Teleophthalmology increases detection of diabetic retinopathy in remote Canada

Nonmydriatic digital imaging cameras have been effective in diagnosing retinopathy in at-risk populations.

ByNicole Nader

Canadian health officials are attempting to address the backlog of undetected eye disease in the country’s aboriginal groups by supporting new efforts in telemedicine.

“At present, the major thrust of Canadian teleophthalmology is directed towards screening for diabetic retinopathy in remote First Nations settings and employing digital imaging techniques for the evaluation of this ocular complication,” said David Maberley, MD, FRCSC, MSc, of the British Columbia Center for Epidemiologic and International Ophthalmology. Dr. Maberley presented an overview of the current state and future direction of teleophthalmology in Canada during the first Canadian Ophthalmic Telemedicine Meeting.

“In the past three years, there has been a dramatic increase in the practice of teleophthalmology here in Canada,” Miguel N. Burnier Jr., MD, PhD, a professor of ophthalmology, pathology, medicine, anatomy and cell biology at McGill University in Montreal, told Ocular Surgery News.

Telemedicine – the exchange of medical information via electronic communications over a distance – can be used in every aspect of medicine, from diagnosis and treatment to education and research, Dr. Burnier said in a June 2003 editorial for the Canadian Journal of Ophthalmology. He noted how crucial images are for differential diagnoses.

According to the 2001 Canadian census, more than 1 million people comprised the aboriginal identity population in Canada and its provinces and territories. Dr. Burnier said that, in this population, one in 10 people have diabetes that can lead to retinopathy and, ultimately, blindness.

“Fortunately, timely treatment can decrease rates of blindness and visual impairment by 90%,” he said. “Using telemedicine as a screening tool for ocular complications has proven to be a highly efficient method to detect early signs of retinopathy,” he said.

Teleophthalmology programs

In teleophthalmology, health care workers use digital cameras to capture retinal images of people in remote locations who have little access to medical care. Through e-mail or a computer database system, images are sent to trained interpreters, usually ophthalmologists, who can read the images and provide a preliminary diagnosis.

Such programs are currently being implemented throughout Canada in the provinces of British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec and Nova Scotia. However, these programs are in varying stages of development.

A program in the Northwest Territories and Alberta trains paramedical workers from the Stanton Regional Health Board in Yellowknife, Northwest Territories, to conduct annual retinal screening tests with a portable photoscreener, Dr. Burnier said. “Technicians visit remote communities on a rotating basis to conduct the tests and send the information back to Alberta for diagnosis,” he said.

These programs seek to break down language and cultural barriers by enlisting the services of native peoples, he said. While the programs are helpful, some health officials say that national guidelines still need to be in place, so that all people receive a universal level of care.

“Efforts should be made to ensure that a degree of internal validation, evaluation and documentation are part of each telemedicine protocol,” Dr. Maberley said. “These guiding principles may be of general use to organizations interested in implementing or refining teleophthalmology practices.”

Digital imaging useful

In teleophthalmological examinations, recent studies have shown that nonmydriatic digital cameras may be the most efficient and cost-effective on-the-go tools for recognizing patients with retinal conditions.

According to a study that appeared last year in the Canadian Journal of Ophthalmology, digital cameras may be as effective as traditional methods of screening. Marie Carole Boucher, MD, and colleagues analyzed the sensitivity and specificity of the Topcon CRW6 nonmydriatic digital camera. When referring patients with a threshold of mild retinopathy, the Topcon digital camera showed 97.7% sensitivity and 84% specificity when compared with the gold standard of seven standard stereoscopic visual fields (7SF).

Ninety-eight patients with type 1 and type 2 diabetes were assessed for diabetic retinopathy with both the Topcon nonmydriatic digital camera and 7SF in the study. The level of retinopathy was graded blindly multiple times and weighted against guidelines from the Early Treatment Diabetic Retinopathy Study.

Outcomes showed a “substantial agreement” between the grading of retinopathy with the Topcon nonmydriatic digital camera and 7SF.

