Epidemiologic Assessment of Diabetic Retinopathy in Egypt Using Ultrawide Field Fundus Photographs

Overview

In 2013, it was estimated that 16% (7.5 million) of all Egyptian adults between the ages of 20 and 79 years have type 2 diabetes and 2.6 million have diabetic retinopathy. A small pilot study looking at 323 patients with previously diagnosed diabetes mellitus (DM) and 183 patients with newly diagnosed DM found that the prevalence of diabetic retinopathy (DR) was 48.3% and 10.4% in each group respectively. By 2035, the Middle Eastern Region and Egypt is projected to have an over 96% increase in the diabetes population. Ultrawide field (UWF) imaging is a novel technology that allows the visualization of approximately 82% of the retina in a single image. Its use in diabetic retinopathy (DR) has been widely explored both as a diagnostic as well as a screening tool. Using this technology, more of the peripheral retina can be readily visualized allowing significantly greater hemorrhages/microaneurysms, intraretinal microvascular abnormalities and non-perfusion to be detected. UWF imaging in patients with DM allowed the identification of a distinct sub-set of eyes with lesions that are predominantly distributed in the peripheral retina. Eyes with significantly greater DR lesions in the extended peripheral fields compared to their respective ETDRS fields are said to have predominantly peripheral lesions or PPL. Eyes with PPL are at greater risk of progressing to more advanced DR and developing proliferative diabetic retinopathy (PDR) after 4 years of follow up. The increased risk of vision threatening complications in eyes with PPL has made the identification of these eyes an essential part of DR evaluation and screening. Furthermore, the presence of lesions in the peripheral retina results in a more severe DR grade in approximately 20% of eyes thereby making this tool more accurate at grading DR severity. A recent DRCR retina network multicenter study established earlier findings confirming the validity of this tool in DR management. I-care Ophthalmology Center will acquire the first UWF device in Egypt, the Optos California (Optos Plc, Dunfermline). Scanning laser ophthalmoscopy UWF imaging has been approved by both the FDA and EMA since 2011. Patients with DM, with or without known DR, will be imaged using the UWF imaging device both for diagnosis and screening purposes at I-care Ophthalmology center after informed consent. These images will be graded for the level of retinopathy and the presence/absence of PPL by certified trained graders. Internal validation and continuous quality control will routinely be conducted. Patients with vision threatening retinopathy (moderate non-proliferative diabetic retinopathy or worse, or the presence of diabetic macular edema) will be instructed to come back for further retinal evaluation and ancillary testing. Patients with mild retinopathy will be instructed to come for yearly follow up imaging. The expected duration for data collection will be 5-years, with interim data analysis on a yearly basis. The design although cross sectional, will have a prospective sub-analysis group in patients who have repeat imaging. Data collection and imaging will be conducted in Egypt and anonymized deidentified data will be shared with the Joslin Diabetes Center, Harvard Ophthalmology Department for joint research purposes. Data will be analyzed for the prevalence of DR and the distribution of DR severity levels in the studied population. In addition, the presence and absence of PPL and its association with DR progression will be studied. Non-modifiable (duration of DM, age of onset, type of DM etc.) and modifiable risk factors (HbA1c, hypertension, hyperlipidemia etc.) for increased risk of DR progression will also be analyzed. Sensitivity analysis will explore the sensitivity/specificity of initial DR grading compared to trained retina specialists.