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Diabetic Retinopathy Severity and Peripheral Lesions Are Associated with Nonperfusion on Ultrawide Field Angiography
Paolo S Silva1, Amanda J Dela Cruz2, Migil G Ledesma2
1Beetham Eye Institute, Joslin Diabetes Center, Boston, Massachusetts; Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts; Teleophthalmology and Image Reading Center, Philippine Eye Research Institute, National Institutes of Health, University of the Philippines, Manila, Philippines.
Purpose:
To assess whether the presence of peripheral nonperfusion on ultrawide field (UWF) fluorescein angiography (FA) is associated with diabetic retinopathy (DR) severity and the presence of predominantly peripheral lesions (PPLs).
Design:
Single-site, cross-sectional, retrospective study.
Participants:
Sixty-eight eyes of 37 diabetic subjects with or without DR and no history of prior panretinal laser photocoagulation.
Methods:
Both 200° UWF images and UWF FA images were acquired at the same visit. Early Treatment Diabetic Retinopathy Study (ETDRS) templates were overlaid digitally based on disc and macula location onto stereographically projected UWF images. Images were evaluated for the presence of PPLs, defined as more than 50% of the graded lesion located outside the ETDRS field in each of the 5 extended fields. The UWF-FA images were evaluated by 2 masked, independent graders for extent of retinal nonperfusion area (NPA) and nonperfusion index (NPI; nonperfused/total gradable area).
Main Outcome Measures:
Association of NPA and NPI with DR severity and presence of PPLs.
Results:
Distribution of DR severity was as follows: no DR, 8.8% eyes; mild nonproliferative DR (NPDR), 17.6%; moderate NPDR, 32.4%; severe NPDR, 17.6%; proliferative DR (PDR), 19.1%; and high-risk PDR, 4.4%; with PPL present in 61.8%. There was strong intragrader (r = 0.95) and intergrader (r = 0.86) agreement for NPA. Presence of PPLs was associated with increased NPA (191.8 mm(2) vs. 306.1 mm(2); P = 0.0019) and NPI (0.25 vs. 0.43; P = 0.0003). These relationships remained significant after adjusting for DR severity and diabetes duration. In eyes without PDR (n = 52), increasing NPA and NPI was associated with worsening DR (NPA, P = 0.001; NPI, P = 0.0003). NPA and NPI were not associated with clinically significant macular edema (NPA, P = 0.99; NPI, P = 0.67), nor correlated with visual acuity (NPA, r = 0.14, P = 0.23; NPI, r = 0.24, P = 0.05).
Conclusions:
Following a standardized protocol, the evaluation of UWF FA for NPA and NPI is reproducible. Both parameters are correlated highly with the presence of PPLs and DR severity. Given that the presence and extent of PPLs have been associated with increased risks of DR progression, the clinical identification of PPLs may reflect closely the extent of nonperfusion and ischemia, thus accounting for the increased risk of progression.
