Telemedicine in Diabetic Retinopathy: Current Status and Future Directions

Abstract

Telemedicine is exchange of medical data by electronic telecommunications technology that allows a patient's medical problems evaluated and monitored by a remotely located physician. Over the years, telemedicine and telescreening have become important components in health care, in both disease detection and treatment. Highly visual and image intensive ophthalmology is uniquely suited for telemedicine. Because of rising disease burden coupled with high opportunity cost in detection, diabetic retinopathy is an ideal ophthalmic disease for telescreening and decision-making. It fits to Wilson and Jungner's all 10 criteria of screening for chronic diseases and the American Telehealth Association's 4 screening categories.

INTRODUCTION

Diabetes mellitus (DM) is a global epidemic.¹ An estimated 3.4 million people died in 2004 from consequences of high fasting blood sugar.² More than 80% of diabetes deaths occur in low- and middle-income countries.³ The World Health Organization (WHO) projects that diabetes will be the 7^th leading cause of death in 2030.⁴ It is estimated that 439 million people are likely to have DM by year 2030 in the world and that this increase is disproportionately more in developing countries (69% in developing countries vs. 20% in developed countries with 2010 as baseline).⁵ This will result in a heavy burden on the health care system because of several DM related complications.

Diabetic retinopathy (DR), the leading cause of visual disability in diabetics, is an important complication of DM. The reported prevalence of DR in India ranges from 17.6% to 28.2%.⁶,⁷,⁸,⁹ With this prevalence, the number of people with DM is expected to increase to 79.4 million and patients with DR would increase to 22.4 million in another two decades.⁵ The potential economic and social burden of DM and DR demands for a definite need for an effective screening strategy, accurate case detection and treatment effective for both DM and DR. Globally, there is an increase in vision-threatening retinopathy.¹⁰

Over the past decade, there have been rapid strides in progress in the fields of telecommunication and medical imaging. These have opened newer avenues to creating efficient screening strategy for DR. Newer techniques like stereoscopic imaging, nonmydriatic camera and mobile phone based fundus camera show comparable sensitivity and specificity in diagnosing DR.¹¹,¹² India ranks third in the world in number of Internet users by volume. Additionally, 70% has access to mobile phones, and 39% of them live in rural areas. Teledensity has increased from merely 12.1% to 73.3%, a growth of 600%, during the past 5 years.¹³ This makes screening of DR using imaging and teleophthalmology a distinct possibility that can revolutionize the health care system.

DOES DIABETIC RETINOPATHY FIT INTO SCREENING CRITERIA?

Diabetic retinopathy is a perfect situation for screening. Wilson and Jungner had defined 10 criteria for screening of chronic disease in 1968.¹⁴ DR screening fits into this criterion [Table 1].

Table 1.

Wilson and Jungner screening criteria and DR screening alignment

DIABETIC RETINOPATHY SCREENING CRITERIA

One of the main motivations for screening for DR is the established efficacy of laser photocoagulation in preventing visual loss. Two large randomized clinical trials, the DR study, and the early treatment DR study, have provided the strongest support for therapeutic benefit of photocoagulation.¹⁵,¹⁶ This is further augmented from the current evidence of benefit from anti VEGF therapy in a few of randomized trials.¹⁷,¹⁸,¹⁹ Since some patients with vision-threatening pathologies may not have symptoms, ongoing evaluation for retinopathy is a valuable and required strategy.

The American Diabetes Association recommends retinopathy screening with yearly retinal examination beginning at the time of diagnosis of diabetes for all patients age 30 years and older.²⁰ Annual examinations are recommended for patients under age 30 years beginning within 3–5 years after diagnosis of diabetes. The classical tools used in DR screening include direct ophthalmoscopy, indirect ophthalmoscopy, slit lamp biomicroscopy and fundus photography. These are either optometrist led (direct ophthalmoscopy, fundus photography) or ophthalmologist led (direct and indirect ophthalmoscopy, slit lamp biomicroscopy and fundus photography).

WHAT IS TELEMEDICINE IN DIABETIC RETINOPATHY CARE?

Telemedicine is exchange of medical data by electronic telecommunications technology that allows a patient's medical problems evaluated and monitored by a remotely located physician.²¹ Application of telemedicine for screening of a disease is called telescreening. Ophthalmology being highly visual and image intensive, is uniquely suited for telemedicine and telescreening.

Normally, diabetics do not visit an ophthalmologist unless they have visual defects. The fundus images can be captured at the physician's or diabetologists facility at the time of a regular diabetic check-up. This kind of opportunistic screening helps in improved screening of these patients. The fundus pictures obtained in a nonmydriatic digital retinal camera are then transmitted through internet, to a reading and grading center where a retinal expert or a trained grader reads them remotely.¹² The images are read, a report regarding the status of the retinopathy is generated and the follow-up suggestions are made by the ophthalmologist at a remote location; this report is returned by internet to the patient's location from where the images were taken originally. In areas of scarce medical care, a mobile van with communication capabilities and fundus camera helps. The diabetic patients are pooled in one area, and their fundus pictures are captured and sent to a centralized reading center. The other sequences are similar.

