Reviewed by Paula Anne Newman-Casey, MD, MS
Ann Arbor, MI—As clinicians look for better ways of glaucoma screening for patients in remote areas of the world or those who cannot mobilize easily, accurate and portable equipment plays a huge role.
When ophthalmologists in a study graded optic nerve photographs taken with a portable non-mydriatic camera (Pictor, Volk) and a standard table-top mydriatic camera (Topcon), there was not a significant difference in the measurement of cup-to-disc size between cameras, said Paula Anne Newman-Casey, MD, MS.
In many parts of the developing world, it is difficult for people to travel to eye clinics for routine screening. This is especially the case in Nepal, where the study took place. To screen for cataracts, for instance, teams of eye-care providers will travel for days and hike for hours, or even a day, to reach remote villages.
“There’s a real need for portable equipment,” said Dr. Newman-Casey, assistant professor of ophthalmology and visual sciences, Kellogg Eye Center, University of Michigan, Ann Arbor.
However, in the rush for portable devices, there sometimes has been less of a focus on whether the device is of high enough quality to ensure good clinical outcomes.
The current study aimed to evaluate whether a new portable fundus camera that does not require dilation would produce reasonable enough photographs to allow ophthalmologists to accurately assess the cup-to-disc ratio compared with standard technologies.
Researchers did a cross-sectional study of 422 eyes from 211 new patients recruited from the glaucoma clinic at Kathmandu, Nepal’s Tilganga Institute of Ophthalmology.
First, a glaucoma specialist evaluated all subjects by performing a dilated fundus exam and standard automated perimetry to establish a glaucoma diagnosis.
“Fundus photographs were taken using both the handheld camera [Pictor] before dilation and a tabletop fundus camera [Topcon] after dilation for comparison,” Dr. Newman-Casey said.
Then, two masked glaucoma specialists graded the images for a cup-to-disc ratio. Overall, there was no significant difference in ophthalmologists’ cup-to-disc ratio grade between the portable and standard cameras.
However, glaucoma could not be accurately diagnosed based on fundus photographs alone, Dr. Newman-Casey said—a finding in-line with other published research.
“The Pictor had a sensitivity of 48.1% to 61.5% and specificity of 44.1% to 62.8% to remotely diagnose glaucoma when compared with the clinical examination,” the authors wrote in their abstract. “Similarly, the Topcon had a sensitivity of 47.5% to 53.9% and specificity of 55.6% to 64.2% when compared with clinical examination.”
Benefits outweigh challenges
Still, the overall results pleased researchers because they have found it reasonable to use portable camera to take fundus photographs as part of glaucoma screening in remote areas. The results are also positive because the camera does not require the time-consuming task of dilation.
Even physicians in the United States should take note of the results, Dr. Newman-Casey said, as portable screening could come in handy at hospitals or nursing homes.
There are some considerations with use of a portable fundus camera, Dr. Newman-Casey said. It takes some training to get to know how to use the camera, and continuous practice is required so images will be of the right quality.
“As the technology evolves, we hope that new solutions will become available that are easier to use,” she said.
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Paula Anne Newman-Casey, MD, MS
This article was adapted from Dr. Newman-Casey’s presentation at the 2016 meeting of the Association for Research in Vision and Ophthalmology. Dr. Newman-Casey did not indicate any proprietary interest in the subject matter.