Detection of retinal lesions in diabetic retinopathy: comparative evaluation of 7-field digital color photography versus red-free photography

Pradeep Venkatesh, Reetika Sharma, Nagender Vashist, Rajpal Vohra, Satpal Garg
International Ophthalmology 2015, 35 (5): 635-40
Red-free light allows better detection of vascular lesions as this wavelength is absorbed by hemoglobin; however, the current gold standard for the detection and grading of diabetic retinopathy remains 7-field color fundus photography. The goal of this study was to compare the ability of 7-field fundus photography using red-free light to detect retinopathy lesions with corresponding images captured using standard 7-field color photography. Non-stereoscopic standard 7-field 30° digital color fundus photography and 7-field 30° digital red-free fundus photography were performed in 200 eyes of 103 patients with various grades of diabetic retinopathy ranging from mild to moderate non-proliferative diabetic retinopathy to proliferative diabetic retinopathy. The color images (n = 1,400) were studied with corresponding red-free images (n = 1,400) by one retina consultant (PV) and two senior residents training in retina. The various retinal lesions [microaneurysms, hemorrhages, hard exudates, soft exudates, intra-retinal microvascular anomalies (IRMA), neovascularization of the retina elsewhere (NVE), and neovascularization of the disc (NVD)] detected by all three observers in each of the photographs were noted followed by determination of agreement scores using κ values (range 0-1). Kappa coefficient was categorized as poor (≤0), slight (0.01-0.20), fair (0.2 -0.40), moderate (0.41-0.60), substantial (0.61-0.80), and almost perfect (0.81-1). The number of lesions detected by red-free images alone was higher for all observers and all abnormalities except hard exudates. Detection of IRMA was especially higher for all observers with red-free images. Between image pairs, there was substantial agreement for detection of hard exudates (average κ = 0.62, range 0.60-0.65) and moderate agreement for detection of hemorrhages (average κ = 0.52, range 0.45-0.58), soft exudates (average κ = 0.51, range 0.42-0.61), NVE (average κ = 0.47, range 0.39-0.53), and NVD (average κ = 0.51, range 0.45-0.54). Fair agreement was noted for detection of microaneurysms (average κ = 0.29, range 0.20-0.39) and IRMA (average κ = 0.23, range 0.23-0.24). Inter-observer agreement with color images was substantial for hemorrhages (average κ = 0.72), soft exudates (average κ = 0.65), and NVD (average κ = 0.65); moderate for microaneurysms (average κ = 0.42), NVE (average κ = 0.44), and hard exudates (average κ = 0.59) and fair for IRMA (average κ = 0.21). Inter-observer agreement with red-free images was substantial for hard exudates (average κ = 0.63) and moderate for detection of hemorrhages (average κ = 0.56), SE (average κ = 0.60), IRMA (average κ = 0.50), NVE (average κ = 0.44), and NVD (average κ = 0.45). Digital red-free photography has a higher level of detection ability for all retinal lesions of diabetic retinopathy. More advanced grades of retinopathy are likely to be detected earlier with red-free imaging because of its better ability to detect IRMA, NVE, and NVD. Red-free monochromatic imaging of the retina is a more effective and less costly alternative for detection of vision-threatening diabetic retinopathy.


You are not logged in. Sign Up or Log In to join the discussion.

Related Papers

Available on the App Store

Available on the Play Store
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"