Abstract
Purpose :
To investigate the change of choroidal volume (CV) in the macular region after acute intraocular pressure (IOP) elevation in patients with occludable angles.
Methods :
A dark room prone provocative test (DRPPT) for was applied to angle-closure suspects. A swept-source optical coherence tomography was performed in the individuals before the DRPPT was started and within 5 minutes after the 2-hour DRPPT. 3D image data sets of the macular choroid were obtained using a 6×6 mm raster scan protocol. It post-processed using the Amira software. The choroid was manually outlined every 10 images by one experienced ophthalmologist. A cubic spline interpolation was applied to obtain a smooth continuous line in the X-axis, and then in the Y-axis, to get a smooth continuous plane. A 3×3 mm2 square area centered on the fovea was chosen for analysis, which was further divided to 5 regions (central, superior, inferior, nasal and temporal) (Fig1). CV was computed in a masked manner in each region and as a whole at baseline and after IOP rise using MATLAB software.
Results :
The study enrolled 30 eyes of 16 individuals with a mean age of 61.8±8.1 years. IOP increased from 18.1±2.0mmHg at baseline to 27.4±8.7mmHg after the DRPPT. CV showed a significant (P<0.05) decrease after the DRPPT in each sub-region and as a whole (Tab1.) The change of CV was largest in the central region (-5.1±6.7%), followed by the nasal region (-4.6±6.8%), inferior region (-4.1±6.0%), temporal region (-3.7±5.6%), and superior region (-1.8±5.0%). In multivariate analysis, the change in CV was significantly associated with the rise in IOP and / or with the baseline CV at the same location, but not associated with age, gender, axial length, or anterior chamber depth.
Conclusions :
CV in the macular region decreased parallel to an acute increase in IOP in individuals 2 hours after the DRPPT, with the changes being most marked in the central and nasal regions of the macula.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.