Abstract
Purpose: :
The 4 Wide Angle Fields (4W) Digital fundus imaging protocol captures approximately the same retinal area as the ETDRS 7 modified fields (7M) protocol, but with fewer images. We sought to evaluate the grading procedure and reproducibility using this technique.
Methods: :
48 eyes from the DRCRnet protocols were photographed using the 4W protocol using a camera with a 50 or 60 degree field of view. The fields consist of Field 2W centered temporal to the fovea, Field 1W located nasal to the disc, Field 4W and 5W are the superior and inferior temporal fields. Two senior ocular disease evaluators (ODE’s) independently evaluated the 4W stereo (4W-S) images using a modification of ETDRS Retinopathy Severity Scale, where the fundus was divided into quadrants and a more severe grade was assigned if all 4 quadrants were involved. The better side of the photographic pair was selected and images were evaluated again using the same procedure except using non-stereo (monoscopic) images (4W-M).
Results: :
Intergrader reproducibility for DR severity was 0.87 (95% CI0.8, 0.93) and 0.73 (95% CI 0.58, 0.89) for 4W-S and 4W-M respectively. Comparison between 4W-S and 4W-M showed exact agreement on 75% of eyes (weighted K= 0.84, 95% CI 0.76, 0.91).Evaluation of macular edema in 4W-S as compared to 7M was poor. Agreement on presence of any edema was 0.31 (95% CI 0.14, 0.48)* and CSME was 0.49 (95% CI 0.27, 0.71). Intergrader reproducibility for edema in 4W-S was 0.64 (95% CI 0.42, 0.87)* for presence of any edema and 0.62 (95% CI 0.39, 0.85) for CSME.
Conclusions: :
The poor intergrader reproducibility for 4W-M compared to 4W-S for retinopathy could be due to the inability to differentiate lesions without stereopsis. Evaluation of diabetic macular edema was not satisfactory with 4W. A possible explanation could be the wide angle which causes poor depth effect.4W images may be a reasonable option in some settings for the evaluation of diabetic retinopathy from color photographs, and macular edema can be assessed by OCT integrated evaluation. Added benefits are fewer photographic flashes for the patient and smaller image file sizes.*Simple Kappa used for RT Presence, Weighted Kappa used for all other results.
Keywords: diabetic retinopathy • clinical research methodology