The relation between intraocular pressure peak in the water drinking test and visual field progression in glaucoma

Sector-specific Association of Intraocular Pressure Dynamics in Dark-room Prone Testing and Visual Field Defect Progression in Glaucoma

PURPOSE

To investigate sectoral differences in the relationship between intraocular pressure (IOP) dynamics during dark-room prone testing (DRPT) and visual field (VF) defect progression in primary open-angle glaucoma (POAG) patients.

DESIGN

Retrospective, longitudinal study.

PARTICIPANTS

This retrospective study included 116 eyes of 84 POAG patients who underwent DRPT and had at least 5 reliable VF tests conducted over a more than 2-year follow-up period. We excluded eyes with mean deviation worse than -20 dB or a history of intraocular surgery or laser treatment.

METHODS

Average total deviation (TD) was calculated in the superior, central, and inferior sectors of the Humphrey 24-2 or 30-2 program. During DRPT, IOP was measured in the sitting position, and after 60 minutes in the prone position in a dark room, IOP was measured again. The relationship between IOP change during DRPT, IOP after DRPT, and TD slope in each quadrant was analyzed with a linear mixed-effects model, adjusting for other potential confounding factors.

MAIN OUTCOME MEASURES

Total deviation slope in each quadrant, IOP change during DRPT, and IOP after DRPT.

RESULTS

Intraocular pressure after DRPT and IOP change during DRPT were 18.16 ± 3.42 mmHg and 4.92 ± 3.12 mmHg, respectively. Superior TD slope was significantly associated with both IOP after DRPT (β = -0.28, P = 0.003) and IOP change during DRPT (β = -0.21, P = 0.029), while central (β = -0.05, P = 0.595; β = -0.05; P = 0.622) and inferior (β = 0.05, P = 0.611; β = 0.01, P = 0.938) TD slopes were not.

CONCLUSION

Dark-room prone testing might be a useful test to predict the risk of superior VF defect progression in eyes with POAG.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

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 association between intraocular pressure dynamics during dark-room prone testing and intraocular pressure over a relatively long-term follow-up period in primary open-glaucoma patients

PURPOSE

To investigate the relationship between the dynamics of intraocular pressure (IOP) during dark-room prone testing (DRPT) and IOP over a relatively long-term follow-up period.

METHODS

This retrospective study enrolled 84 eyes of 51 primary open-angle glaucoma patients who underwent DRPT for whom at least three IOP measurements made using Goldmann applanation tonometry were available over a maximum follow-up period of two years. We excluded eyes with a history of intraocular surgery or laser treatment and those with changes in topical anti-glaucoma medication during the follow-up period. In DRPT, IOP was measured in the sitting position, and after 60 min in the prone position in a dark room, IOP was measured again. In this study, IOP fluctuation refers to the standard deviation (SD) of IOP, and IOP max indicates the maximum value of IOP during the follow-up. The relationship between these parameters was analyzed with a linear mixed-effects model, adjusting for clinical parameters including age, gender, and axial length.

RESULTS

IOP increased after DRPT with a mean of 6.13 ± 3.55 mmHg. IOP max was significantly associated with IOP after DRPT (β = 0.38; p < 0.001). IOP fluctuation was significantly associated with IOP change in DRPT (β = 0.29; p = 0.007).

CONCLUSION

Our findings suggest that short-term and relatively long-term IOP dynamics are associated. Long-term IOP dynamics can be predicted by DRPT to some extent.

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.

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.

Short-Time Changes of Intraocular Pressure and Biomechanics of the Anterior Segment of the Eye during Water Drinking Test in Patients with XEN GelStent

