significant. The Z score for all retinal detachment patients on average was -1.99, or 2 standard deviations.

“It’s important to know that 9 of our patients had best corrected visual acuity of 20/30 or greater. And when we took a look at what we would typically classify as high visual acuity patients, we still found a statistically significant difference, with a Z-score of -1.08,” Miller said. “This corresponded to a greater than 1 standard deviation difference in our contrast function in what we would typically classify as highly functioning patients.”

Miller called the new device and testing approach an efficient, user-friendly, smart algorithm that can measure contrast function curves.

“We will be doing additional work to validate this technique, but we think it could represent an invaluable new endpoint for visual function in clinical trials, as we examine diseases where there really isn’t a big difference in visual acuity, but patients are still frustrated with their vision,” he said.

While the device is not currently approved by the US Food and Drug Administration (FDA), it is already in use in several retinopathies in the US, Miller added.

“Our goal is to do a larger prospective trial and incorporate some more patient-centric questions,” he said. “We’ve had the device built for under a year – probably about 6 or 8 months – so we haven’t done a lot of repeat testing. That’s certainly something we’ll be working on.”

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