In addition to technical similarity, teleophthalmology in DR care is both efficient and cost-effective. The efficacy of digital photography vis-à-vis the traditional film-based photography and single-field fundus photo vis-à-vis the traditional seven-field fundus photo are recently reported by the American Academy of Ophthalmology.²² We have reported that nonmydriatic fundus photography compared to indirect ophthalmoscopy was 62.5% (95% confidence interval [CI]: 24–91) sensitive and 98.7% (95% CI: 93–99) sensitive;²³ we have also reported that telescreening is as good as ophthalmologist led screening for detection of DR.²⁴ Rudnisky et al. have reported good agreement between high-resolution stereoscopic digital fundus photography and contact lens biomicroscopy²⁵ At the same time, despite lack of face-to-face contact, patient satisfaction has remained unchanged in telescreening.²⁶,²⁷,²⁸,²⁹,³⁰,³¹ It is also less expensive in places with higher patient workload³² and is convenient as it saves the opportunity costs connected with DR screening such as time, travel, and loss of income.³³ Rachapelle et al.³⁴ also reported that using the WHO threshold of cost-effectiveness, rural teleophthalmology is cost-effective compared to no screening as long it is done at interval longer than 1-year.

GUIDELINES FOR DIABETIC RETINOPATHY SCREENING PROGRAM

The American Telemedicine Association (ATA) and Ocular Telehealth Special Interest Group have established the guidelines for DR telescreening in 2004.³⁵ They recommend that equipment used in telehealth system must conform to the local requirements and that the technology should adhere to standards of Digital Imaging and Communication in Medicines (DICOM).

The ATA recognizes four categories of telescreening programs [Table 2]:

Table 2.

ATA telescreening categories

While fundus photo taken in nonmydriatic fundus camera is often used in telescreening, mydraisis usually reduces the proportion of ungradable photographs.³⁶ One could consider mydrasis based on the visual acuity (<20/40) and age (>59 years)³⁷ or in case of unsatisfactory nonmydiatric fundus camera photograph.³⁸

CURRENT STATUS

The setting

Currently, the use of telescreening for DR is used in two settings: (a) Screening by nonphysician/nonophthalmologist. This is usually by an optician/optometrist using a fundus camera, and the diagnosis is given from a remote location; (b) Screening retinopathy by physician/nonophthalmologist. This seems to be an ideal situation as physicians are the first contact for a person with DM.

The screening tools

These include a wide variety of fundus cameras-traditional fundus camera, miniature tabletop fundus camera integrated adaptor-detector based handheld ophthalmic cameras, and smartphone based ophthalmic cameras. Of these, the smartphone based cameras are more cost-effective though; but they need mydriasis.

The image transmission

Majority of telemedicine models today use the internet to transmit images.³³,³⁹ Satellite transmission is a more preferred option in rural areas and mobile clinics because of less optimal infrastructure. The images and reports are transmitted digitally via electronic picture archiving and communication systems (PACS). A PACS consists of four components: The imaging instrumentation, a secured network for transmission of patient information, workstations for interpreting and reviewing images, and archives for the storage and retrieval of images and reports. The universal format for PACS image storage and transfer is DICOM. To minimize errors, data communications should be compliant with DICOM standards.

The reporting

This includes grading of image quality, presence or absence of retinopathy, referable/nonreferable retinopathy and the grading severity of the disease.

The current status of telescreening in DR is shown in Figure 1.

Figure 1.

Current status of telescreening in diabetic retinopathy

FUTURE DIRECTIONS

Recent advances in better and faster telecommunication technology including “cloud” storage, miniaturization of diagnostic equipment including digital cameras, and automation of retinal image analysis, offer excellent opportunities to expand telescreening services to more remote areas. In coming years, there would be a shift from telephone landlines to wireless, and from manual to automatic detection of retinal lesions that will enhance the teleophthalmology capabilities both in value and volume. In all probability, automatic detection of retinal lesion images will play a major role in screening and management of DR in future.⁴⁰

Over the years, telemedicine and screening have become important components in health care, in both disease detection and treatment. The first step in telemedicine in management of DR is screening for patients with retinopathy. The emerging screening criteria proposed over the past 40 plus years ago by Wilson and Jungner should respond to a recognized need.⁴¹ They include the following: The objectives of screening should be defined at the outset; there should be a defined target population; there should be scientific evidence of screening program effectiveness; the program should integrate education, clinical services, and management; there should be quality assurance, with mechanisms to minimize potential risks of screening; the program should ensure informed choice, confidentiality and respect for autonomy; the program should promote equity and access to screening for the entire target population; program evaluation should be planned from the outset; finally the overall benefits of screening should outweigh the harm.