A novel noninvasive detection method for retinal nonperfusion using confocal red-free imaging

Purpose: To report confocal red-free blue reflectance imaging as a novel, noninvasive imaging modality for the detection of retinal nonperfusion and to compare its effectiveness with that of fluorescein angiography (FA) in diabetic retinopathy (DR) and retinal vein occlusion (RVO).

Design: Evaluation of diagnostic technology, retrospective observational case series.

Participants: We enrolled 54 eyes of 44 patients with DR or RVO that had definite retinal nonperfusion on FA.

Methods: All patients underwent red-free blue reflectance imaging and FA using a confocal scanning laser ophthalmoscope. For all patients, macular and midperipheral retinal nonperfusion were identified on both confocal red-free and corresponding FA images, and were delineated by 2 independent readers. We evaluated the correspondence of the 2 imaging methods by comparing the sizes of the delineated areas and obtaining the overlapping ratio after image processing.

Main outcome measures: Comparison of size and overlapping correspondence between delineated area of retinal nonperfusion obtained by FA and confocal red-free imaging.

Results: Image analysis showed a high correlation (r>0.9) in the mean size of retinal nonperfusion between confocal red-free and corresponding FA images with DR or RVO. Reliable agreement between the 2 methods was confirmed by size comparisons (P = 0.563) and overlapping correspondence (overlapping ratio, 0.76) of the delineated area.

Conclusions: Our findings suggest that confocal red-free imaging is a simple, reliable, safe, and noninvasive method for effectively plotting retinal nonperfusion. This procedure, first reported herein, has the potential to be used for the noninvasive detection and quantification of retinal nonperfusion in screening, initial evaluation, treatment, and follow-up of progressive ischemic retinopathy such as DR and RVO.

Shin Y.U., Lee B.R., Kim S., Lee W.J. A novel noninvasive detection method for retinal nonperfusion using confocal red-free imaging. Ophthalmology. 2012;119(7):1447-54.
doi: 10.1016/j.ophtha.2012.01.036.