Predictive Value of the Water Drinking Test and the Risk of Glaucomatous Visual Field Progression

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.

The Effect of Combined Phacoemulsification and Endo-Cyclophotocoagulation on Intraocular Pressure Fluctuation Assessed by the Water Drinking Test in Patients with Primary Open Angle Glaucoma

INTRODUCTION

The aim of this study was to assess the effect of phacoemulsification and endo-cyclophotocoagulation (phaco-ECP) on intraocular pressure (IOP) fluctuation as assessed by the water drinking test (WDT) in primary open angle glaucoma (POAG).

METHODS

This was a prospective observational study carried out at a tertiary referral centre. POAG patients on topical antiglaucoma medications and planned for phaco-ECP were recruited. WDT was performed before surgery and 6 weeks postoperatively by drinking 10 mL/kg of water in 5 min followed by serial IOP by Goldmann applanation tonometry measurements at 15, 30, 45, and 60 min. Mean IOP, IOP fluctuation (difference between highest and lowest IOP), IOP reduction, and factors affecting IOP fluctuation were analysed.

RESULTS

Twenty eyes from 17 patients were included. Baseline IOP was similar before (14.7 ± 2.7 mm Hg) and after (14.8 ± 3.4 mm Hg, p = 0.90) surgery. There was no difference in mean IOP (17.6 ± 3.4 mm Hg vs. 19.3 ± 4.7 mm Hg pre- and postoperative, respectively, p = 0.26) or peak IOP (19.37 ± 3.74 mm Hg vs. 21.23 ± 5.29 mm Hg, p = 0.25), albeit a significant reduction in IOP-lowering medications (2.2 ± 1.15 vs. 0.35 ± 0.93, p < 0.001) postoperatively. IOP fluctuation was significantly greater (6.4 ± 3.2 mm Hg vs. 4.6 ± 2.1 mm Hg, p = 0.015) with more eyes having significant IOP fluctuation of ≥6 mm Hg (11 eyes [55%] vs. 4 eyes [20%], p < 0.001) postoperatively. Factors that were significantly associated with increased postoperative IOP fluctuations were higher preoperative IOP fluctuation (β = 0.69, 95% CI 0.379-1.582, p = 0.004) and more number of postoperative antiglaucoma medications (β = 0.627, 95% CI 0.614-3.322, p = 0.008).

CONCLUSION

Reducing aqueous production with phaco-ECP does not eliminate IOP fluctuation in POAG patients. The increase in postoperative IOP fluctuation suggests increased outflow resistance after phaco-ECP.

The Effect of the Water Drinking Test on Ocular Parameters and Choroidal Thickness in Glaucoma Suspects

Background and objectives: We aimed to evaluate the effects of the water drinking test (WDT) on several systemic and ocular parameters, including choroidal thickness, which was assessed through optical coherence tomography angiography (OCTA), in glaucoma suspects. Materials and Methods: A total of 40 eyes from 20 glaucoma suspects without any systemic or ocular diseases were included in this prospective observational study. All the participants undertook the WDT, which required the drinking of 1 L of table water in 5 min. The outcome measures included IOP, systolic and diastolic blood pressure (SBP and DBP), mean arterial pressure (MAP), mean ocular perfusion pressure (MOPP), ocular pulse amplitude (OPA), and subfoveal and peripapillary choroidal thickness, which were assessed at baseline and at four 15 min intervals after the WDT. Generalized least squares models and mixed model analyses that take into account repeated measurements were used to assess the changes over time of these parameters. Results: All the ocular and systemic parameters showed statistically significant changes at all time points compared to baseline apart from choroidal thickness. The peak changes were an IOP of 20.1 mmHg versus 17.3 mmHg at 45 min, an SBP of 137.6 mmHg versus 125 mmHg at 30 min, a DBP of 95.9 mmHg versus 85.7 mmHg at 15 min, and an MOP of 53.51 mmHg versus 48.89 mmHg at 15 min. Conclusions: Despite elevations in IOP and significant changes in all the assessed systemic parameters, the WDT was not associated with changes in choroidal thickness in glaucoma suspects.

