Imaging Biomarkers of Mesopic and Dark-Adapted Macular Functions in Eyes With Treatment-Naive Mild Diabetic Retinopathy

center dot PURPOSE: To investigate the relationship between imaging biomarkers and mesopic and dark-adapted (ie, scotopic) functions in patients with treatment-naive mild diabetic retinopathy (DR) and normal visual acuity. center dot DESIGN: Prospective cross-sectional study. center dot METHODS: In this study, 60 patients with treatment-naive mild DR (Early Treatment of Diabetic Retinopathy Study levels 20-35) and 30 healthy control subjects underwent microperimetry, structural optical coherence tomography (OCT), and OCT angiography (OCTA). center dot RESULTS: The foveal mesopic (22.4 +/- 4.5 dB and 25.8 +/- 2.0 dB, P =.005), parafoveal mesopic (23.2 +/- 3.8 and 25.8 +/- 1.9, P <.0001), and parafoveal dark-adapted (21.1 +/- 2.8 dB and 23.2 +/- 1.9 dB, P =.003) sensitivities were reduced in DR eyes. For foveal mesopic sensitivity, the regression analysis showed a significant topographic association with choriocapillaris flow deficits percentage (CC FD%; beta= -0.234, P =.046) and ellipsoid zone (EZ) normalized reflectivity (beta= 0.282, P =.048). Parafoveal mesopic sensitivity was significantly topographically associated with inner retinal thickness (beta= 0.253, P =.035), deep capillary plexus (DCP) vessel length density (VLD; beta= 0.542, P =.016), CC FD% (beta= -0.312, P =.032), and EZ normalized reflectivity (beta= 0.328, P =.031). Similarly, parafoveal dark-adapted sensitivity was topographically associated with inner retinal thickness (beta= 0.453, P =.021), DCP VLD (beta= 0.370, P =.030), CC FD% (beta= -0.282, P =.048), and EZ normalized reflectivity (beta= 0.295, P =.042). center dot CONCLUSIONS: In treatment-naive mild DR eyes, both rod and cone functions are affected and they are associated with both DCP and CC flow impairment, which suggests that a macular hypoperfusion at these levels might implicate a reduction in photoreceptor function. Normalized EZ reflectivity may be a valuable structural biomarker for assessing photoreceptor function in DR. (c) 2023 Elsevier Inc. All rights reserved.

Automated summary

This study investigated the relationship between imaging biomarkers and mesopic and dark-adapted functions in patients with treatment-naive mild diabetic retinopathy (DR) and normal visual acuity. The results showed that both rod and cone functions were affected in DR eyes, and they were associated with impairment in deep capillary plexus (DCP) and choriocapillaris (CC) flow. Normalized ellipsoid zone (EZ) reflectivity may be a valuable structural biomarker for assessing photoreceptor function in DR.