Evaluation of Choroidal Thickness, Intraocular Pressure, and Serum Osmolality After the Water Drinking Test in Eyes With Primary Angle Closure

Comparison of intraocular pressure profiles during the water drinking test and the modified diurnal tension curve

OBJECTIVES

To compare intraocular pressure (IOP) during the water drinking test (WDT) and modified diurnal tension curve (mDTC) in open-angle glaucoma (OAG) patients, using multimodal, observer-masked tonometry.

METHODS

Open-angle glaucoma subjects were prospectively enroled, excluding those who had undergone glaucoma filtration or laser surgery. Two-hourly mDTC Goldmann applanation (GAT) and rebound tonometry (RT) was performed between 8:00 and 16:00, and every 15 min for 45 min after ingestion of 800mls of water. Blood pressure, heart rate, pupillometry measurements, and optical coherence tomography (AS-OCT) were also recorded.

RESULTS

Forty-two subjects' right eyes were included. 48% were using topical glaucoma medication. Mean baseline IOP was 14.9 ± 4.52 mmHg, with mean visual field mean deviation (±SD) -5.05 ± 5.45 dB. Strong association was found between maximum IOP during mDTC and WDT (r = 0.90, 95% CI 0.82-0.95 p < 0.0001) with agreement (mDTC-WDT) bias -0.82 mmHg, 95% LoA -1.46 to -0.18. During the WDT, mean systolic blood pressure (±SD) increased from 140.0 ± 20.0 to 153.3 ± 24.0 mmHg (p < 0.0001), mean heart rate ( ± SD) reduced from 69.5 ± 11.3 bpm to 63.6 ± 10.0 bpm (p < 0.0001), and temporal iridocorneal angle increased from 29.2 ± 6.0° to 29.6 ± 5.2° (p = 0.04).

CONCLUSION

This study presents repeated, observer-masked IOP data showing strong correlation between maximum IOP during mDTC and WDT using multimodal tonometry. This supports WDT as a meaningful alternative to mDTC when investigating diurnal IOP characteristics in clinic, with reduced time requirements and associated costs.

Assessment of the effects of myopic and hyperopic anisometropia on choroidal vascular structure in children using SS-OCTA

OBJECTIVE

To compare large- and medium-sized choroidal vascularity and the choriocapillaris (CC) flow area in children with different refractive errors using swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

Forty-two anisometropic children were enrolled and divided into hyperopic anisometropia (HA) and myopic anisometropia (MA) groups. SS-OCTA was performed to analyse choroidal vascularity. Mean choroidal thickness (CT), choroidal vascularity volume (CVV), choroidal vascularity index (CVI) and CC flow area were compared between the two eyes. The inter-ocular differences between the two groups were also determined.

RESULTS

Mean CT and CVV were highest in eyes with shorter axial lengths in both refractive groups, and the difference between the two eyes was positively correlated with the difference in axial length at the foveal region. Significant differences in the CVI in the MA group were only found in the parafoveal region. Inter-ocular differences in the CC were significantly reduced in eyes with longer axial lengths in the foveal and parafoveal regions of the HA and MA groups, respectively. Comparing inter-ocular differences, CC was significantly greater in the parafoveal region of the MA group than the HA group.

CONCLUSIONS

All layers of choroidal vasculature were thinner in eyes with longer axial lengths in all groups. The inter-ocular CC difference was greater in the MA than in the HA group, with similar differences in axial length. This suggests that both medium-to-large choroidal vascular and choroidal capillaries may play a role in myopia development.

IMI-The Dynamic Choroid: New Insights, Challenges, and Potential Significance for Human Myopia

The choroid is the richly vascular layer of the eye located between the sclera and Bruch's membrane. Early studies in animals, as well as more recent studies in humans, have demonstrated that the choroid is a dynamic, multifunctional structure, with its thickness directly and indirectly subject to modulation by a variety of physiologic and visual stimuli. In this review, the anatomy and function of the choroid are summarized and links between the choroid, eye growth regulation, and myopia, as demonstrated in animal models, discussed. Methods for quantifying choroidal thickness in the human eye and associated challenges are described, the literature examining choroidal changes in response to various visual stimuli and refractive error-related differences are summarized, and the potential implications of the latter for myopia are considered. This review also allowed for the reexamination of the hypothesis that short-term changes in choroidal thickness induced by pharmacologic, optical, or environmental stimuli are predictive of future long-term changes in axial elongation, and the speculation that short-term choroidal thickening can be used as a biomarker of treatment efficacy for myopia control therapies, with the general conclusion that current evidence is not sufficient.

Seasonal variations and climatic factors on acute primary angle-closure admission in southern China: a 5-year hospital-based retrospective study

PURPOSE

To delineate the seasonality of acute primary angle-closure (APAC) admission in a coastal city of southern China and its association with climatic factors.

