Introduction

The criteria for human diseases amenable to screening approaches were defined by the World Health Organization in 1968¹ and diabetic retinopathy fulfills all of these. Visual impairment due to diabetic retinopathy is a significant health problem; however, it has a recognizable presymptomatic stage.² The DCCT and the UKPDS established that intensive diabetes management to obtain near-euglycemic control can prevent and delay the progression of diabetic retinopathy in patients with diabetes.^3,4 Timely laser photocoagulation therapy can also prevent loss of vision in a large proportion of patients with sight-threatening diabetic retinopathy.⁵ Screening for diabetic retinopathy saves vision at a relatively low cost, which has been demonstrated in various studies.^6,7 The American Academy of Ophthalmology recommends annual dilated eye examinations beginning at the time of diagnosis for patients with type II diabetes.² For those with type I diabetes, the recommendation is retinal examination 3–5 years after diagnosis, with annual exams thereafter.² The barriers for successful screening are numerous and include the high cost of care, poor awareness levels, lack of symptoms in the early stages of disease, socioeconomic factors and poor geographical access to care.⁸ Current screening programs for diabetic retinopathy are either ophthalmologist-based (with actual presence of the ophthalmologist at the site of screening) or ophthalmologist-led (no ophthalmologist at the site of screening). Table 50.1 summarizes the key differences between the two models. Telemedicine for retinopathy screening is an ophthalmologist-led screening model, which may be a logical potential alternative for patients who have been noncompliant with the traditional face-to-face examination by an ophthalmologist. Telemedicine is the exchange of medical data by electronic telecommunications technology allowing a patient’s medical problems to be evaluated, monitored, and possibly treated while the patient and physician are located at sites physically remote from each other.⁹ Ophthalmology is uniquely suited for telemedicine as it is a highly visual and image intensive specialty and digital imagery is easily transmitted by electronic means. Remote assessment for diabetic retinopathy provides an ideal model for telehealth screening initiatives and, in fact, has become one of the most common uses for telemedicine in ophthalmology.

Table 50.1 Differences between the ophthalmologist-led and ophthalmologist-based models for screening for diabetic retinopathy

Guidelines for telescreening program

Steps of telescreening

The flow of steps of the telescreening process is diagrammed in Fig. 50.1. In brief, patient enrollment is performed after defining the data to be collected. Since ocular telescreening services for diabetic retinopathy satisfy the criteria of low risk telehealth procedures and are within commonly accepted standards of practice, signature consent may not be required. However, practitioners should provide patients with information about the telescreening program they would reasonably want to know, including differences between care delivered using ocular telehealth approaches versus traditional face-to-face encounters, and a description of what is to be done at the patient’s site and the remote site. The data collected includes fundus images, along with patient examination findings (identification, demographic, and medical information) and some morphological information that is used to make a clinical decision. Fundus images of both eyes of the patient are acquired under a fixed, predetermined imaging protocol. These images are taken by a trained technician using a fundus camera. Due to various factors, the quality of the acquired images may be below the grading standard, thus not providing any meaningful information for examination by the reader. This can be addressed by employing an automatic image quality assessment module. An automatic image quality assessment module will ensure that the images transmitted for diagnosis conform to prescribed gradability standards. During the quality assurance process, the gradable images are selected for compression, whereas the identification of poor quality images can trigger reimaging by the technician. The patient data comprising the clinical data and the fundus images are compressed to make them suitable for low-bandwidth network connectivity. The patient data are transmitted to the servers via the Internet or satellite. At the reading center, the images are graded for presence of retinal lesions and the determination of a diabetic retinopathy level; referred to “next level” graders if necessary; and a retinopathy structured report is generated. Only qualified readers should perform retinal image grading and interpretation. If a reader is not a licensed eye care provider, specific training is required. A licensed, qualified eye care provider with expertise in diabetic retinopathy and familiarity with telescreening program technology should supervise the readers. An adjudicating reader (an ophthalmologist with special qualifications in diabetic retinopathy by training or experience) may resolve discrepant interpretations. Image processing algorithms should undergo rigorous clinical validation. A report comprising the findings, the results and the medical advice given by the expert is made available to the patient and the care team at the remote site through an accessible interface.

Fig. 50.1 Flowchart representing the steps of telescreening. This figure shows the sequential steps of telescreening carried out at the imaging center and the reading center.

Technical considerations