Purpose: Little is known about short-term changes in intraocular pressure (IOP) following minimally invasive glaucoma surgeries, such as post-XEN GelStent implantation. Although the importance of corneal biomechanics in glaucoma diagnostics has been reported, little work has been conducted on postoperative description of changes when the structure of the anterior segment is altered. The aim of presented study was to evaluate the changes in the biomechanical parameters of the anterior segment of the post-XEN GelStent implantation eyes. Patients and Methods: This investigator-initiated, open-label, prospective, single-center study recruited patients. Patients with primary open-angle glaucoma (POAG) after XEN GelStent implantation versus matched POAG controls (considered as control group/CG) treated pharmacologically were screened. Water loading was conducted using 10 mL of water per kilogram of body weight for ≤5 min. Goldmann applanation tonometry (GAT), corneal hysteresis (CH), and corneal resistance factor (CRF) were performed before water loading and after every 15 min up to 1 h. Results: The water drinking test (WDT) was positive in 3.7% (1 out of 27) of patients in the post-XEN group compared with 22.7% (5 out of 22) of patients in the control group (CG; p < 0.05). Mean fluctuations in GAT during the WDT were higher in the CG group (3.6 ± 2.5 mmHg vs. 2.9 ± 1.3 mmHg, p < 0.001). CRF and CH changed significantly only in the post-XEN group. The mean peak of CH and CRF occurred at 15 and 30 min of the test in the post-XEN group (p = 0.001). Conclusion: WDT is important to assess the ability of compensation mechanisms to reduce fluctuations in IOP after water upload. The relationship between biomechanics of the anterior segment and glaucoma may have substantial impact on surgical outcome evaluation.

Efficacy and safety of timolol-dorzolamide fixed-combination three times a day versus two times a day in newly diagnosed open-angle glaucoma

Objective

This study aimed to compare the therapeutic efficacy and safety of dorzolamide/timolol fixed-combination(Cosopt) in newly diagnosed primary open-angle glaucoma (POAG) patients.

Methods

In this prospective, interventional case series, newly POAG patients were included. Patients were started on Cosopt twice a day (BID) for one month and then switched to three times a day (TDS) for an additional month. Patients underwent comprehensive ophthalmic examination, diurnal intraocular pressure (IOP), blood pressure (BP), and 24-h heart rate (HR) measurements at baseline, month 1(BID), and month 2(TDS). Throughout the study, all adverse events were monitored by the investigators.

Results

In 31 POAG patients that completed the study, the mean baseline IOP was 23.1 ± 3.15 mmHg. IOP was decreased significantly 16.5 ± 2.21 at one month (p < .0001) and 13.9 ± 2.23 mmHg at 1 and 2 months follow up (p < .0001). IOP was significantly lower in month 2 compared to month 1 (p = .0004). While Cosopt BID significantly reduced the mean 24-h systolic BP and mean 24-h HR from baseline (p < .0001), the mean 24-h systolic BP and HR remained unchanged with Cosopt TDS compared to BID (p = .62).

Conclusions

Cosopt TDS has a superior IOP-lowering effect than Cosopt BID in POAG patients with comparable safety profiles.

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.

Correlation between intraocular pressure obtained with water drinking test versus modified diurnal tension curve measurement in pseudoexfoliation glaucoma

PURPOSE

The aim of this paper was to study the correlation and agreement between the intraocular pressure (IOP) peak value and fluctuations detected with the modified diurnal tension curve (mDTC) and the water drinking test (WDT) in pseudoexfoliation glaucoma (XFG) patients.

METHODS

This prospective observational study enrolled 42 eyes of 42 XFG patients. The IOPs were measured at 2-h intervals from 8 am to 4 pm with a Goldmann applanation tonometer by a single observer to establish the mDTC. The WDT was then performed between 4 and 5 pm on the same day and the IOP was measured 4 times at 15-min intervals after water ingestion. The IOP_peak, IOP_mean, IO _min, and IOP_fluctuation were measured with both the mDTC and WDT. The paired sample t test, Spearman's correlation coefficient and Bland-Altman plots were used for statistical analysis.

RESULTS

The mean age of the 42 patients consisting of 24 females and 18 males was 66.9 ± 6.8 years, and the mean central corneal thickness was 517.7 ± 29.1 µm. The mean values with the mDTC and WDT measurements were 15.05 ± 2.75 mmHg and 17.17 ± 3.25 mmHg (p ≤ 0.0001, r = 0.884) for IOP_mean, 16.76 ± 3.45 mmHg and 18.92 ± 3.94 mmHg (p ≤ 0.0001, r=0.787) for IOP_peak, and 13.61 ± 2.56 mmHg and 15.11 ± 2.84 mmHg (p ≤ 0.0001, r=0.824) for IOP_min, respectively, and a positive correlation was present between these values.