METHODS

A total of 1155 Chinese subjects with principal diagnosis of APAC attack were recruited from 2012 to 2016, and their medical records were retrieved. Monthly climatic factors were obtained from the Meteorological Bureau of Shantou. Monthly and seasonal APAC admissions were compared, and its correlation with climatic factors was evaluated.

RESULTS

APAC admission was higher in female subjects (75.9%) with an overall mean age of 64.7 ± 9.3 years. APAC admission was highest in summer with the peak onset in June. The peak of APAC admission for female subjects aged ≤ 65 years was in June, and that for> 65 years was in July. The peak of APAC admission for male subjects aged > 65 years was in August. Precipitation was positively correlated with APAC admission rate for both aged ≤ 65 (β = 0.415, p = 0.001) and > 65 years old (β = 0.364, p = 0.004) female subjects. In contrast, surface temperature was positively correlated with APAC admission rate for male subjects aged > 65 years (β = 0.441, p < 0.001). No climatic factor was correlated with APAC admission rate for male subjects ≤ 65 years.

CONCLUSIONS

This study revealed the peak season of APAC admission in summer, and surface temperature and precipitation are the associated factors. Close monitoring of climate changes could help to reduce the incidence of APAC attack.

Retinal microvascular density modifications during the water drinking test

PURPOSE

The water drinking test (WDT) is a well-known stress test that increases intraocular pressure (IOP) momentarily and can indicate risk of glaucoma progression. This study focuses on correlating changes in the retinal microvascular plexus with the WDT in young healthy subjects.

METHODS

A total of 20 eyes of 20 healthy young subjects (mean age 24.37 ± 2.17 years) were included in this study. In our protocol, WDT consisted of drinking 1 L of water within 5 min. Outcome measures in this prospective observational study were mean arterial pressure (MAP), heart rate (HR), IOP, and retinal vessel density of both superficial and deep macular retina using optical coherence tomography angiography (OCTA), which were assessed before water ingestion and four times after at 15-min intervals. OCTA images were later quantified by fractal analysis (box counting [D_box]). One-way repeated measures analysis of variance (ANOVA) was used to assess the effects of WDT on each of the parameters.

RESULTS

The WDT resulted in significant peak changes of the following parameters compared to baseline: IOP: 15.63 ± 3.37 versus 18.38 ± 4.53 mmHg at 30 min, p < 0.001; HR: 75.74 ± 12.23 versus 64.95 ± 11.37 bpm at 15 min, p < 0.001; deep retinal vessel density 1.758 ± 0.14 versus 1.749 ± 0.16 at 15 min, p = 0.040.

CONCLUSIONS

Besides IOP elevation and systemic effects in HR, WDT is associated with temporary modifications of the deep vascular plexus in young healthy subjects.

Water-drinking Test and Pharmacologic Mydriasis as Provocative Tests in Primary Angle Closure Suspects

Purpose

To compare the water-drinking test (WDT) and pharmacologic mydriasis as provocative tests in patients with primary angle closure suspect (PACS).

Methods

This observational non-randomized comparative study evaluated changes in intraocular pressure (IOP) in 21 patients with PACS who underwent pharmacologic mydriasis and compared it with IOP changes in 26 patients given the WDT. Ocular biometric and anterior chamber parameters were also assessed. Tests were repeated on the same patient two weeks after performing laser peripheral iridotomy (LPI).

Results

The mean age ± standard deviation was 60 ± 7 and 57 ± 9 years in the mydriasis and WDT groups, respectively (P = 0.201). Before LPI, both provocative tests were associated with a significant increase in IOP (mydriasis: 15.1 ± 3.1 to 16.6 ± 3.5 mmHg, P = 0.025; WDT: 16.2 ± 2.8 to 18.5 ± 3.3 mmHg, P < 0.001). However, the IOP changes were not statistically different between groups (P = 0.102). After LPI, only the WDT group showed a continued significant IOP elevation after the test (mydriasis: 16.4 ± 3.3 to 16.7 ± 3.5 mmHg, P = 0.569; WDT: 14.9 ± 3.0 to 17.8 ± 4.1 mmHg, P < 0.001). The post-test IOP change was significantly greater in the WDT than in the mydriasis group (3.0 versus 0.3 mmHg, respectively; P = 0.002). Step-wise multiple regression analysis verified the type of provocative test as the only independent factor affecting the post-test IOP change after LPI (regression coefficient: 2.664; P = 0.002).

Conclusion

Pharmacologic mydriasis and the WDT had similar IOP elevation before LPI, but after LPI, IOP elevation was much greater in the WDT group.

Results for Water-drinking Test, before and after Laser Iridotomy, in Primary Angle-closure Suspects

SIGNIFICANCE

Intraocular pressure and ocular biometric changes were similar before and after laser iridotomy in response to the water-drinking test in a cohort of patients at risk of angle closure. The water-drinking test does not seem to be a good provocative test to determine which eyes would benefit from a laser iridotomy. Our data call into question the preoperative predictive value of this test.

