Remote screening can help detect diabetic eye disease

In the article, "Utility of Hard Exudates for the Screening of Macular Edema," using digital photographs of the eye taken at the doctor's office or clinic, eye specialists can reliably detect "hard exudates" -- a key early sign of diabetes-related macular edema, reports the new research by Jorge A. Cuadros, OD, PhD, of UC Berkeley School of Optometry and colleagues. "This study offers impressive support for the implementation of remote screening images for patients with diabetes, who are not being seen by eye specialists like optometrists and ophthalmologists," comments Anthony Adams, OD, PhD, Editor-in-Chief of Optometry and Vision Science.

Remote Detection of Hard Exudates in Eye Photographs

The researchers evaluated the use of the EyePACS "tele-ophthalmology" system to detect edema (wetness) resulting from leaky blood vessels in the retina at the back of the eye. This macular edema is one of the most serious vision-threatening changes in the eyes of people with diabetes.

"Edema that is detected close to the line of sight (straight-ahead vision) can and should be treated to slow or avoid any loss of vision," explains Dr Adams. "However about one-third of all people with diabetes don't realize they have diabetes and about 20 percent of those with recently diagnosed already have some changes in the blood vessels at the back of the eye."

Optometrists and ophthalmologists, with specialized training and instruments, can diagnose macular edema. However, these services aren't available or practical everywhere. In EyePACS and similar remote screening programs, primary care doctors or nurses take digital photographs of the eye, which are then sent for remote viewing and diagnosis by an optometrist or ophthalmologist.

One sign these specialists look for is small yellow "hard exudates" -- an indicator of current or very recent edema. In their study, Dr Cuadros and coauthors sought to determine whether hard exudates in clinic photographs are an accurate indicator of clinically significant macular edema in patients with diabetes.

Sensitive Screening Test for Diabetic Eye Disease

The study included 103 adults with type 2 diabetes, seen at a public health clinic, who were considered at high risk for macular edema. A special digital camera was used to take a magnified view of the interior of the eye, without the use of eye drops to dilate the pupil. The photos were sent over the Internet for review by eye specialists, who looked for hard exudates close to the line of sight as an indicator of clinically significant macular edema.

Within a few months, patients returned to the clinic for specialist examination, including dilation of the pupil and stereo views of the interior of the eye -- the standard test for diabetic eye disease. The dilated exams showed clinically significant macular edema in about 15 percent of patients.

Hard exudates detected on the digital photographs were an accurate indicator of macular edema. "The presence of hard exudates allowed correct detection of actual edema close to 90 percent of the time," says Dr Adams. "Just as important, the test was close to 80 percent accurate in correctly identifying when no edema was present." Thus the screening procedure had a sensitivity of 90 percent and specificity of 80 percent.

To prevent vision loss, it's important to identify and treat diabetic eye damage as early as possible. Remote screening tests have been developed to increase the number of diabetic patients screened for eye disease. That's especially important in groups without access to specialist vision care, like the public clinic patients evaluated in the new study. Dr Cuadros is inventor of the EyePACS system, which is used to screen nearly 36,000 patients each year at the UC Berkeley School of Optometry Digital Health Clinic.

Although further research is needed, the new results show that that remote screening -- and specifically the detection of hard exudates in nondilated eye photographs -- can accurately identify patients with diabetic eye disease. Dr Cuadros and coauthors conclude, "Low-cost and reliable methods of detecting clinically significant macular edema, such as the use of a hard exudate surrogate marker described here, are needed to meet the challenge of widespread screening for this vision-threatening condition."