Aim To evaluate the association between retinal capillary non-perfusion and diabetic retinopathy (DR) severity using optical coherence tomography-based microangiography (OMAG).
Methods 33 patients (51 eyes) with a history of diabetes underwent imaging with a 68 kHz Cirrus-5000 spectral domain OMAG prototype. Demographic and clinical characteristics were collected. The perfusion index (PI) was defined as per cent coverage of area by retinal vessels with flow, measured within a minimum of 6.8×6.8 mm2 OMAG scan. The PI in each ETDRS zone was analysed using an automated algorithm. Univariate and multivariate analyses were used to determine the degree of association between PI and DR severity.
Results 51 eyes with different DR severities were imaged. More severe DR was significantly associated with lower PI after adjusting for logarithm of the minimum angle of resolution best-corrected visual acuity, hyperlipidaemia, diabetes type and ETDRS ring in a multivariate mixed linear model. Compared with the none–mild non-proliferative diabetic retinopathy (NPDR) group, the moderate–severe NPDR group had 2.7 lower PI (p=0.03) and proliferative DR group had 4.3 lower PI (p=0.003). All ETDRS zones except for the foveal centre showed inverse associations between PI and DR severity (p values<0.001 to 0.862).
Conclusions A statistically significant inverse association exists between PI and DR severity. Our study suggests that PI may become a useful biomarker in evaluating and following the progression of DR.
- Diagnostic tests/Investigation
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Contributors ADL and AYL contributed equally and should be considered as co-first authors. Concept and design: QZ, CSL, RKW and AYL. Analysis and interpretation: ADL, CSL, AYL, QZ, RKW, KAR and JK. Writing the article: AYL, CSL, ADL and KAR. Data collection: ADL, CSL, AYL, QZ, RKW, JK and KAR. Literature search: ADL, CSL, AYL and KAR.
Funding This work was supported in part by research grants from the Carl Zeiss Meditec (Dublin, California), the National Eye Institute (R01EY024158, K23EY024921), an unrestricted grant from Research to Prevent Blindness and the Department of Bioengineering at the University of Washington.
Disclaimer The content is solely the responsibility of the authors and does not necessarily represent the views of the grant-giving bodies. All authors had access to clinical data.
Competing interests RW received research support from Carl Zeiss Meditec and co-owns a patent that is related to the subject matter discussed in this manuscript with Oregon Health & Science University.
Ethics approval This study was approved by the Institutional Review Board of the University of Washington and was in adherence with the tenets of the Declaration of Helsinki and the Health Insurance Portability and Accountability Act.
Provenance and peer review Not commissioned; externally peer reviewed.