Abstract
Purpose: :
A preliminary study to investigate diurnal change in choroidal thickness and its relationship to intraocular pressure (IOP), axial length (AL), and blood pressure (BP).
Methods: :
The sample consisted of 3 healthy participants (mean age 27.7 ± 0.6 years) with refractive error less than ± 6.00 D sphere and/or ± 2.50 D cylinder, no ocular or systemic diseases and no medications. Measurements of choroidal thickness (Spectralis SD-OCT; Heidelberg Engineering), axial length (IOLMaster; Carl Zeiss Meditec), intraocular pressure and blood pressure, were recorded every 2 hours between 8am and 8pm. SD-OCT imaging used the standard macular volume scan protocol (1, 3, 6 mm ETDRS, 25 X 25) and RNFL thickness scan protocol. Choroidal thickness maps were produced for the macular and peripapillary regions. Three measurements were averaged for each time point.
Results: :
Diurnal variation was observed in all parameters. Over 12 hours the mean percentage variation in: peripapillary choroidal thickness was 10.0 ± 2.6%; foveal choroidal thickness was 15.0 ± 3.4%; IOP was 14.3%; systolic BP was 12.8 ± 2.9%(p= 0.48); diastolic BP was 16.8 ± 1.5%; axial length was 0.29 ± 0.21%; ocular perfusion pressure was 18.3 ± 3.5%. No significant correlation was observed between parameters. However, an antiphase relationship between foveal and peripapillary choroidal thickness was observed.
Conclusions: :
Choroidal thickness, IOP, BP and axial length, all demonstrated diurnal change, but did not appear to co-vary using a simple linear model.
Keywords: choroid • intraocular pressure