13.1Introduction

Worldwide, the prevalence of diabetes mellitus, particularly type II diabetes, is rising at an alarming rate. The global prevalence of diabetes is estimated to increase, from 4% in 1995 to 5.4% by 2025 [1]. The World Health Organization (WHO) has predicted that the major burden will occur in the developing countries. The countries with the largest number of diabetic people are, and will be in the year 2025, India, China, and United States [1]. If we look at the absolute numbers, WHO and International Diabetes Federation (IDF) have estimated that the worldwide number of adult-onset diabetes cases will double – from the current 171 million to 366 million cases – by 2030 [2]. In developed countries, the rate of increase is projected at approximately 42%, and in developing countries, particularly in India, it is projected at 150% [2].

T. Sharma • R. Raman

Shri Bhagwan Mahavir Vitreoretinal Services, Sankara Nethralaya Eye Institute,

18 College Road, Chennai 600 006, India

S. John ( )

Department of Teleophthalmology, Sankara Nethralaya Eye Institute, 18 College Road, Chennai 600 006, India e-mail: drsj@snmail.org

S.S. Badrinath

Sankara Nethralaya Eye Institute,

18 College Road, Chennai 600 006, India

13.2Burden of Diabetes and Diabetic Retinopathy in India

In 2007, India led the global top ten countries in terms of the highest diabetic population (40.9 million), followed by China (39.8 million). Developing countries account for seven of the world’s top ten countries with maximum diabetic population. However, in 2025, also the top three positions are expected to remain unchanged with India (69.9 million), China (59.3 million), and USA (25.4 million) of diabetic population [3]. With the diabetic population expected to increase in the coming decades, India will have to incur huge expenditure on health in the future. Twenty years ago, diabetic retinopathy was the 17th leading cause of blindness in India. Today, diabetesrelated blindness ranks sixth among the leading causes of blindness in India.

The prevalence of diabetes among the urban Indian population is reported to be 28.2%, and the prevalence of diabetic retinopathy in the general population is 3.5%. The prevalence of diabetic retinopathy in the population with diabetes mellitus is said to be 18.0% [4]. According to the same report, every fourth individual, more than 40 years in urban India, is a diabetic, and every sixth diabetic has diabetic retinopathy.

In rural India, the prevalence of diabetic retinopathy is 17.6%. The prevalence of diabetic retinopathy in known diabetics is 17.8% and in persons with newly detected diabetes is 10.2%. The prevalence of referable (sight-threatening) diabetic retinopathy is 5.3% [5]. Unlike the prevalence of

Table 13.1 Difference between store and forward and real time in DR screening

diabetes, the prevalence of diabetic retinopathy does not show a rural–urban difference.

13.3Diabetic Retinopathy Screening Models

The models for screening diabetic retinopathy are divided into ophthalmologist-based model and ophthalmologist-led model. In the former, the ophthalmologist is physically present at the screening venue, and he screens the population himself by performing dilated retinal evaluation by indirect ophthalmoscope/direct ophthalmoscope/slit-lamp biomicroscopy. Whereas in the ophthalmologistled model, the paramedical staff visits the screening venue and acquires data/images. These images are then transferred by satellite to the base hospital where the ophthalmologist interprets the images. The salient features of the two models are summarized in Table 13.1. Mobile telescreening is an ophthalmologist-led screening program that takes eye care facilities to the rural population.

13.4Need for Telescreening

In India, 80% of population resides in rural area, whereas 70% of health-care resources are in urban areas. It has been estimated that the ophthalmologist to patient ratio is at a dismal 1:100,000 for the Indian population and that 70% of the ophthalmologists practice in urban areas. At the same time, currently, few ophthalmologists in India have been trained in the diagnosis and treatment of diabetic retinopathy. The limited number of ophthalmologists available in the country adversely affects conducting an

Table 13.2 Difference between ophthalmologist-led and ophthalmologist-based models

ophthalmologist-based screening service in India. As a result, the optimal screening model in India may be an “ophthalmologist-led” system. The technology to facilitate this type of service is telemedicine. Telemedicine includes the assessment and analysis of patient information and interaction by a health professional who is separated temporally and/or spatially from the patient [6]. Table 13.2 shows the difference between these models.

A mobile telescreening technology with a satellite connection between the mobile van and the medical center enables ophthalmologists working in the base hospital to screen the rural population. This minimizes the number of unnecessary referrals to the main center for diagnostic investigation and treatment and also reduces the cost of the screening program.

13.5Guidelines for Telescreening

In 2003, the American Telemedicine Association (ATA) charged the ATA Ocular Telehealth Special Interest Group (SIG) to compose and disseminate Telehealth Practice Recommendations for Diabetic Retinopathy [7].

The goals for a telescreening program include:

1.Improved access to the diagnosis and management of DR

2.Reduction in the incidence of vision loss due to DR

3.Decreased cost of identifying patients with diabetic retinopathy

4.Promoting telehealth to enhance the efficiency and clinical effectiveness of evaluation, diagnosis, and management of DR

5.Promoting telehealth to enhance the availability, quality, efficiency, and cost-effectiveness of remote evaluation for DR

risk screening. Opportunistic screening and highrisk screening complement each other.

13.6ATA Categories of DR Telescreening Validation

1.Category I validated systems:

Identify patients who have no or minimal nonproliferative diabetic retinopathy and those who have more severe diseases.

Refer all patients with greater than minimal DR for further evaluation by an ophthalmologist.

2.Category 2 validation systems:

Identify patients who do not appear to have sightthreatening diseases (including DME, severe NPDR, or PDR) and those who have potentially sight-threatening diabetic retinopathy.

Patients referred with this type of system generally require prompt treatment such as laser photocoagulation.

3.Category 3 validation systems:

Allow patient management to match clinical recommendations based on clinical retinal examination through dilated pupils.

4.Category 4 validation systems:

Indicate a program which can replace ETDRS photos in any clinical or research program. Categories 3 and 4 are more extensive and are generally not necessary for screening programs which differentiates accurate ETDRS levels of DR.

13.7Yield of Diabetic Retinopathy in a Telescreening Model

The yield of diabetic retinopathy in a telescreening model depends, largely, upon whether it is an opportunistic screening or a high-risk screening. An opportunistic screening is the ideal screening method, with wide coverage, in which screening of diabetic retinopathy is done as a part of comprehensive eye examination, whereas high-risk screening is targeted screening performed in diabetic retinopathy screening camps. Hence, the yield of diabetic retinopathy is higher in high-

13.8How Are Images Transferred

The data/images can be transferred via the “store and forward” method or as “real-time” images through videoconferencing. In the “store and forward” method, the images are captured, stored, and forwarded for retrieval by remote ophthalmologist at a later time, whereas in real-time imaging, the data/images are captured and simultaneously seen by the remote ophthalmologist. The success of the real-time teleconsultation depends on the quality of connectivity between the central hubs or main center where the ophthalmologist examines the digital data and the remote location where the patient is examined [8]. The salient features of the two methods are described in Table 13.1.

13.9Checklist for Telescreening Set-up

The following checklist is very useful while establishing a telescreening set-up:

•Visual acuity chart

•Slit lamp

•Tonopen

•Nonmydriatic fundus camera

•Videoconferencing unit

•Telemedicine software

•Scanner and printer

•Laptop

•LCD monitor

13.10How Many Fields Are Enough for Diabetic Retinopathy Screening

•Inoveon Diabetic Retinopathy (DR-3DT) system (Inoveon Corporation, Oklahoma City, OK): 7 fields [9]

•Joslin Vision Network (Beetham Eye Institute, Joslin Diabetes Center, Boston, MA): 3 fields [10]