OCT Angiography Changes in the 3 Parafoveal Retinal Plexuses in Response to Hyperoxia

Abstract

Purpose Use projection-resolved OCT angiography to investigate the autoregulatory response in the 3 parafoveal retinal plexuses under hyperoxia. Design Prospective cohort study. Participants Nine eyes from 9 healthy participants. Methods One eye from each participant was scanned using a commercial spectral-domain OCT system. Two repeated macular scans (3 × 3 mm2) were acquired at baseline and during oxygen breathing. The split-spectrum amplitude-decorrelation algorithm was used to detect blood flow. The projection-resolved algorithm was used to suppress projection artifacts and resolve blood flow in 3 distinct parafoveal plexuses. The Wilcoxon signed-rank test was used to compare baseline and hyperoxic parameters. The coefficient of variation, intraclass correlation coefficient, and pooled standard deviation were used to assess the reliability of OCT angiography measurements. Main Outcome Measures Flow index and vessel density were calculated from the en face angiograms of each of the 3 plexuses, as well as from the all-plexus inner retinal slab. Results Hyperoxia induced significant reduction in the flow index (−11%) and vessel density (−7.8%) of only the deep capillary plexus (P < 0.001) and in the flow index of the all-plexus slab (P = 0.015). The flow index also decreased in the intermediate capillary plexus and the superficial vascular complex, but these changes were small and not statistically significant. The projection-resolved OCT angiography showed good within-session baseline repeatability (coefficient of variation, 0.8%–5.2%; intraclass correlation coefficient, 0.93–0.98) in all parameters. Relatively large between-day response reproducibility was observed (pooled standard deviation, 1.7%–9.4%). Conclusions Projection-resolved OCT angiography was able to show that the retinal autoregulatory response to hyperoxia affects only the deep capillary plexus, but not the intermediate capillary plexus or superficial vascular complex.

Early retinal microvascular abnormalities in patients with chronic kidney disease

“…43 The plexuses may respond differently to systemic condition alteration, such as changes in BP and oxygenation, or to retinal functional hyperemia evoked by a flickering light stimulus. [44][45][46] In our study, antihypertensive drugs and eGFR were associated with vessel density in SVP, but not in DVP. On the contrary, smoking was associated with vessel density in DVP, but not in SVP.…”

“…Each capillary plexus has different anatomical structures and may have its own autoregulation . The plexuses may respond differently to systemic condition alteration, such as changes in BP and oxygenation, or to retinal functional hyperemia evoked by a flickering light stimulus . In our study, anti‐hypertensive drugs and eGFR were associated with vessel density in SVP, but not in DVP.…”

Projection-Resolved Optical Coherence Tomographic Angiography of Retinal Plexuses in Retinitis Pigmentosa

“…57,59,60 The findings of the recent hyperoxia experiments suggest that deeper retinal plexuses, especially the DCP, contribute to the nourishment of outer retinal layers, along with choroidal circulation. 39 Thus, we expected that outer retinal degeneration will cause a decrease in metabolic demand, and consequently secondary vascular remodeling and attenuation. This hypothesis was further supported by the strong correlation between perifoveal changes in the VD in the DCP and ICP, and the perifoveal outer retinal thickness in RP patients with no history of CME.…”

“…Our group has recently developed projection-resolved OCTA (PR-OCTA) algorithm 33,34 to significantly suppress projection artifacts, allowing for proper segmentation of retinal circulation, and in turn more reliable visualization and quantification of microvasculature. [35][36][37][38][39][40][41][42][43][44][45] In this study, we aim to characterize the alterations in perfusion in all three retinal plexuses, as well as the relationship between vascular and structural changes in RP patients.…”

Characterization of the Three Distinct Retinal Capillary Plexuses Using Optical Coherence Tomography Angiography in Myopic Eyes

“…[19][20][21][22] Changes in each of the three distinct capillary plexuses have been described for specific conditions, such as diabetic retinopathy (DR), hyperoxia, and dark adaptation, and it has been demonstrated that each vascular layer undergoes independent changes. [23][24][25][26] But, these studies lack definitive evidence for segmentation.…”