Teleophthalmology in Diabetic Retinopathy

Telescreening: Is It Accurate?

Since its inception, telescreening have been under the constant scrutiny of health care providers for its practical application. Comparisons with face to face clinical exam are inevitable. A number of photographic methods have been evaluated that allow images of the retina to be captured and then interpreted by expert readers. The gold standard method is the Early Treatment Diabetic Retinopathy Study (ETDRS) 7 mydriatic standard field 35 mm stereoscopic color photograph. ⁶ Digital fundus photography and nonmydriatic photography are more practical alternatives, having the advantage of faster and easier acquisition and transmission and storage of retinal images.

Moss et al ⁷ reported on an overall agreement of 85.7% when comparing retinopathy detection by ophthalmoscopy performed by skilled examiners to 7 standard field stereoscopic 30° fundus photography evaluated by trained health care workers. This agreement rises to nearly 98% when evaluated by a specialist. Analysis of the discordance showed that conventional ophthalmoscopy could miss up to 50% of microaneurysms. Delori et al ⁸ reported more accurate visualization and documentation of the structures of the ocular fundus when using monochromatic illumination (red-free green light), as compared to the white light used to obtain color photographs.

The efficacy of digital image acquisition, as compared to film-based acquisition, has been reported by several investigators. According to a report by the American Academy of Ophthalmology, ⁹ single-field fundus photography can serve as a screening tool for DR to identify patients with retinopathy for referral to an ophthalmologist.

In a study conducted by Raman et al ¹⁰ in India, the nonmydriatic technique of photography was found to have a sensitivity of 62.5% (95% CI 24-91) and a specificity of 98.7% (95% CI 93-99) when compared with indirect ophthalmoscope. The mydriatic technique of photography had a sensitivity of 70% (95% CI 35-93) and a specificity of 98% (95% CI 93-99) when compared with indirect ophthalmoscope. They concluded that by using 3 nonsimultaneous 45° field stereoscopic fundus images, an improvement in the sensitivity of the nonmydriatic technique could be expected.

Fransen et al ¹¹ published the results of a comparison of standard evaluations using film to the same fields captured and transmitted as digital images. They found that the sensitivity of digital photograph compared to film was 98.2%, and the specificity was 98.7%. Statistical analysis identified that the evaluation of film and digital images provided substantially equivalent results. When comparing high-resolution stereoscopic digital fundus photography to contact lens biomicroscopy, Rudnisky et al ¹² found a high level of agreement with regards to the detection of clinically significant macular edema in diabetic patients. Ahmed et al ¹³ concluded that nonmydriatic digital stereoscopic retinal imaging is a sensitive and specific method for the screening and diagnosis of DR that may help improve compliance with the standards of eye care for patients with diabetes

In a 2003 report, Scanlon et al ¹⁴ compared mydriatic and nonmydriatic photo screening programs using dilated slit lamp biomicroscopy as the reference standard. In the study of 3,611 patients, the sensitivity of mydriatic digital photography was 87.8%, the specificity was 86.1%, and the technical failure rate was 3.7%. Photography through an undilated pupil was found to provide a sensitivity of 86.0%, a specificity of 76.6%, and a technical failure rate of 19.7%. A 2011 meta-analysis revealed that variations in mydriatic status alone do not significantly influence sensitivity (odds ratio [OR]: 0.89) or specificity (OR: 0.94) of detecting DR.

Murgatroyd and colleagues ¹⁵ evaluated digital image screening with a nonmydriatic camera in 398 patients (794 eyes). Mydriasis was found to reduce the proportion of ungradable photographs from 26% to 5%. Sensitivity and specificity based on gradable photographs only, were similar for undilated single field (77% and 95%, respectively) and dilated images (81% and 92%, respectively). Since 64% of patients had gradable images, the authors suggest the possibility of targeted mydriasis or dilating only those patients who fail initial undilated photography.

A number of studies have reported on the agreement regarding the presence and stage of retinopathy based on ophthalmoscopy versus photography or standard film versus digital imaging. These studies found a high level of agreement between retinal examination and imaging. Several studies have suggested that retinal imaging through a dilated pupil was equivalent or superior to ophthalmic examination regarding the detection of diabetic retinal changes. Although evidence indicates that digital imaging without mydriasis leads to an increase in the proportion of ungradable photographs, practice guidelines and clinical input support the use of both dilated and undilated retinal telescreening. At this time, it is unclear whether nonspecialist photographers would evaluate undilated photographs at the point of care and, if needed, repeat photography with dilation.

Overall, the published medical literature is adequate to conclude that digital imaging systems are safe and effective alternatives to the gold standard of dilated indirect ophthalmoscopy coupled with biomicroscopy or stereoscopic fundus photography. Additional advantages of digital imaging systems include short examination time and the ability of nonophthalmologists to screen for DR.

Telescreening: Are the Patients Satisfied?

Patient satisfaction is important in implementing any screening strategy since feedback from patients can help to refine the model. For generations, doctors have used the traditional face-to-face clinical exam. Telescreening methods unfortunately lack this important aspect of health care system. Many researchers have argued about the satisfaction levels of the patient with telehealth programs.

However, Raman et al in 2006 ¹⁶ reported that almost 99% of their patients were satisfied with their screening via teleophthalmology in India. A similar study in 2008 done by Kumar et al showed good levels of satisfaction (94%) with teleophthalmology screening. ¹⁷

Tuulonen et al ¹⁸ from Japan reported that almost 60% of patients preferred the use of teleophthalmology as a choice for screening when asked. Other studies from around the world have also shown similar preferences for the use of teleophthalmology as screening tool for future ophthalmic screenings. Paul et al ¹⁹ in India found that 38% of patients found teleophthalmology more satisfying, whereas 60% felt that both models were equally satisfying.

