Pupil dilation enhances screening for diabetic retinopathy by endocrinologists

Pupil dilation enhanced the quality of retinal images in a study, improving the diagnostic performance.

Issue: February 1, 2006

ByJared Schultz

Pharmacological pupil dilation improved the quality of retinal images for assessing the severity of diabetic retinopathy, according to researchers in France. The improvement in image quality helped increase the diagnostic accuracy of endocrinologists, the researchers found.

With a shrinking number of ophthalmologists and an increasing number of patients with diabetes in France, Nilanjana Deb-Joardar, MD, FRCS, and colleagues at Bellevue Hospital in Saint-Étienne wanted to establish a screening method that could be used by trained endocrinologists to detect diabetic retinopathy.

“Retinopathy screening has been the prerogative of ophthalmologists, but considering the rapid decline in their numbers in recent years, screening should be delegated to another type of medical professional, such as endocrinologists,” the researchers said in a report on their study in the American Journal of Ophthalmology.

According to Philippe Gain, MD, PhD, the corresponding author of the study, most diabetic retinopathy screening in France is done without dilation, “mostly as a matter of principle, rather than convenience or quality criteria.”

In an e-mail to Ocular Surgery News, Dr. Gain said some specialty screening centers have been established in France, “but these numbers are yet small compared to the requirement, and the procedure is time-consuming.”

“We are trying to change this by assuring a rapid and good quality service that can be employed at the hospital or even primary care level to ensure long-term feasibility and wider coverage.”

Because the optometric profession does not exist in France, and orthoptists and other paramedical personnel are not allowed to perform screening, Dr. Gain and others are interested in bringing allied medical specialists such as endocrinologists into the screening process for diabetic retinopathy.

Drs Deb-Joardar and Gain and colleagues conducted a pilot study to assess the effects of pupillary dilation on image quality and certitude of screening for diabetic retinopathy by trained endocrinologists using a nonmydriatic camera.

The study included 150 patients with type 1, type 2 or gestational diabetes attending a photographic screening clinic. The patients underwent 45° five-field digital retinal imaging with a nonmydriatic digital camera, and mosaics were constructed.

The mean age of the patients was 59 years, and the mean duration of diabetes was 15 years.

The researchers took images first through dark-adapted pupils and then after a single application of tropicamide 1%. They acquired 600 sets of images (two eyes of each patient, undilated and dilated), which were then graded by two endocrinologists and two ophthalmologists independently in a masked manner. The consensus opinion of the two ophthalmologists on the dilated images served as the gold standard.

The study evaluated image quality as well as the certitude of detecting and grading retinopathy.

“Considerable improvement in the detection of any retinopathy, sight-threatening retinopathy, and maculopathy was noticed after dilation for all observers,” the researchers said.

Better images, better detection

For individual eyes and both eyes, the undilated photography resulted in 93% gradable images compared with dilated photography, which resulted in 99% gradable images (P < .001).

There was a significant improvement in the quality of the images taken after pharmacological mydriasis, with an average increase in the number of sets with good images from seven using natural mydriasis, to 160 out of 300 eyes for all the observers.

There was also a significant improvement in the mosaic quality after dilation, with the number of good mosaics increasing from 99 of 300 eyes to 233, and the number of ungradable mosaics decreasing from 21 of 300 eyes to three.

With the increase in quality images came an increase in the number of cases diagnosed with certainty, according to the researchers, from 153 to 252 (P < .001) out of 300 eyes. Images graded with certainty increased from 173 to 277 (P < .001).

“The certitude of detecting and grading retinopathy by newly trained graders significantly increased after dilation, reflecting their increased confidence in the dilated condition, an essential prerequisite for delegation,” the researchers said.

Faster screening

Using drops to achieve mydriasis reduced the average screening time by 15 minutes, the same amount of time it would take to induce spontaneous mydriasis in the dark and to obtain redilation between image captures, the investigators said.

The amount of time saved by delegating screening would allow physicians to better meet the needs of the increasing numbers of diabetic patients, they noted.

“Pharmacological dilation enabled faster image capture and could permit good-quality screening for up to three times as many patients in the future,” they said.

Screeners needed

According to the study authors, this is the first time endocrinologists in France have been involved in a study to assess their ability to screen for diabetic retinopathy with a nonmydriatic camera.

As the number of ophthalmologists in France is expected to decline due to a generally decreasing number of new physicians and an increasing percentage of aging ones, some ophthalmologists have been studying the feasibility of involving endocrinologists in the screening process for diabetic retinopathy, as it falls in their field of expertise.

For Your Information:

Philippe Gain, MD, PhD, is the corresponding author for this study. He can be reached at Service d’Ophtalmologie (pavillon 50A), CHRU de Bellevue, 25 Boulevard Pasteur, F 42055 Saint-Etienne Cedex 2, France; 33-04-77-42-14-00; fax: 33-04-77-12-09-95; e-mail: philippe.gain@univ-st-etienne.fr.

Jared Schultz is an OSN Staff Writer who covers all aspects of ophthalmology. He focuses geographically on Europe and the Asia-Pacific region.