Elevated IOP following a bladder filling protocol: A case report

Purpose

We describe a patient with elevated intraocular pressure (IOP) secondary to an oral water bolus and examine the utility of the water-drinking test.

Observations

A 66-year-old male with a history of hypertension presented with headache, bilateral retro-orbital ache, and blurry vision. Symptoms began shortly after his radiation treatment for prostate cancer, for which he consumed a water bolus to fill his bladder 30 minutes prior to treatment initiation. On exam, he had bilateral elevated IOP that responded to topical IOP-lowering medications. Gonioscopy demonstrated open angles and fundus exam showed non-glaucomatous optic nerves with pronounced retinal venous tortuosity. The water-drinking test showed a peak intraocular pressure of 20 mmHg in the right eye (5 mmHg increase from baseline) and 23 mmHg in the left eye (8 mmHg increase from baseline), suggesting impairment of the outflow system in the left compared to the right eye. He was started on topical IOP-lowering therapy and followed in our clinic as a glaucoma suspect.

Conclusions

Consumption of a water bolus can be associated with IOP elevation and may be a risk factor in patients with otherwise normal IOPs at risk for glaucoma. The water-drinking test was historically used as provocative testing for open-angle glaucoma and may have an updated role in evaluating at-risk patients without ocular hypertension.

Duration of the hypotensive effect of prostaglandin analogues measured with the water drinking test in glaucoma patients

OBJECTIVE

To measure the magnitude and duration of the hypotensive effect of two prostaglandin analogues in glaucoma patients using the water drinking test (WDT).

METHODS

Patients received latanoprost or travoprost every 24 h and then every 48 h. Untreated WDT were performed at 7 am and with treatment 12, 36 and 44 h after the last dose; intraocular pressure (IOP) peak, fluctuation and the difference between peak and isolated IOP measurements at consultation times were calculated.

RESULTS

Forty-one eyes of 21 patients with primary open-angle glaucoma were included; 22 eyes received latanoprost, and 19 received travoprost. Mean untreated isolated IOP was 17.20 standard deviation (S.D.) 3.73 and 16.95 S.D. 2.61 mmHg and peak pressure 22.45 S.D. 2.91 and 21.58 S.D. 3.79 mmHg, for the latanoprost and travoprost groups, respectively. With treatment, peak pressure was reduced by 22.64% and 20.29% at 12 h, 18.44% and 14.64% at 36 h and 16.17% and 14.46% at 44 h, respectively. The fluctuation without treatment was 4.36 and 5.11 mmHg, and with treatment at 12 h was reduced to 2.77 and 2.89 mmHg, increasing again at 36 and 44 h.

CONCLUSIONS

A hypotensive effect was evident up to 44 h after the last dose of latanoprost and travoprost, similar for the two drugs and decreasing over time. IOP fluctuation was only reduced at 12 h.

Peak Intraocular Pressure Time during Water Drinking Test and Its Relationship with Glaucoma Severity

Purpose

To investigate the association between the time of occurrence of intraocular pressure (IOP) peaks during the water-drinking test (WDT) and visual field damage in a cohort of primary open-angle glaucoma (POAG) patients.

Methods

In this retrospective, cross-sectional study, 98 eyes from 49 consecutive POAG patients were followed in a referral clinical practice. The relationship between the time when IOP peaks occurred during the WDT and the visual field mean deviation (MD) assessed with 24-2 visual field was tested with mixed-effects models.

Results

MD value was significantly associated with the time of IOP peak occurrence (P = 0.020) when adjusting for the number of medications, but not with the IOP peak values (P = 0.238).

Conclusion

The time of IOP peaks occurrence during the WDT was associated with glaucoma severity among treated POAG patients.

Comparison of intraocular pressure peak and fluctuations among Filipino patients with non-glaucomatous eyes and glaucoma suspects using water drinking test and diurnal intraocular pressure

AIM

To compare the intraocular pressure (IOP) peaks and fluctuations using water drinking tests (WDTs) and mean diurnal IOP among Filipino patients with normal eyes and glaucoma suspects.

