Diagnostic test accuracy of diabetic retinopathy screening by physician graders using a hand-held non-mydriatic retinal camera at a tertiary level medical clinic

Abstract

Background The evidence on diagnostic test accuracy (DTA) of diabetic retinopathy (DR) screening utilising photographic studies by non-ophthalmologist personnel in low and middle-income country (LMIC) settings is scarce. We aimed to assess DTA of DR screening using a nonmydriatic hand-held digital camera by trained general physicians in a non-ophthalmic setting. Methods This study is a validation of a screening intervention. We selected 700 people with diabetes (PwDM) > 18 years of age, not previously screened or treated for DR, presenting at a tertiary medical clinic in Sri Lanka. Two-field retinal imaging was used to capture fundus images before and after pupil dilatation, using a hand-held non-mydriatic (Visuscout 100®-Germany) digital retinal camera. The images were captured and graded by two trained, masked independent physician graders. The DTA of different levels of DR was assessed comparing physician’s grading with a retinologist’s clinical examination by mydriatic bio-microscopy, according to a locally adopted guideline. Results Seven hundred eligible PwDM were screened by physician graders. The mean age of participants was 60.8 years (SD ±10.08) and mean duration of DM was 9.9 years (SD ±8.09). Ungradable image proportion in non-mydriatic imaging was 43.4% (either eye-31.3%, both eyes 12.1%). This decreased to 12.8% (either eye-11.6%, both eyes-1.2%) following pupil dilatation. In comparison to detection of any level of DR, a referable level DR (moderate non-proliferative DR and levels above) showed a higher level of DTA. The sensitivity of the defined referable DR was 88.7% (95% CI 81.7–93.8%) for grader 1 (positive predictive value [PPV] 59.1%) and 92.5% (95% CI 86.4–96.5%) for grader 2 (PPV 68%), using mydriatic imaging, after including ungradable images as screen positives. The specificity was 94.9% (95% CI 93.6–96.0%) for grader 1 (negative predictive value [NPV] 99%) and 96.4% (95% CI 95.3–97.3%) for grader 2 (NPV 99.4%). Conclusions The Physicians grading of images from a digital hand-held non-mydriatic camera at a medical clinic, with dilatation of pupil of those who have ungradable images, provides a valid modality to identify referable level of DR. This could be a feasible alternative modality to the existing opportunistic screening to improve the access and coverage. Trial registration Current Controlled Trials ISRCTN47559703 . Date of Registration 18th March 2019, Retrospectively registered. Electronic supplementary material The online version of this article (10.1186/s12886-019-1092-3) contains supplementary material, which is available to authorized users.

<p>Agreement on Grading Retinal Findings of Patients with Diabetes Using Fundus Photographs by Allied Medical Personnel when Compared to an Ophthalmologist at a Diabetic Retinopathy Screening Program in Nepal</p>

“…For grader 2 (family physician) sensitivity was 92.5% and specificity was 96.4%. 30 This study findings showed slightly better results when compared to our study. This difference could be because of inclusion of only referable DR cases and mydriatic fundus photographs in their study.…”

A scalable physician-level deep learning algorithm detects universal trauma on pelvic radiographs

“…The distribution of the dataset largely affects the test performance of the computer-aided diagnosis algorithm 26 . Although some studies have demonstrated fair levels of accuracy with a balanced dataset, the low incidence of positive findings in the clinical scenario leads to a low PPV and a large number of false-positive cases 9 , 27 , 28 . Inverse probability was also used to estimate the algorithm behavior with the population distribution 9 .…”

Diagnostic Accuracy of Detecting Diabetic Retinopathy by Using Digital Fundus Photographs in the Peripheral Health Facilities of Bangladesh: Validation Study

“…Some studies in India, Sri Lanka, and Pakistan report satisfactory test accuracy for non-ophthalmologist screening [ 6 , 9 , 31 , 32 ]. Using digital fundus photographs and a nonmydriatic approach, “physician graders” in Sri Lanka showed a sensitivity of 88.7% and specificity of 94.9% [ 10 ]. In Pakistan, optometrists showed 72% sensitivity and 86.3% specificity [ 32 ].…”

“…In this study, a lower rate of ungradable images was reported (56/1511, 4.1%) than that reported in similar health facility–based studies in the South Asian context. A technical failure rate of 7.5% was noted in another study in Bangladesh [ 35 ], which rose to 12% in Sri Lanka [ 10 ]. The higher level of gradeability observed in our study is probably a function of the exclusion criteria or the image-taking technique that was employed.…”

“…A recent systematic review reported that poor knowledge and attitudes to asymptomatic eye screening are prevalent both among health care providers and patients [ 9 ]. At the health care system level, the lack of equipment, insufficiently skilled professionals, nonfunctioning referral mechanisms, and inadequate data within national management information systems are the main barriers [ 10 ]. Moreover, routine diabetic retinopathy screening is not always feasible for eye consultants, given their availability versus the load of patients with diabetes.…”