Abstract
Purpose: :
Others have reported the measurement of choroidal thickness measurement by optical coherence tomography (OCT), however the diurnal fluctuation of the choroid is still poorly understood. We investigated the diurnal change of the subfoveal choroidal thickness (SFCT) and its relation to systemic factors in normal subjects.
Methods: :
Twenty eyes of 10 healthy subjects were enrolled in Osaka University Hospital. SFCT, intraocular pressure (IOP), systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse (PS) were measured every 3 hours throughout a 24-hour period, and diurnal change of mean arterial pressure (MAP) and mean ocular perfusion pressure (MOPP) were also calculated. The prototype high penetration OCT (HP-OCT, Swept-source) was used for imaging the choroid and measuring SFCT. SFCT was measured by three masked raters. Each SFCT of every 3 hours was evaluated, and analyzed to see its relation to circulation parameters. Refractive error (RE), axial length (AL) and central corneal thickness (CCT) were also measured at baseline.
Results: :
Mean age was 37.5 ± 8.4 years, mean RE -4.6 ± 2.2 diopter, mean AL 25.8 ± 0.9 mm, and mean CCT was 0.514 ± 0.035 mm. Total mean SFCT was 256 ± 74 microns. Mean SFCT at 9 PM (248 ± 73 microns) was thinnest and mean SFCT at 3 AM (264 ± 77 microns) was thickest. SFCT at 9 PM was significantly thinner than that at 3 AM (P<0.01), 6AM (P<0.01), 9 AM (P<0.01) and 12 AM (P<0.01). SFCT at 3 AM was significantly thicker than that at 0AM (P<0.05), 3 PM (P<0.01), 6 PM (P<0.01) and 9 PM (P<0.01) by Tukey-Kramer’s test for multiple comparisons. SFCT showed a significant negative correlation with SBP (P < 0.01). There were no significant differences between SFCT and other factors such as IOP (P=0.95), DBP (P= 0.66), MAP (P=0.14), PS (P= 0.33) and MOPP (P=0.08). Nocturnal DBP increased gradually between 9 PM and 3 AM, which was similar to the fluctuation of the SFCT. Peak time of PS was 9 PM, which was the same time of the thinnest SFCT.
Conclusions: :
Nocturnal subfoveal choroidal thickness was increased. Fluctuation of the choroidal thickness seems to be related to some circulative parameters.
Keywords: choroid • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical