In Early Diabetic Retinopathy, Choriocapillaris Flow Insufficiency Accompanies Photoreceptor Damage

Among patients with diabetes mellitus type 1 (DM1), eyes with mild nonproliferative diabetic retinopathy (NPDR) have photoreceptor damage that is accompanied by choriocapillaris flow insufficiency, an observational cross-sectional study published in the British Journal of Ophthalmology shows.

Patients (n=40) with DM1 who have mild NPDR (n=28; mean age; 41.7 years; 50% men) or no sign of diabetic retinopathy (NoDR; n=12; mean age, 36.7 years; 58% men) and healthy controls (n=10; mean age 38.1 years; 30% men) were recruited in 2020 at the IRCCS-Bietti Foundation in Italy. Study participants underwent imaging using adaptive optics retinal camera and optical coherence tomography angiography (OCT-A). Ophthalmologic features were compared between groups.

Among the NPDR and NoDR groups, the noDR group were diagnosed with DM1 more recently (mean, 12.3 vs 21.4 years; P <.001) and tended to have lower glycated hemoglobin (mean, 6.9% vs 7.41%; P =.079) compared with NPDR, respectively.

In the parafoveal region, the 3 groups differed significantly for heterogeneity packing index (P <.001), linear dispersion index (P =.001), choriocapillaris flow deficits (P =.004), superficial capillary plexus perfusion density (P =.007), and deep capillary plexus perfusion density (P =.043). Among the DM1 cohorts, the NoDR group had significantly higher parafoveal heterogeneity packing index and lower capillary plexus perfusion density (both P <.05).

In the topographical analysis, all cone metrics (all P ≤.016) and OCTA parameters (all P ≤.032) differed significantly between the 3 groups. Among the DM1 groups, NoDR had lower temporal linear dispersion index and higher inferior heterogeneity packing index (both P <.05) and lower superior, inferior, temporal, and nasal choriocapillaris flow deficits (all P <.05).

In the NPDR group, cone density was significantly correlated with choriocapillaris flow deficits of the parafoveal, inferior, and temporal regions; with superficial capillary plexus perfusion density of the parafoveal, inferior, and temporal regions; and with deep capillary plexus perfusion density in the temporal region (all P ≤.049); cone packing was correlated with choriocapillaris flow deficits of the parafoveal, inferior, and nasal regions (all P ≤.017); and cone spacing was correlated with choriocapillaris flow deficits of the parafoveal and superior regions (both P ≤.035).

The major limitation of this study was the small sample size.

“By interpolating swept source-OCT-A and adaptive optics, we demonstrated that NPDR eyes showed microvascular hypoperfusion and impaired cone density, cone spacing, and cone packing arrangement. Importantly, the choriocapillaris ischemia and the increased retinal flow seem to be strongly correlated with photoreceptor damage,” the study authors explain. “The topographical analysis revealed that the temporal parafoveal sector is most sensitive to microvascular and photoreceptors impairment in NPDR.”

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.