Clinical and optical coherence tomography angiography-based risk factors for reduced retinal sensitivity in diabetic macular edema

Purpose To compare microperimetric retinal sensitivity (RS) and Optical Coherence tomography angiography (OCTA)derived perfusion metrics between eyes with diabetic macular edema (DME) and healthy controls, and to explore clinical and imaging parameters associated with lower RS within the diabetic cohort. Methods Prospective cross-sectional study of 38 diabetic eyes from 31 patients and 25 control eyes. All participants underwent microperimetry and OCTA on the same day. RS and OCTA-derived vessel metrics were assessed using a standard/general microperimetry pattern and clinician-defined customized subgrids targeting areas of suspected reduced perfusion in the deep vascular complex. Between-group differences were analyzed using linear mixed-effects models with patient identity as a random intercept to account for inter-eye correlation. Within the diabetic cohort, generalized linear mixed-effects models
were used to explore parameters associated with RS, including Best-corrected visual acuity (BCVA), anti-vascular endothelial growth factor (VEGF) treatment intensity, persistent intraretinal fluid, previous panretinal photocoagulation, cardial and
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cerebral comorbidity, Optical Coherence Tomography (OCT)-derived neuroretinal metrics, and OCTA-derived vessel metrics. Results Compared with healthy controls, diabetic eyes showed significantly lower general macular RS and altered OCTA-
derived perfusion metrics, particularly in the deep vascular complex. General macular RS was reduced by − 3.99 dB in diabetic eyes compared with controls (95% CI: −5.51 to − 2.48, p < 0.001). OCTA-derived vessel metrics showed moderate correlations with general RS. Localized OCTA-guided subgrids did not provide additional functional information beyond the standard/general microperimetry pattern. Within the diabetic cohort, worse BCVA, previous panretinal photocoagulation, and persistent intraretinal fluid were associated with lower RS in exploratory mixed-effects models. Cardio- and cerebrovascular comorbidity showed a non-significant tendency toward lower RS.
Conclusion Eyes with DME showed reduced retinal sensitivity and altered OCTA perfusion compared with healthy controls. Focal OCTA-guided subgrids did not improve functional assessment beyond the standard/general microperimetry pattern. Reduced general RS in treated DME appears to reflect multifactorial mechanisms, including visual function, residual exudative activity, prior retinal treatment.