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  • Which OCTA Scanning Protocol Is Best for PDR and NPDR?

    By Lynda Seminara
    Selected By: Richard K. Parrish II, MD
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    Journal Highlights

    American Journal of Ophthalmology, July 2020

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    Although optical coherence tomog­raphy angiography (OCTA) can help detect microvascular changes indicative of diabetic retinopathy (DR), stud­ies have failed to establish a protocol that optimally balances scan area and lesion detection and also works well in a busy clinical setting. Zhu et al. recently compared OCTA scan protocols; they found that 15×9-mm Montage imaging was significantly better than 6×6-mm Angio imaging for detecting DR lesions (with the exception of microaneu­rysms). However, they also found that 12×12-mm Angio scanning centered on the fovea and optic disc was compara­ble to 15×9-mm Montage imaging for discerning lesions without sacrificing sensitivity or speed.

    For this study, the authors recruited 119 patients (176 scanned eyes) with proliferative DR (PDR; n = 80), non­proliferative DR (NPDR; n = 73), and diabetes mellitus without DR (n = 23). Eyes were imaged with swept-source (SS)-OCTA and multiple scan proto­cols in the following order: 3×3-mm Angio centered on the fovea; 6×6-mm Angio centered on the fovea and optic disc; 15×9-mm Montage; and 12×12-mm Angio centered on the fovea and optic disc.

    Two ophthalmologists independently assessed the images for DR lesions, including microaneurysms, intraretinal microvascular abnormali­ties, neovascularization, nonperfusion, venous looping, and hard exudates.

    Results were as follows:

    • For neovascularization in the optic disc and elsewhere, the detection rate with 6×6-mm Angio centered on the fovea was approximately half that of 15×9-mm Montage (17.6% vs. 34.6%, respectively; p < .05).
    • With 6×6-mm Angio centered on the fovea and optic disc, the rate was roughly two-thirds that of 15×9-mm Montage (26.1% vs. 36.2%, respectively; p < .05).
    • In detecting microaneurysms, 6×6-mm Angio centered on the fovea and the 6×6-mm Angio scan combina­tion outperformed Montage imaging (85.2% vs. 79.0% and 84.8% vs. 79.0%, respectively; both p < .05).
    • The 12×12-mm Angio images cen­tered on the fovea and optic disc had detection rates comparable to those of 15×9-mm Montage images for all DR lesions (p > .05); however, the rates for nonperfusion and neovascularization were slightly higher with Montage images in patients who received both scans.

    These findings support the use of widefield SS-OCTA for distinguishing PDR from NPDR, the authors said. They suggested that 12×12-mm Angio scans centered on the fovea and optic disc are a practical alternative to Mon­tage imaging in busy clinical practices.

    The original article can be found here.