Diabetic retinopathy: the unmet needs for screening and a review of potential solutions.

Diabetic retinopathy remains the leading cause of severe vision loss and blindness in the developed world, in spite of recognized ocular treatments that are successful at reducing the rate of vision impairment. Retinal photography appears a promising method to perform screening in such a setting utilizing new 45 degrees + retinal cameras that do not require pupil dilation and can be operated by a trained, nonophthalmic technician. Certain developments may make the photography more successful including the conversion to electronic chip camera sensors that allow each picture as it is taken to be immediately projected onto a monitor for evaluation and assessment. Utilizing a nonmydriatic camera, studies of single-field photography through a dilated pupil have demonstrated superior or equal sensitivity to fundus examination by an ophthalmologist in a number of studies. However, photography without pupil dilation, especially in the older age group may result in poor-quality photographs owing to intense bilateral pupil constriction after the first images and also due to the presence of cataracts. Computer analysis of the retinal images allows extraction of quantitative data, not only of the diabetic lesions but also of vascular changes that, up until now, have been impossible by human grading and potentially allows a much more detailed and quantitative evaluation of the progression of retinopathy over time. When success of image processing algorithms is demonstrated for a large number of images taken under screening conditions, the benefits of retinal photography and image processing to provide timely, reliable, quantitative and cost-effective results, will make this the preferred method over physician examination or human grader evaluation of the images.