In their study in Africa, Khaliq et al ²⁰ found that patient preference for teleophthalmology was driven primarily by convenience (73%) and decreased consultation time (58%). Other similar studies evaluating patient satisfaction with teleophthalmology have also reported similar reasons like reduction in cost, travel time, time off work, and increased assess to clinical support as the prime factors for choosing teleophthalmology.^17,18,21

Telescreening: Is It Cost-Effective?

Economic restraints and limitations, particularly in developing nations, necessitate a detailed cost-effective analysis of any diabetic screening program. Such an analysis can highlight the range of benefits as well as programs effectiveness.

Reports from the United States have shown that DR screening is not only cost-effective but also actually cost saving. ²² Bjorvig et al, ²³ in their economic analysis, concluded that telemedicine was a less expensive option for screening in places with higher patient workloads.

Gomez-Ulla et al ²⁴ did a cost analysis of DR screening by teleophthalmology versus standard ophthalmoscopy. The authors concluded that from the public health care system perspective, ophthalmoscopy is less costly than telescreening owing to the higher capital investment for teleophthalmology setup. From a global perspective, however, they reported that teleophthalmology is more efficient and convenient because the travel and time cost and loss of income for patients are lower.

We also reported that by using the World Health Organization threshold of cost-effectiveness, our rural teleophthalmology program was cost-effective ($1320 per QALY (Quality adjusted life years) compared to no screening from a health provider perspective. Screening intervals of up to a frequency of screening every 2 years also were cost-effective, but annual screening was not (>$3183 per QALY). From a societal perspective, telescreening up to a frequency of once every 5 years was cost-effective, but not more frequently. ²⁵ Another study utilizing telemedicine in South India describes a comprehensive project that provided diabetes prevention and health care at all levels (primordial, primary, secondary, and tertiary) in a rural areas. ²⁶

It can hence be concluded that telescreening not only is cost-effective but also provides the benefits of increased screening rates and opportunities for education of patients and local health care workers.

Guidelines for DR Screening Program

The American Telemedicine Association (ATA) and Ocular Telehealth Special Interest Group have established the guidelines for DR telescreening in 2004. ²⁷ They recommend that equipments used in telehealth system must conform to the requirements of the local and federal agencies. The diagnostic accuracy of the imaging system being used must be validated and the technology used should adhere to standards of Digital Imaging and Communication in Medicines (DICOM). Table 1 shows the differences between an ophthalmologist-based (screening in the presence of an ophthalmologist) and ophthalmologist-led (telescreening) models for DR screening.

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Table 1.

Difference Between Ophthalmology-led Versus Ophthalmologist-based Screening Models for Diabetic Retinopathy Screening.

	Ophthalmologist-based screening model	Ophthalmologist-led telescreening model
Feasibility	Needs trained expert	Less need for trained expert
Dilatation	Needed	May not be required
Maintenance	No	Required
Capital expenditure	Less	More
Revenue expenditure	More	Less

The ATA recognizes 4 categories of telescreening programs:

Working Model of DR Telescreening Program

The “Telehealth Practice Recommendations for Diabetic Retinopathy” divide DR telehealth program into 4 elements of care:

Each of these components requires personnel with specific duties and qualification, equipment and data transfer, legal requirements, validation, and quality control.

The data collected include patient examination findings (identification, demographic, and medical information) along with fundus image. These images are taken by a trained technician using a fundus camera. Images of both eyes of the patient are acquired under a fixed and predetermined protocol. Mydriasis using tropicamide may be required in some patients to obtain an image of sufficient quality.^15,27 Stereoscopy may be used to detect retinal thickening.^3,28,29 The data are then encrypted, to protect patients confidentiality, and transmitted to the main server via the Internet or satellite. At the reading center, an ophthalmologist or a specially trained staff member ³⁰ performs image grading and interpretation and then decides about the treatment plan and need for referral to a higher center. A report comprising findings and any medical advice by the specialist is made available to the patient at the peripheral imaging site itself.

Nonmydriatic fundus camera has a higher rate of unreadable photographs because of associated higher incidence of cataract amongst diabetic patients. This has led to the concept of “targeted mydriasis,” offering mydriasis only to selected groups of individuals for whom there is a suspicion of poor quality image acquisition. ¹⁵ Programs using pupil dilations should have a defined protocol to recognize and address the potential complications of angle closure glaucoma.

Conclusions

Telescreening for DR seems to be a cost-effective, accurate, and reliable method for screening for DR. Figure 1 shows the use of telemedicine in DR screening using a nonmydriatic camera. The coverage for screening is greatly enhanced. ATA has set up guidelines for telescreening that should be followed to provide quality screening services to people with diabetes. Early and accurate detection of DR requires a multipronged approach including screening, creating awareness, and training. The method and tools for screening are dependent on the available resources. In a vast country like India, with limited trained manpower for screening retinopathy and where health care facilities are concentrated in cities, teleophthalmology seems to be a good method for screening. The developments in telecommunications over the past decade have opened many new avenues for using telescreening for retinopathy. The trends in increasing mobile broadband use, increasing use of social media, and increasing e-commerce boost the potential of using information technology for DR care.

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Figure 1.

Telescreening van, satellite connectivity, and use of nonmydriatic camera.