Telemedicine helpful tool for assessing diabetic retinopathy

Baltimore-The problem of an increasingly large population of patients with diabetes has spawned a novel and sometimes controversial approach to management: consultation via telemedicine assessment. Ingrid Zimmer-Galler, MD, discussed this high-tech approach to care at the recent Current Concepts in Ophthalmology meeting.

"There are well-established guidelines for regular eye examinations and the benefits of screening eye examinations have been well proven. Despite this, about 50% of patients with diabetes do not follow these guidelines. For this reason, diabetes remains the leading cause of vision loss in adults of working age in the United States despite tremendous efforts on the local, state, and national levels to the contrary," Dr. Zimmer-Galler stated at the meeting sponsored by the Johns Hopkins University School of Medicine, Baltimore, and Ophthalmology Times.

Diabetic retinopathy, she explained, is an ideal model for telemedicine initiatives with the use of remote digital retinal imaging. National and international support has been seen for the use of telemedicine assessment of diabetic retinopathy.

She explained that the ETDRS 30° stereo seven-field color 35-mm fundus photographs are the gold standard for evaluating diabetic retinopathy. Imaging used for diabetic retinopathy screening programs should be validated against and compare favorably with ETDRS stereo color photographs, she advised.

Validation levels

Dr. Zimmer-Galler described four validation levels. The first and simplest, category 1, separated patients with no or very mild non-proliferative diabetic retinopathy-that is an ETDRS level of 20 or below-from those with more severe disease. Patients with any diabetic retinopathy are referred.

Category 2 is more stringent and can determine if sight-threatening diabetic retinopathy is present (an ETDRS level of 53 or worse)-that is evidence of macular edema, proliferative diabetic retinopathy, and severe non-proliferative diabetic retinopathy. Patients with sight-threatening diabetic retinopathy usually require prompt laser or other treatment.

Category 3 can more specifically identify the ETDRS-defined levels of non-proliferative diabetic retinopathy, proliferative retinopathy, and macular edema. A system such as this, she noted, could actually be used to manage disease.

Category 4 is a system that is equal to or better than the ETDRS photographs in its ability to identify lesions of diabetic retinopathy to determine levels of diabetic retinopathy and macular edema. Such a system could theoretically replace ETDRS photographs in clinical or research settings.

Unreadable images

An important consideration in any program is that if the program personnel cannot obtain images or obtain unreadable images, this should be considered a positive finding and the patient should be referred for ophthalmic evaluation, according to Dr. Zimmer-Galler.

She cited a technology assessment meta-analysis of 32 articles (three of which were level I studies and four were level II studies) published in Ophthalmology (Williams GA, Scott IU, Haller JA, et al. Single-field fundus photography for diabetic retinopathy screening. 2004;111:1055-1062) that evaluate single-field fundus photography as a screening tool to identify diabetic retinopathy.

Evidence from three level 1 studies indicated that single-field fundus photography is a tool that can detect vision-threatening retinopathy, with sensitivity ranging from 61% to 90% and specificity ranging from 85% to 97% when compared with stereo photographs. When compared with dilated ophthalmoscopy performed by an ophthalmologist, the study found that single-field fundus photography has a sensitivity ranging from 38% to 100% and specificity ranging from 75% to 100%. Single-field fundus photography cannot substitute for a comprehensive ophthalmic examination but, based on these results, can be used successfully to screen for diabetic retinopathy.

The Wilmer Eye Institute uses the DigiScope system (Eli Lilly and Co. and EyeTel Imaging), an Internet-based digital retinal camera, to screen for diabetic retinopathy in a primary-care setting. The images, obtained in the primary-care physician's office, are sent to a reading center and the data are reviewed by trained readers who are supervised by a retina specialist.

Thus far, more than 22,000 patients have been imaged, none of whom had been examined by an ophthalmologist within the previous 12 months.