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Retinal video recording a novel option for diabetic retinopathy screening

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Retinal videos are just as effective as standard still retinal images for detecting diabetic retinopathy, according to results of a comparative study of the two techniques.

In the journal Ophthalmology, the investigators say retinal video recording is a “novel alternative diabetic retinopathy screening technique that is easy to learn with minimal training by nonexperienced personnel,” which may increase screening rates, particularly in developing countries.

Dr. Daniel Ting, from the Lions Eye Institute, University of Western Australia in Nedlands and colleagues enrolled 100 patients who were 53 years old on average and had diabetes for 13.7 years. The patients’ mean glycosylated hemoglobin level was 8.0%.

Fundus images were captured using standard color retinal still photography using an FF450 Plus (Carl Zeiss, Inc) and retinal video using the EyeScan device (Ophthalmic Imaging System, Sacramento, CA). One of the investigators on the study, Dr. Yogesan Kanagasingam, invented the EyeScan device.

All participants also had a slit-lamp examination. All videos and still images were interpreted by two experienced ophthalmologists.

Compared with the gold standard slit-lamp examination, the sensitivity of video recording for detecting the presence of any diabetic retinopathy was 93% (for both viewers) and the specificity was 95% for one viewer and 99% for the other.

This closely matched the sensitivity of retinal photography (92% for both viewers) and specificity (97% for one viewer, 98% for the other viewer) for detection of any diabetic retinopathy.

“Both imaging methods had 100% sensitivity and specificity in detecting sight-threatening diabetic retinopathy,” the authors note.

Retinal video recording was also comparable to retinal photography in detecting signs of diabetic retinopathy such as microaneurysms, retinal hemorrhages, cotton wool spots, venous beading, and intraretinal microvascular abnormalities.

The technical failure rate for retinal video recording and retinal photography were 7.0% and 5.5%, respectively. Of the 15 failed retinal videos, 7 eyes had grade III nuclear sclerotic cataract, 2 eyes were from a darkly pigmented patient, and 6 eyes were intolerant to bright light.

In this study, the authors note, the retinal video recordings were obtained after retinal photography, which may have led to irritation or exhaustion of patients’ eyes during the retinal video recording process.

The 14 failed retinal photographs were the result of cataracts (5 eyes), blurriness of the images due to eye movement (4 eyes) and intolerance to bright flash (5 eyes).

The authors note that general practitioners, nurses, allied health workers or any volunteer could be trained to obtain retinal video recordings, which may increase the number of diabetic patients screened.

One disadvantage of retinal video (at the moment) is that the saved videos require a high storage capacity; 1 second of video takes up about 20 megabytes and the videos take at least 30 seconds.

The study also used a relatively expensive high-end computer with a 27-inch reading monitor to minimize any diagnostic errors. Further study is needed to evaluate more economical devices with small screens and lower screen resolution.

More research is also needed to explore user friendliness, cost effectiveness, and clinical effectiveness in a community setting of diabetic retinopathy screening.