Abstract
This study aimed to investigate changes in Schlemm’s canal, intraocular pressure and ocular blood circulation following the activation of the sympathetic nervous system. Twenty healthy volunteers were enrolled in this study. The cold pressor test (CPT) was adopted. Cross-sectional area of Schlemm’s canal (SCAR), superficial and deep retinal vessel densities (s-RVD;d-RVD), pupil diameter (PD), intraocular pressure (IOP), mean ocular perfusion pressure (MOPP) and heart rate variability (HRV) were measured at three time-points: baseline (T0) and 5 min (T1) and 10 min (T2) after the CPT. After cold stimulation, LF/HF index (the ratio of low frenquency and high frenquency) increased significantly. IOP decreased from 16.9 ± 1.9 mmHg at baseline to 16.4 ± 2.7 mmHg at T1 and to 15.2 ± 2.7 mmHg at T2. The nasal cross-sectional area of SCAR (SCAR-n) increased from 6283.9 ± 2696.2 µm2 at baseline to 8392.9 ± 3258.7 µm2 at T1 and to 10422.0 ± 3643.8 µm2 at T2. The temporal cross-sectional area of SCAR (SCAR-t) increased from 6414.5 ± 2218.7 µm2 at baseline to 8610.8 ± 2317.1 µm2 at T1 and to 11544.0 ± 4129.2 µm2 at T2. The expansion of Schlemm’s canal was observed after the CPT might be caused by sympathetic nerve stimulation, subsequently leading to decreased IOP.
Highlights
This study aimed to investigate changes in Schlemm’s canal, intraocular pressure and ocular blood circulation following the activation of the sympathetic nervous system
Participants’ mean age was 26.75 ± 3.3 years, mean best corrected visual acuity (BCVA) was 0.98 ± 0.06 and mean RE was −2.14 ± 2.01 diopter
intraocular pressure (IOP) changed from 16.9 ± 1.9 mmHg at T0 to 16.4 ± 2.7 mmHg at T1 and further decreased to 15.2 ± 2.7 mmHg at T2, post-cold pressor test (CPT)
Summary
This study aimed to investigate changes in Schlemm’s canal, intraocular pressure and ocular blood circulation following the activation of the sympathetic nervous system. Cross-sectional area of Schlemm’s canal (SCAR), superficial and deep retinal vessel densities (s-RVD;d-RVD), pupil diameter (PD), intraocular pressure (IOP), mean ocular perfusion pressure (MOPP) and heart rate variability (HRV) were measured at three time-points: baseline (T0) and 5 min (T1) and 10 min (T2) after the CPT. The expansion of Schlemm’s canal was observed after the CPT might be caused by sympathetic nerve stimulation, subsequently leading to decreased IOP. The intraocular pressure and ocular blood circulation were mainly controlled by the sympathetic nervous system[2,3].
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