METHODS

This prospective study included normal and glaucoma suspect patients. Each patient underwent both WDT and mean diurnal examination on separate visits. For mean diurnal examination, IOP was recorded every 2h for 8h while in WDT, IOP was recorded prior to WDT, and post-WDT at 5, 15, 30, 45, and 60min. IOP peak was recorded as the highest IOP for both methods, and IOP fluctuation was recorded as highest IOP minus lowest IOP.

RESULTS

With the comparison of diagnostic tests, both normal eyes and glaucoma suspect groups, the peak IOP was caught at 15min. Comparative analysis of both groups also showed that the peak IOP measurements were statistically higher for the WDT compared to mean diurnal IOP (P=0.039, P=0.048 under normal group and P=0.032 and P=0.031 under glaucoma suspect group). Similarly, the WDT had a statistically higher mean IOP fluctuation score than the mean diurnal IOP method in both groups (P=0.003, P=0.011 under normal group; P=0.002 and P=0.005 under glaucoma suspect group).

CONCLUSION

This study shows that WDT is a comparable diagnostic exam in predicting IOP fluctuations than mean diurnal measurement. WDT is a promising diagnostic procedure for risk assessment in glaucoma.

Comparison of intraocular pressure variability detected by day diurnal variation to that evoked by water drinking

Purpose

To determine correlation and agreement between intraocular pressure (IOP) peak and fluctuations detected by day diurnal variation (day DVT) to that after the water-drinking test (WDT).

Methods

Patients (18-80 years) with glaucoma, suspects, and ocular hypertension (OHT) were enrolled. IOP readings were taken on applanation tonometer, at 2-h intervals, from 8 AM to 3 PM (DVT). 3 PM IOP served as WDT baseline. Patients consumed water (10 mL/kg) in 5-15 min, at 3 PM, after they fluid fasted for 2 h. IOP was recorded every 15 min, from 3.30 to 4.30 PM.

Results

A total of 200 eyes (100 patients) were included. 58.5% were established glaucoma, 32% suspects, 9.5% OHT. Correlation between mean and peak IOP by WDT and day DVT was strong and significant (r = 0.89, P < 0.00; r = 0.73, P < 0.00) while it was weak for fluctuation (r = 0.12, P < 0.07). Agreement on Bland and Altman plots was limited for mean IOP and poor for peak and fluctuations.

Conclusion

An exaggerated WDT response may indicate a compromised outflow facility and warrant close patient monitoring but the WDT cannot substitute day DVT in our clinical practice.

Comparison between provocative test-based and long-term intraocular pressure parameters in patients with stable open-angle glaucoma

PURPOSE

To compare provocative test-based and long-term intraocular pressure variation parameters in patients with stable open-angle glaucoma.

METHODS

A prospective observational study was carried out in which stable open-angle glaucoma patients (⩾3 years of follow-up without any changes on current medical regimen) were consecutively enrolled. All patients were submitted to a water-drinking test. Long-term intraocular pressure parameters were obtained from isolated intraocular pressure measurements from each visit (⩾5 visits). We investigated the correlation and agreement between the following water-drinking test and long-term intraocular pressure parameters: mean, peak, and fluctuation. In addition, the percentage of eyes with significant intraocular pressure peaks during the water-drinking test (defined as a difference ⩾25% between water-drinking test intraocular pressure peak and mean long-term intraocular pressure) was assessed.

RESULTS

Sixty-three eyes from 63 open-angle glaucoma patients (mean age, 60.7 ± 11.8 years) were included. Mean and water-drinking test intraocular pressure peak correlated significantly with mean (r = 0.67) and maximum long-term intraocular pressure (r = 0.52), respectively (p < 0.01). The correlation between water-drinking test intraocular pressure fluctuation and long-term intraocular pressure fluctuation was not significant (p = 0.45). Limits of agreement from Bland-Altman plots exceeded the maximum allowed difference between methods (3 mm Hg) for all the intraocular pressure parameters analyzed, suggesting poor agreement between water-drinking test-derived and long-term intraocular pressure values. Overall, significant water-drinking test intraocular pressure peaks were observed in 39.7% of these eyes with stable open-angle glaucoma.

