Researchers from the University of Brescia, Italy have published research findings suggesting that smartphones, in combination with an external lens device, can accurately detect retinal lesions for the grading of diabetic retinopathy (DR). In a publication in the American Journal of Ophthalmology the Italian research group argue that smartphone devices, coupled with the third party lens device, may be capable of being used as a DR screening tool in a variety of environments. Research, conducted by the team of trained ophthalmologists, showed that agreement between the two methods was observed in 204 of 240 eyes (85%). Compared to bio-microscopy, the sensitivity and specificity of smartphone ophthalmoscopy for the detection of clinically significant macular edema (CSME) were 81% and 98%, respectively. The authors of the study pointed out that smart-phone ophthalmoscopy and biomicroscopy could not be used to examine the fundus and grade DR in only 9 eyes (3.75%) and 4 eyes (1.7%), respectively, due to cataract and/or small pupil diameter.
The researchers recruited a total of 120 diabetic patients each of which underwent dilated retinal digital imaging with a smartphone ophthalmoscope. Subsequent to the smartphone imaging, each of the patients were then referred for a comprehensive dilated retinal bio-microscopy with a slit lamp performed by a retinal specialist. DR was graded according to the International Clinical Diabetic Retinopathy Disease Severity scale (ICDRDS) [no apparent retinopathy, mild non-proliferative DR (NPDR, micro-aneurysms only), moderate NPDR (more than just micro-aneurysms but less than severe NPDR), severe NPDR (more than 20 intraretinal hemorrhages in each of the 4 quadrants, definite venous beading in 2 or more quadrants, and prominent intraretinal micro-vascular abnormalities in 1 or more quadrants), or proliferative DR (neovascularizations and vitreous/pre-retinal hemorrhage)].
The researchers used the Apple iPhone 5, together with the third party device from a private company, “D-Eye”. The D-Eye adapter is an optical “fundus lens” device capable of being magnetically attached to the smartphone. The process uses the LED light source on the phone while the D-Eye lens facilitates the smartphone camera capturing high-definition video and still images of the retina. The examiner captures the images which can then be sent wirelessly to a database for post-processing and analysis. In respect of detecting the presence or absence of CSME, the authors of the study stated that the smartphone option had “sensitivity and specificity comparable to those of a high-end fundus camera”. In addition, the authors reported that the resolution achievable with the D-Eye device combined with an iPhone 5 (8-megapixel camera) is approximately 150 pixels per retinal degree, which is understood to exceed the image resolution benchmarks of 6 megapixels and 30 pixels per degree, outlined by the United Kingdom’s National Health Service. The authors conclude that, “the combination of affordability, portability, connectivity, and easy-to-use features of this ophthalmoscopy system provides a foundational platform, based on which a number of revolutionary screening programs can potentially be designed.”