Assessment of choroidal thickness and volume during the water drinking test by swept-source optical coherence tomography.

OBJECTIVE To evaluate changes in peripapillary and macular choroidal thickness and volume after the water-drinking test (WDT) using swept-source optical coherence tomography (SS OCT). DESIGN Prospective, cross-sectional, observational study. PARTICIPANTS Fifty-six eyes of 28 healthy volunteers. METHODS Participants underwent a 3-dimensional optic disc and macula scanning protocol with a prototype SS OCT (Topcon, Inc., Tokyo, Japan) at baseline and 15, 30, 45, and 120 minutes after the start of the WDT. The WDT consisted of drinking 1000 ml of water within 5 minutes. Objective measurements of the choroid were obtained with automated segmentation of the choroidal boundaries. MAIN OUTCOME MEASURES Choroidal thickness and volume. RESULTS Mean age ± standard deviation of participants was 35.6 ± 9.1 years. Intraocular pressure (IOP) increased from 14.9 ± 2.7 mmHg at baseline to a peak of 16.8 ± 3.0 mmHg 15 minutes after the WDT (P < 0.001). Mean baseline choroidal thickness and volume were 181.3 ± 50.8 μm and 6.19 ± 1.80 mm(3), respectively, at the optic disc and 217.4 ± 43.6 μm and 7.83 ± 1.55 mm(3), respectively, at the macula. After the WDT, peripapillary and macular choroidal thickness increased by a maximum of 5.7% (P<0.001) and 4.3% (P<0.001), respectively. Choroidal volumes increased by 6.4% (P<0.001) and 3.9% (P<0.001), respectively. There was no association between change in IOP and peripapillary (P = 0.27) or macular (P = 0.09) choroidal thickness. CONCLUSIONS Using automated segmentation of SS OCT measurements, significant increases in choroidal thickness and volume are observed after the WDT in healthy subjects.