Peripapillary choroidal vascular layers: the Beijing Eye Study

Purpose: To assess thickness and associations of the peripapillary choroidal layers.

Methods: The population-based Beijing Eye Study included 3468 participants with an age of 50+ years. Using spectral-domain optical coherence tomography, we measured the large vessel layer (LVL) and small-to-medium vessel layer (SMVL) of the peripapillary choroid in a circular scan with a diameter of 3.4 mm around the optic nerve head centre at eight locations equidistant (45°) to each other. The ratio of SMVL thickness to LVL thickness was calculated.

Results: Measurements were available for 3000 (86.5%) study participants (mean age: 64.4 ± 9.6 years; range: 50-93 years). SMVL (mean thickness: 31 ± 7 μm; range: 17-70 μm) and LVL (103 ± 48 μm; range: 9-313 μm) were thickest superiorly, followed by the temporal region, nasal region, and inferior region. Thicker SMVL was associated (regression coefficient r: 0.33) with younger age (p < 0.001; standardized regression coefficient β: -0.26), higher cognitive function (p = 0.02; β: 0.05), shorter axial length (p < 0.001; β: -0.12), thicker lens (p < 0.001; β: 0.07), smaller disc area (p < 0.001; β: -0.08), smaller parapapillary β/γ zone (p < 0.001; β: -0.10) and lower prevalence of angle-closure glaucoma (p = 0.04; β: -0.04). Thicker LVL thickness was correlated (r: 0.45) with younger age (p < 0.001; β: -0.34) and higher cognitive function (p = 0.01; β: 0.05), shorter axial length (p < 0.001; β: -0.09)), thicker lens (p = 0.009; β: 0.06), smaller disc area (p < 0.001; β: -0.09), smaller parapapillary alpha zone (p = 0.04; β: -0.04), smaller β/γ zone (p < 0.001; β: -0.14) and lower prevalence of angle-closure glaucoma (p = 0.057; β: -0.04). A higher SMVL-to-LVL thickness ratio was related with older age (p < 0.001; β: 0.36), longer axial length (p < 0.001; β: 0.09), lower best-corrected visual acuity (BCVA) (p = 0.002; β: 0.07), larger optic disc area (p < 0.001; β: 0.10) and larger β/γ zone (p < 0.001; β: 0.19).

Conclusion: Small-to-medium vessel layer (SMVL) and LVL, thickest superiorly and thinnest inferiorly, increased with younger age and higher cognitive function after adjusting for axial length and prevalence of angle-closure glaucoma. With older age, longer axial length, larger optic disc area and larger β zone, LVL decreased more than SMVL in thickness. The association between thicker peripapillary choroidal thickness and better cognitive function may deserve further attention.