Evaluation of Choroidal Thickness, Intraocular Pressure, and Serum Osmolality After the Water Drinking Test in Eyes With Primary Angle Closure.
OBJECTIVE
We evaluated changes in choroidal thickness (ChT), IOP, ocular biometry, and serum osmolality after the water drinking test (WDT) in subjects with previous acute primary angle closure (APAC) and primary angle closure glaucoma (PACG).


METHODS
We evaluated 38 subjects, including 21 with APAC and 17 with PACG. Each subject underwent IOP measurement, A-scan biometry, spectral domain-optical coherence tomography (SDOCT), anterior segment-optical coherence tomography (ASOCT), and osmolality measurements at baseline, 30, and 60 minutes after consuming at least 10 mL/kg of water. The ChT at the macula was measured from SDOCT images using the 7-line scan protocol. The fellow-eyes of APAC (FE-APAC) were compared to eyes with PACG.


RESULTS
The mean age ± SD of the study subjects was 62.8 ± 8.6 years and 21 (55.3%) were females. At baseline, serum osmolality was significantly lower (P < 0.001) in the FE-APAC group, whereas ChT was similar in both groups (P = 0.56). At 30 minutes after WDT, both groups demonstrated a significant increase in IOP (FE-APAC, 3.0 [95% confidence interval {CI}, 1.52, 4.48] mm Hg; PACG, 5.06 [95% CI, 3.68, 6.26] mm Hg; P < 0.001 for both) and decrease in serum osmolality (P < 0.001 for both), but no significant change in ChT. The magnitude of change in IOP was significantly greater in PACG eyes (P = 0.04). After multivariate analysis, a lower mean baseline serum osmolality (β = -0.44, P = 0.003) was associated with a greater change in ChT at 30 minutes after WDT.


CONCLUSIONS
The increase in IOP after WDT was higher in PACG eyes compared to FE-APAC; however, the latter had lower serum osmolality at baseline. Change in mean ChT following WDT was associated with a lower baseline serum osmolality.
Singapore Eye Research Institute, Singapore 2Duke-NUS Graduate Medical School, Singapore 3Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Monisha E
ME
Nongpiur
Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Valencia H X
VH
Foo
Singapore Eye Research Institute, Singapore.
John Mark
JM
de Leon
Singapore Eye Research Institute, Singapore 2Duke-NUS Graduate Medical School, Singapore 3Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Mani
M
Baskaran
Singapore Eye Research Institute, Singapore.
Tin A
TA
Tun
Singapore National Eye Centre, Singapore.
Rahat
R
Husain
Singapore National Eye Centre, Singapore.
Shamira A
SA
Perera
Singapore Eye Research Institute, Singapore 3Yong Loo Lin School of Medicine, National University of Singapore, Singapore 4Singapore National Eye Centre, Singapore.
Tin
T
Aung
D000368:Aged; D002829:Choroid / Q000473:pathology*; D060766:Drinking Water; D005260:Female; D005500:Follow-Up Studies; D015812:Glaucoma, Angle-Closure / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D011446:Prospective Studies; D041623:Tomography, Optical Coherence
D060766:Drinking Water