Abstract
Purpose :
Though animal models have been extensively used to study emmetropization, information on retinal microvasculature and its relationship with refractive error are currently limited. The study aim was to characterize the retinal microvasculature of juvenile rhesus monkeys with a range of experimentally induced refractive errors using optical coherence tomography angiography (OCTA).
Methods :
Refractive error was experimentally induced in 18 rhesus monkeys using a combination of dim light and lenses or diffusers in the right eye from the age of 15 to 150 days, followed by 150 days of recovery. At 347 ± 13 days, measurements were collected, including spherical equivalent refraction (SER), axial length (AL), and OCT (30 degrees) and OCTA (15×15 degrees) macular scans (Spectralis, Heidelberg). Superficial and deep vascular complexes (SVC and DVC) were extracted from OCTA scans. Magnification-corrected metrics included foveal avascular zone area (FAZA) measured at DVC, retinal thickness in 1-mm diameter and 1.5- and 2-mm annuli, and perfusion density of the SVC and DVC (after projection artifact removal) in a 2-mm diameter and 3- and 4-mm annuli, centered at the fovea. Relationships between measurements were studied using Pearson correlation.
Results :
Mean SER and AL were 0.78 ± 4.02 D (-7.12 to +7.13 D) and 17.96 ± 1.08 mm (16.41 to 19.93 mm), respectively. Mean perfusion density of SVC and DVC were 0.38 ± 0.05, 0.42 ± 0.05, 0.42 ± 0.05 and 0.50 ± 0.03, 0.48 ± 0.03, 0.42 ± 0.05, in three zones, respectively. Retinal thickness and SER were correlated in the 1.5 -and 2-mm annuli (r = 0.64, P = 0.004; r = 0.68, P = 0.002) but not in the central 1 mm (P = 0.06), showing decreased retinal thickness with increasing myopia. Perfusion density of the SVC in 3- and 4-mm annuli were significantly correlated with AL (P ≤ 0.01 for both) and SER (P < 0.05 for both), whereas DVC perfusion density did not correlate with AL or SER (P > 0.05 for both). FAZA at DVC correlated with age and 1-mm retinal thickness (P < 0.05 for both).
Conclusions :
Parafoveal retinal thickness decreased with increasing myopia in juvenile rhesus monkeys. Increasing axial length and myopia were associated with a decrease in perfusion density of the superficial vascular complex. These findings could be indicative of alterations in microvasculature surrounding the fovea with increasing myopic refraction.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.