Retinal capillary density loss in diabetic retinopathy is not uniform across eccentricities; the deep capillary plexus shows preferential midperipheral dropout, with capillary density loss reaching 45% at 9 mm from the fovea versus 25% in healthy eyes.
Key Findings
Results
Overall capillary density was significantly lower in diabetic retinopathy eyes compared to healthy eyes across all plexuses.
21 eyes with nonproliferative or early proliferative DR and 10 healthy eyes were examined
Adjusted difference in capillary density between DR and healthy eyes was -4.1% (P < 0.001)
Swept-source optical coherence tomography angiography (OCTA) was used for imaging
Multiple 3 × 3-mm OCTA scans were acquired forming a horizontal band extending from the fovea to 9 mm temporally
Capillary density was measured in each 0.1-mm sample within each capillary plexus and analyzed using a linear mixed-effects model
Results
Capillary density reduction in DR eyes was uniform regardless of eccentricity in the superficial and intermediate plexuses but increased toward the periphery specifically in the deep capillary plexus (DCP).
The group × plexus × eccentricity interaction was statistically significant (P < 0.001)
The superficial and intermediate plexuses showed no eccentricity-dependent difference in capillary density reduction between DR and healthy eyes
The deep capillary plexus demonstrated a progressively greater capillary density reduction with increasing distance from the fovea in DR eyes
This finding indicates a plexus-specific, region-dependent pattern of capillary loss
Results
In the deep capillary plexus, capillary density plateaued beyond 6 mm from the foveal center in healthy eyes but continued to decrease up to 9 mm in DR eyes.
Segmented regression analysis was used to identify the breakpoint in the eccentricity-CD relationship
In healthy eyes, DCP capillary density plateaued beyond 6 mm from the foveal center
In DR eyes, DCP capillary density continued to decrease up to 9 mm (the limit of the imaging field)
Midperipheral capillary density loss in the DCP reached 45% in DR eyes versus 25% in healthy eyes (P < 0.001)
Results
Capillary density decreased toward the temporal midperiphery in all capillary plexuses in both DR and healthy eyes.
The decreasing gradient of capillary density with increasing eccentricity was observed across all plexuses in both groups
This eccentricity-dependent decrease was present in the superficial, intermediate, and deep capillary plexuses
The imaging field extended from the fovea to 9 mm temporally, capturing the midperipheral retina
Discussion
The preferential midperipheral deep capillary plexus dropout was identified as a potential imaging marker of ischemia progression in diabetic retinopathy.
The DCP-specific, peripherally accentuated capillary loss pattern was not observed in the superficial or intermediate plexuses
The authors suggest this pattern 'could serve as an imaging marker of ischemia progression in diabetic retinopathy'
The study focused on nonproliferative or early proliferative DR, representing relatively early stages of the disease
The findings highlight a plexus-specific, region-dependent pattern of capillary loss in DR
What This Means
This research suggests that in people with diabetic retinopathy, the loss of tiny blood vessels (capillaries) in the retina is not evenly distributed across the eye. By using a specialized imaging technology called optical coherence tomography angiography (OCTA), researchers mapped capillary density from the center of the retina (the macula) out to the midperiphery — a region farther from the center that is often not examined in routine clinical practice. They found that while people with diabetic retinopathy had fewer capillaries overall compared to healthy individuals, the loss was especially severe in the midperipheral region of the deepest layer of retinal blood vessels, called the deep capillary plexus. In that region, capillary density was reduced by 45% in diabetic retinopathy patients compared to only 25% in healthy eyes.
This research suggests that different layers of retinal blood vessels are affected differently by diabetes, and that the outer edges of the retina — beyond the central area typically examined in clinical settings — may be particularly vulnerable. The deep capillary plexus in the midperiphery appears to lose blood vessels progressively in ways that the shallower layers do not. This pattern of peripheral, layer-specific capillary dropout may reflect how diabetic damage spreads through the retina over time.
The practical implication is that standard imaging focused only on the central retina may miss important signs of disease progression in diabetic retinopathy. This research suggests that extending retinal imaging into the midperiphery, particularly to assess the deep capillary layer, could help detect worsening ischemia (reduced blood flow) earlier and potentially serve as a marker to monitor how the disease is progressing in patients with diabetes.
Torres-Villaros H, Gaudric A, Dulière C, Erginay A, Lavia C, Le Boité H, et al.. (2026). Retinal Capillary Loss Is More Severe in the Midperiphery Than in the Macula in Eyes With Diabetic Retinopathy Compared to Healthy Eyes.. Translational vision science & technology. https://doi.org/10.1167/tvst.15.10.19