PURPOSE

The aim of this study was to evaluate the effect of water-drinking test on intraocular pressure and ocular biometric parameters, before and after laser peripheral iridotomy, in patients with an occludable angle.

METHODS

Twenty-seven patients, who met the inclusion criteria and had at least 180 degrees of iridotrabecular apposition, underwent a complete eye examination followed by the measurement of ocular biometric (using LenStar LS-900; Haag-Streit AG, Koeniz, Switzerland) and anterior chamber parameters (using Pentacam HR; Oculus Optikgerate GmbH, Wetzlar, Germany). All the measurements were repeated 30 minutes after the water-drinking test. Two weeks after laser peripheral iridotomy, all the measurements were repeated both before and after the water-drinking test.

RESULTS

The mean ± SD of the age of the participants was 57 ± 9 years, and 23 (85.2%) were male. Intraocular pressure increased after the water-drinking test in both pre-laser peripheral iridotomy (17.0 vs. 19.3 mmHg, P < .001) and post-laser peripheral iridotomy (15.6 vs. 18.6 mmHg, P < .001) conditions. The thickness values of central cornea increased slightly after the water-drinking test in pre-laser peripheral iridotomy (535 vs. 538 μm, P = .001) compared with post-laser peripheral iridotomy (532 vs. 536 μm, P = .003). The water-drinking test had no significant effect on other biometric or anterior chamber parameters, before or after laser peripheral iridotomy.

CONCLUSIONS

The water-drinking test increased intraocular pressure, both before and after laser peripheral iridotomy. Laser peripheral iridotomy had no significant effect on the amount of intraocular pressure change after the water-drinking test. The water-drinking test has no effect on other biometric or anterior chamber parameters.

Intraocular pressure fluctuation after water drinking test in primary angle-closure glaucoma and primary open-angle glaucoma

Context:

Only a few studies have assessed intraocular pressure (IOP) changes during the water drinking test (WDT) in patients with primary angle-closure glaucoma (PACG).

Aims:

The aim of this study is to investigate IOP changes during WDT in patients with PACG versus primary open-angle glaucoma (POAG).

Settings and Design:

This was a prospective and single tertiary center study.

Materials and Methods:

PACG and POAG patients (n = 15 each) without prior glaucoma surgery were enrolled and subjected to WDT, wherein they consumed an amount of water proportional to their body weight within 10 min. IOP was measured at baseline and every 15 min for 1 h after water intake.

Statistical Analysis Used:

Intergroup comparisons were performed using Mann–Whitney U-test for continuous variables and Chi-square test for categorical variables. Wilcoxon signed-ranks test was used for comparisons of IOP before and after water intake in the two groups. Regression analysis was used to determine factors associated with IOP fluctuations during WDT.

Results:

IOP changes over 1 h after water intake showed no significant differences between groups. The mean maximum fluctuation from baseline was 3.61 ± 2.49 and 3.79 ± 1.91 mmHg, respectively, in the PACG and POAG groups. The mean peak IOP was 19.17 ± 4.32 and 19.87 ± 3.44 mmHg in the PACG and PAOG groups, respectively. The axial length and anterior chamber depth showed no correlations with IOP fluctuations.

Conclusions:

We found similar IOP fluctuation curves and peak IOP values in both PACG and POAG patients subjected to WDT. These findings suggest that WDT is a useful test to induce IOP peaks in both POAG and PACG patients.

Selective Laser Trabeculoplasty Reduces Intraocular Pressure Peak in Response to the Water Drinking Test

PURPOSE

To determine the effect of selective laser trabeculoplasty (SLT) on intraocular pressure (IOP) peak and fluctuation induced by the water drinking test (WDT) in patients with open-angle glaucoma and ocular hypertension.

METHODS

Patients with open-angle glaucoma or ocular hypertension underwent the WDT before and after SLT within a 12-month period. No other changes to therapeutic regimen were permitted. IOP was measured with a Goldmann applanation tonometer at baseline and every 15 minutes for 45 minutes following a fluid challenge of 800 mL over 15 minutes. Baseline, peak, and percentage fluctuation in IOP from baseline were compared using a repeated measures analysis of variance with Bonferroni adjustment.

RESULTS

Twenty eyes from 20 patients were included in this study. The median patient age was 73±15 years (interquartile range) and 70% of patients were female. Ten eyes (50%) had a diagnosis of primary open-angle glaucoma and 10 eyes had ocular hypertension. Following SLT there was a statistically significant reduction in mean baseline IOP from 16.9±2.4 to 14.2±2.3 mm Hg (P<0.001), peak IOP from 21.9±3.7 to 16.9±3.1 mm Hg (P<0.001).

CONCLUSIONS

Patients with open-angle glaucoma and ocular hypertension treated with SLT have significantly reduced peak IOPs and fluctuation in IOP in response to the WDT.