Relationship of Geographic Altitude with Foveal Avascular Zone Metrics and Vascular Density Values Assessed by OCT Angiography

Acosta C.; Gloria J.M.; Lavaque A.; García V.; Torres E.; Agüero C.; Ríos M.Á.; Buendía M.; Jiménez J.M.; Lechuga R.; Sardi C.; Sánchez J.G.; Restrepo C.A. · Ophthalmology Retina (2020) · DOI: 10.1016/j.oret.2019.10.017

Resumen

Purpose: To evaluate variations in vascular density (VD) and foveal avascular zone (FAZ) metrics in relation to geographic altitude in healthy subjects from 6 Latin American cities. Design: Cross-sectional study. Participants: Healthy volunteers from 6 Latin American cities. Methods: One hundred eighty-five volunteers were recruited over a 3-month period. The RTVue-XR Avanti system (Optovue, Inc, Fremont, CA) was used along with split-spectrum amplitude-decorrelation angiography (SSADA) software 7.1 to obtain OCT angiography (OCTA) images from fovea-centered 3 × 3-mm2 and 6 × 6-mm2 angioscans for both the superficial and deep capillary plexuses (SCP and DCP, respectively). FAZ measurements were performed in a full retina slab based on the full retina vasculature using OCT angiograms. Analyses of variance were performed for all variables, and P < 0.05 indicated statistical significance. Main Outcome Measures: Retinal SCP and DCP VD; FAZ area, perimeter, and parafoveal density at 300 μm (FD-300). Results: Three hundred seventy eyes of 185 participants (71 males and 114 females; mean age, 39.09±15.06 years; age range, 20–80 years) were assessed. The mean VD in the SCP and DCP was 46.94% (±3.11%) and 52.48% (±3.14%), respectively, with 3 × 3-mm2 scans and 50.62% (±3.13%) and 52.87% (±5.5%), respectively, with 6 × 6-mm2 scans. Mean FAZ area, perimeter, and FD-300 were 0.31 (± 0.11 mm2), 2.18 (± 0.43 mm), and 51.44 (± 3.64%), respectively. Mean SCP VD values in 3 × 3-mm2 scans were significantly higher and lower in La Paz and Lima, respectively, compared to those in the other cities (P = 0.001). VD in the 6 × 6 mm2 SCP scans, the DCP (all scans), and FAZ metrics showed no significant differences. Conclusions: VD showed a direct relationship with geographic altitude in SCP 3 × 3-mm2 scans in this group of healthy Hispanic volunteers. These findings indicate that geographic altitude should be accounted for when performing retinal OCTA evaluation of VD values.