Reproducibility of the water drinking test

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.

Intraocular Peak Pressure in Patients under Treatment with Fixed Combination of Bimatoprost/ Timolol/ Brimonidine once Daily versus Twice Daily

PRECIS

We investigate the efficacy of triple-fixed-combination of Bimatoprost/Brimonidine/Timolol once and twice a day, demonstrating higher intraocular pressure reduction with once-a-day use, and discuss possible implications based on previous literature.

PURPOSE

To compare the efficacy of fixed combination bimatoprost-timolol-brimonidine (Triplenex ®) instilled once-daily with twice-daily in primary open-angle glaucoma.

PATIENTS AND METHODS

Randomized clinical trial at a public eye care institution. Thirty patients with primary open-angle glaucoma were followed-up for three-months. The right and left eyes of these patients were randomly assigned to once-daily, (10:00 PM) or twice-daily, (10:00 AM; 10:00 PM) regimens of fixed combination bimatoprost-timolol-brimonidine. Intraocular pressure peaks were obtained with the water drinking test before the introduction of this medication (basal WDT0), one month (WDT 1), 2 months (WDT2) and 3 months (WDT3) after starting the use of the fixed combination of Bimatoprost/ Timolol/ Brimonidine (Triplenex®). Variation from peak intraocular pressure at WDT3 to peak at WDT0 was compared within groups of two versus once daily regimen.

RESULTS

Sixty eyes of 30 patients (age 70.67±9.70▒y) were included in this study. Baseline clinical characteristics were comparable between groups. Mean reduction in peak intraocular pressure from WDT0 to WDT3 was 6.1±6.1▒mmHg (30.5%) in the eyes receiving one drop per day and 4.3 ±5.7▒mmHg (21.5%) in the eyes receiving two drops per day (P=0.023). Mean reduction in peak intraocular pressure considering all WDT was also higher in the group with once-a-day treatment (5.90±6.03▒mmHg vs. 4.46±4.28▒mmHg, P=0.006).

CONCLUSION

Fixed combination of bimatoprost 0.01%, brimonidine tartrate 0.15% and timolol maleate 0.5% once-a-day is more effective in reducing peak intraocular pressure as measured by the WDT than twice-a-day dosing.

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.

Correlation and Agreement Between Water Drinking Test and Modified Diurnal Tension Curve in Untreated Glaucoma Patients in Nigeria

PURPOSE

To determine the correlation and agreement between intraocular pressure (IOP) parameters evaluated by the modified diurnal tension curve (mDTC) and the water drinking test (WDT) in primary open-angle glaucoma (POAG) in an indigenous African population.

MATERIALS AND METHODS

This was a prospective, interventional, comparative study of 50 newly diagnosed, previously untreated primary open-angle glaucoma patients at the out-patient clinic of the Eleta Eye Institute, Ibadan. A series of IOP measurements were taken 2 hourly (from 7:00 AM to 3:00 PM) for the mDTC, using Goldmann applanation tonometer. The WDT was performed thereafter. The patients drank 800 mL of water within 5 minutes, and another series of IOP measurements were taken every 15 minutes for a duration of 1 hour from the moment water was fully ingested. Both the mDTC and the WDT were performed on the same day. IOP peak, mean, and IOP fluctuations were estimated from the data collected. Comparison between the mDTC and the WDT was performed using the paired Student T test for means, Pearson correlation analysis for correlation, and Bland-Altman analysis for agreement.

RESULTS

Estimated IOP parameters were significantly higher for the WDT than for the mDTC. The average peak IOP was 27.8±4.0 mm Hg during the WDT and 24.9±3.1 mm Hg during the mDTC (P<0.001). The average mean IOP was 25.8±3.6 mm Hg during the WDT and 22.3±2.4 mm Hg during the mDTC (P<0.001). The average IOP fluctuation was higher (6.6±2.9 mm Hg) during the WDT compared with 4.7±2.0 mm Hg during the mDTC. The mean and peak IOPs were strongly correlated between the mDTC (r=0.729, P<0.001) and the WDT (r=0.658, P<0.001). IOP fluctuation, however, showed weak correlation between the mDTC and the WDT (r=0.258, P=0.709).

CONCLUSIONS

There is a strong positive correlation between IOP parameters (peak and mean IOP) estimated from the WDT and the mDTC. The peak and mean IOP can be estimated from the WDT, which is quicker, compared with the mDTC. This is more relevant in low resource settings with limited personnel, time, and resource constraints. In addition, higher IOP values were obtained from the WDT compared with the mDTC, and therefore could serve as a useful practical way to determine target peak in order to optimize IOP control in glaucoma patients.

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.

Water Drinking Test: Intraocular Pressure Changes after Tube Surgery and Trabeculectomy

PURPOSE

To study the effects of filtration surgeries (tube and trabeculectomy) on changes in intraocular pressure after a water-drinking test.

METHODS

In this prospective, non-randomized, comparative clinical study, 30 patients who had tube surgery and 30 age- and sex-matched trabeculectomy patients underwent a water-drinking test. Only one eye of each patient was included. The baseline intraocular pressure was ≤21 mmHg in all enrolled eyes with or without adjunctive topical medications. After the water-drinking test, the intraocular pressure was measured and recorded at 15, 30, 45, and 60 minutes and the results were compared between the two groups.

RESULTS

In both groups, intraocular pressure significantly increased from baseline at all measured time-points (P < 0.001). In the trabeculectomy group, the average intraocular pressure increased from 14.8 ± 2.9 to 18.8 ± 4.7 mmHg at 30 minutes, but decreased at 60 min (18.0 ± 5.2 mmHg). In the Tube group, intraocular pressure increased incrementally until the last measurement (14.2 ± 3.9, 18.8 ± 5.6, and 19.7 ± 6.0 mmHg at baseline, 30, and 60 minutes, respectively). The end-pressure difference (intraocular pressure at 60 minutes vs. baseline) was significantly greater in the tube group (5.6 ± 3.6 mmHg; 41% change) than in the trabeculectomy group (3.2 ± 4.7; 23% change; P = 0.03).

CONCLUSION

Intraocular pressure significantly increased after the water-drinking test in both the groups. Intraocular pressure started to decline 30 minutes after the water-drinking test in the trabeculectomy group, while it continued to increase up to 60 minutes in the Tube group. This finding may have implications regarding the efficacy or safety of the procedures in advanced glaucoma patients.