Review of retinal cameras for global coverage of diabetic retinopathy screening

Abstract

The global burden of diabetes has resulted in an increase in the prevalence of diabetic retinopathy (DR), a microvascular complication of diabetes. Lifelong repetitive screening for DR is essential for early detection and timely management to prevent visual impairment due to the silent sight-threatening disorder. Colour fundus photography (CFP) is helpful for documentation of the retinopathy as well as for counselling the patient. CFP has established roles in DR screening, detection, progression and monitoring of treatment response. DR screening programmes use validated mydriatic or non-mydriatic fundus cameras for retinal imaging and trained image graders identify referable DR. Smartphone-based fundus cameras and handheld fundus cameras that are cost-effective, portable and easy to handle in remote places are gaining popularity in recent years. The images captured with these low-cost devices can be immediately sent to trained ophthalmologists for grading of DR. Recent increase in numbers of telemedicine programmes based on imaging with digital fundus cameras and remote interpretation has facilitated larger population coverage of DR screening and timely referral of those with sight-threatening DR to ophthalmologists. Good-quality retinal imaging and accurate diagnosis are essential to reduce inappropriate referrals. Advances in digital imaging such as ultra-wide field imaging and multi-modal imaging have opened new avenues for assessing DR. Fundus cameras with integrated artificial intelligence (AI)-based automated algorithms can also provide instant DR diagnosis and reduce the burden of healthcare systems. We review the different types of fundus cameras currently used in DR screening and management around the world.

Artificial Intelligence-Based Diagnosis of Diabetes Mellitus: Combining Fundus Photography with Traditional Chinese Medicine Diagnostic Methodology

“…There are numerous related studies; for instance, references [25][26][27] focused on the use of artificial intelligence in detecting diabetes; however, these studies mainly focused on software and used hospital data. Other studies [28][29][30] combined software and hardware, as did our study and were related to diabetes; however, they focused only on diabetic retinopathy, which is a complication of diabetes. Similar studies have attempted to use a convenient and noninvasive method to diagnose diabetes and have achieved an accuracy score higher than 0.85 [31,32].…”

Imaging Modalities Employed in Diabetic Retinopathy Screening: A Review and Meta-Analysis

“…This was presumably associated with colour distortion from the machine and, therefore, requires significant magnification of the images to evaluate discrete retinal lesions. The recently released Clarus 500 and Clarus 700 (Carl Zeiss Meditec AG, Jena, Germany) capture "true-color" images that may potentially enable more accurate identification of DR lesions, although this has yet to be demonstrated in clinical trials [130]. Within the currently published studies, images obtained with Clarus were consistent with current UWF-SLO devices in assessing the severity of DR, with no statistically significant difference in patient or technician preference, and image acquisition time [131][132][133].…”

Smartphone Ophthalmoscopy: is there a place for it?

“…The concept here is not necessarily a binocular visualization as we have seen it on indirect ophthalmoscopy, but it intends to acquire a wider field of view like that of an indirect ophthalmoscope. Using different lenses, an image spanning from standard photograph to wide-angled retinal pictures can be acquired, 17 and unlike the head-band assisted indirect ophthalmoscopes or the fixed imaging devices (fundus camera and other montage/wider imaging tools), just using the smartphones with an attachment the wide-angled retinal picture can be captured. The following points highlight the overall concept of wide angled retinal imaging using smartphones.…”

“…19,20 The available range of lenses here is immense, with each having different fields of capture and variable configuration. 17 Thus, cumulatively, smartphone fundus photography can be effectively used for screening purposes (including macular pathologies, diabetic retinopathy, retinopathy of pre-maturity, retinoblastoma and others). This specially aids in decentralising multi-speciality health care in developing countries.…”