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Influence of body position and time of day on ocular rhythms

Ross A, Ostrin LA

Scientific reports, 2025

23 participants · 4 citations

Abstract

To determine the influence of time of day and body position on axial length, microvasculature, and intraocular pressure (IOP), participants (N = 23, ages 22-46 years) were enrolled in four 4-hour experimental sessions, which varied by time of day (morning or night) and body position (upright or supine). Blood pressure, heart rate, IOP, biometry, and optical coherence tomography (OCT) and OCT angiography (OCTA) imaging were performed every 2 h. For supine sessions, IOP was also measured 10 min after position changed to upright. When upright for 4 h in the morning, axial length increased 10.0 ± 2.8 μm (P = 0.005). When supine in the morning, axial length decreased 8.7 ± 2.2 μm (P 0.05 for all). In conclusion, body position and time of day influence axial length, choroidal thickness, and IOP, indicating that extrinsic factors work in conjunction with diurnal factors to mediate ocular rhythms.

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