CONCLUSION

Although some water-drinking test-based and long-term intraocular pressure parameters correlate significantly, water-drinking test results may not reflect the long-term intraocular pressure profile of stable open-angle glaucoma patients, as their agreement is poor. Many of these patients may experience significant water-drinking test intraocular pressure peaks, despite long-standing stable disease and unchanged medical regimen.

Neurovascular Changes Associated With the Water Drinking Test

PURPOSE

The water drinking test (WDT) is currently used to temporarily elevate intraocular pressure (IOP) and predict peak IOP in glaucoma. This study investigates neurovascular changes associated with WDT in normal subjects.

METHODS

The effect of WDT (1 L in 5 min) on IOP, mean brachial blood pressure, heart rate, and pattern electroretinogram was assessed within the next hour in 16 healthy subjects (mean age: 33.5±7.9 y). As a control, testing was repeated in the same subjects without WDT 1 week later.

RESULTS

Compared with control, WDT resulted in significant peak changes of the following parameters compared with baseline: IOP: +1.7±1.8 mm Hg after 30', mean brachial blood pressure: +3.9±6.3 mm Hg after 15'; heart rate: -9.2±9.8 bpm after 15', pattern electroretinogram latency: +2.1±0.9 ms after 15'.

CONCLUSIONS

In addition to IOP elevation, WDT was associated with significant changes of hemodynamic parameters and retinal ganglion cell function in young healthy subjects. As these represent risk factors for glaucoma, their assessment upon WDT might increase its predictive power for glaucoma development.

Exogenous influences on intraocular pressure

Intraocular pressure (IOP), the pressure within the eyeball, is a function mainly of the production and elimination of aqueous humour. Balanced IOP helps to maintain the eyeball contour, allowing proper refraction of light in the anterior segment of the eye. Increases in IOP can cause injury to the ocular structure, typically the optic nerve head and retinal ganglion cells. IOP increase, additionally, is a risk factor for glaucoma progression. However, it is not unusual that glaucoma worsens despite well-managed IOP; indeed, glaucoma can develop and progress even within the normal IOP range. IOP measured once during daytime office hours might not provide sufficient information for effective glaucoma management. In fact, IOP is not a fixed value but rather changes over time: it fluctuates with the intrinsic circadian rhythm and can also change in various lifestyle-related situations (eg, with body posture, during exercise, while holding breath and according to dietary habits). It is therefore worth exploring the various factors that can affect IOP and glaucoma risk. In this review, the various exogenous influences on IOP in the literature are investigated.

Role of the water-drinking test in medically treated primary open angle glaucoma patients

PURPOSE

The water-drinking test (WDT) has recently re-emerged as a possible way to determine the competency of the trabecular meshwork. We performed a prospective interventional study to test the hypothesis that the WDT could be useful in assessing fluctuations in patients undergoing treatment for primary open angle glaucoma (POAG).

METHODS

We included 122 patients; 62 on medical treatment for POAG (n=123 eyes) and 60 controls (n=120 eyes). The study group had been on intraocular pressures (IOP) lowering treatment continuously for at least 3months with stable IOP. The WDT was performed during fasting and was considered positive if it fluctuated ≥6mmHg.

RESULTS

The patients on medical treatment had a mean age of 50.56±18.45 years vs. 51.35±11.22 for the controls (P=0.34); with 71% being female in the study group and 77% in the control group. In the study group; 52% were on beta blockers (n=64), 27% combination of two or more medications (n=33), 19% prostaglandin analogues (n=24) and 2% alpha agonists (n=2). The WDT was positive in 17.07% (n=21) in the study group and 2.5% (n=3) in the control group (P=0.0001). The mean fluctuation was 7.14±2.15mmHg in the study group and 6.00±0mmHg in the controls (P=0.33). A positive WDT was found in 33.33% (n=11) of those on combination therapy; 12.5% (n=3) prostaglandin analogues and 10.94% (n=7) beta blockers (P=0.03). Combination therapy had the highest positive WDT fluctuation (7.54±2.87) followed by prostaglandin analogues (7.00±1.00) and beta blockers (6.57±0.78) with a P value of 0.44.

CONCLUSIONS

The WDT can identify significant fluctuations in eyes with POAG that are medically treated.