PURPOSE: This study aimed to examine the effect of head-down tilt (HDT) on vascular autoregulation in different age groups anddetermine its effects on intraocular pressure (IOP) and central corneal thickness (CCT).METHODS: Included were 43 eyes of 23 men. The optic
nerve head and parafoveal vascular densities were measured by optical coherence tomography angiography before and after 20 min 10 HDT. Also, the study comprised an examination of theIOP and CCT in a subset of 8 participants (14 eyes) in the sitting position and during 15 min of 10 HDT.RESULTS:
Grid-based inside disc all-vessel density (GBID) was statistically significantly lower after the HDT test in subjects under 30 yr (1.26). Whole image and peripapillary capillary vessel density (WICVD, PCVD), and whole image and peripapillary all-vessel density (WIAVD, PAVD) were significantly
higher after the HDT test in subjects ages 3039 yr (1.34, 2.16, 1.05, 1.72, respectively). Inside disc capillary, all-vessel density (IDCVD, IDAVD) and GBID were significantly higher after HDT in subjects over 40 yr (2.48, 2.15, 1.52, respectively). In a subset of eight participants, IOP was
significantly higher (3.7 mmHg) and CCT was unchanged after 15 min of HDT.CONCLUSION: Our study showed that simulated microgravity induced optic nerve head vessel density at the inside disc area, especially in persons over 40 years. In addition, IOP was increased by HDT, although
no change in CCT was observed.zelbaykal B, retmenolu G, Tunez H. Ocular outcomes in healthy subjects undergoing a short-term head-down tilt test. Aerosp Med Hum Perform. 2021; 92(8):619626.
Correlation of central corneal thickness and optic nerve head topography in patients with primary open-angle glaucoma