The study’s authors concluded that the “results suggest that two-field nonmydriatic camera imaging is a safe screening strategy that may identify the patients with diabetes most in need of ophthalmic care.”

Effective screening test

Table A study by Johanna Choremis, MD, and David R. Chow, MD, which appeared in the December 2003 issue of the Canadian Journal of Ophthalmology, also found nonmydriatic digital imaging to be an effective screening tool.

Drs. Choremis and Chow analyzed the retinal photographs of 415 diabetic patients (830 eyes) for signs of retinopathy. Patients attending a Montreal university-affiliated hospital’s outpatient endocrinology department were screened with a Canon CR6-45NM nonmydriatic 45 camera, between September 2000 and January 2001.

Two photographs were taken of each patient’s retina. Additionally, patients were asked to complete questionnaires detailing their diabetes history, severity of disease, associated eye conditions and laser surgery history. The questionnaire and photographic images were sent to an in-office retinal specialist through the hospital’s intranet system.

The attending specialist viewed the images and subsequently sent back a progress report, grading the level of diabetic retinopathy (if any), the presence or absence of retinal hard exudates and the quality of images received. Recommendations for follow-up visits were transmitted back to the screening site.

Ten percent of patients were referred to an ophthalmologist due to their diagnosis of retinopathy, based on image interpretation. Eight-four percent of patients had type 2 diabetes. Nonproliferative diabetic retinopathy was found in 14.1% of patients (117 eyes), and proliferative diabetic retinopathy was found in 1.5% of patients (15 eyes).

Macular hard exudates were found in 6% of patients (50 eyes), and unexpected findings of epiretinal membranes, macular holes, bilateral cotton-wool spots and central retinal vein occlusion were found in nearly 1% of eyes (7 patients).

Thirty-five percent of screened images obtained were judged unreadable due to poor image resolution. However, over time, the study authors said that image quality improved significantly (P < .01).

Despite these technical complications, the authors concluded that the study was successful.

“The system was favorable, allowing us to screen large numbers of patients in a cost-effective, reliable manner,” the study concluded.

Future of teleophthalmology

According to Drs. Burnier and Maberley, teleophthalmology may successfully branch out beyond screening for diabetic retinopathy to include other eye diseases, like glaucoma. Future considerations for teleophthalmology may include real-time video conferencing, visual electrodiagnosis, video transmission and transmission of full-color fundus photographs, Dr. Burnier said.

“This technology enables specialists from all over the world to assess a case while simultaneously discussing possible treatment plans,” Dr. Burnier said. “This is especially useful in cases of diagnostic ambiguity. Several specialists worldwide can review images from diagnostic dilemmas in ophthalmology.”

Ultimately, what Dr. Burnier calls the inevitable increase of telemedicine in ophthalmology will come to benefit a large number of patients, despite their geographic, social and economic status.

For Your Information:

Miguel N. Burnier Jr., MD, PhD, can be reached at McGill University, Royal Victoria Hospital, Room H7-53, 687 Pine Ave. W., H3Y181, Montreal, Quebec, Canada; +1-514-843-1544.

David Maberley, MD, FRCSC, MSc, can be reached at the British Columbia Center for Epidemiologic and International Ophthalmology, Section C, 2550 Willow St., Vancouver, BC V5Z 3N9; +1-604-875-4599; fax: +1-604-875-4699.

References:

Choremis J, Chow DR. Use of telemedicine in screening for diabetic retinopathy. Can J Ophthalmol. 2003;38(7):575-579.

Boucher MC, Gresset JA, et al. Effectiveness and safety of screening for diabetic retinopathy with two nonmydriatic digital images compared with the seven standard stereoscopic photographic fields. Can J Ophthalmol. 2003;38(7):557-568.

Nicole Nader is an OSN Staff Writer who covers ophthalmology in pediatrics, strabismus and neuro-ophthalmology, in addition to cataract and refractive surgery.