CONCLUSION

There was a positive correlation between the peak, minimum, and mean IOP values determined using the mDTC and WDT in treated XFG patients. WDT can be used as an alternative in the assessment of the IOP in these patients as a more practical method.

Intraocular pressure and corneal biomechanical changes after water-drinking test in glaucoma patients

Purpose:

To evaluate intraocular pressure (IOP) and corneal biomechanical changes after water-drinking test (WDT) in glaucomatous and normal eyes using Ocular Response Analyzer (ORA).

Methods:

This prospective study included 30 medically controlled, 30 surgically treated glaucoma patients and 30 normal individuals. Baseline measurements included central corneal thickness (CCT), ORA-derived corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg). Measurements were repeated 15, 30, and 60 min after drinking 1000 mL of water. Changes in ORA parameters were compared among the groups.

Results:

All groups showed a significant increase in IOPg and IOPcc at all test points. Peak IOP occurred at 15 min and decreased gradually over time but did not reach the baseline values at 60 min. The surgery group had significantly lower baseline IOPg and IOPcc (10.7 ± 3.1 and 12.8 ± 3.7 mmHg, P = 0.001 and 0.01), lower peak IOPg and IOPcc (14.4 ± 4.6 and 16.2 ± 4.6 mmHg, P = 0.003 and 0.034), and lower percent IOPg and IOPcc fluctuations (13 ± 5.6 and 15 ± 5.9, P = 0.0001 and 0.002), respectively, compared to the medical group. Baseline CH and its fluctuations were not significantly different among the groups. CH decreased to a trough corresponding to peak IOPcc. There was a significant negative correlation between IOPcc and CH (r = −0.609, P < 0.001). The medical group showed more CRF fluctuations compared to normal group.(P = 0.039).

Conclusion:

Surgically treated glaucomatous eyes show less IOP fluctuations and lower peak IOP after WDT compared to medically controlled and normal eyes.

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.

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

PURPOSE

The purpose of this is to test the hypothesis the intraocular pressure (IOP) peaks during a stress test [the water drinking test (WDT)] can estimate the risk of future visual field progression in treated primary open-angle glaucoma (POAG) patients.

PATIENTS AND METHODS

Design: Prospective, longitudinal study.

SETTING

Clinical practice.

STUDY POPULATION

Treated POAG patients whose IOP was ≤18 mm Hg and who had no IOP-lowering interventions between the date of the WDT and the last eligible visual field.

INTERVENTION

At baseline examination, patients underwent the WDT and were then followed at regular intervals with office-based IOP measurements and visual field testing.

MAIN OUTCOME MEASURE

Cox-proportional hazards survival analysis testing the predictive value of IOP peaks during the WDT versus IOP measurements during office hours on visual field progression.

RESULTS

A total of 144 eyes of 96 patients with baseline visual field damage ranging from mild to severe followed for a mean of 28 months were analyzed. In the multivariable analysis adjusting for potential confounders, higher IOP peaks during the WDT were predictive of future visual field progression (hazard ratio=1.11; 95% confidence interval, 1.02 to 1.21; P=0.013). The average and peak IOP during office hours over the same follow-up period were not significantly associated with progression (P=0.651 and 0.569, respectively).

CONCLUSIONS

IOP peaks detected with the WDT were predictive of future visual field progression in a treated POAG population. This stress test could be a useful tool for risk assessment in daily practice.

Effects of water drinking test on ocular blood flow waveform parameters: A laser speckle flowgraphy study

The water-drinking test (WDT) is a provocative test used in glaucoma research to assess the effects of elevated intraocular pressure (IOP). Defective autoregulation due to changes in perfusion pressure may play a role in the pathophysiology of several ocular diseases. This study aims to examine the effects of WDT on ocular blood flow (in the form of pulse waveform parameters obtained using laser speckle flowgraphy) to gain insight into the physiology of ocular blood flow and its autoregulation in healthy individuals. Changes in pulse waveform parameters of mean blur rate (MBR) in the entire optic nerve head (ONH), the vasculature of the ONH, the tissue area of the ONH, and the avascular tissue area located outside of the ONH were monitored over time. Significant increases in the falling rate of MBR over the entire ONH and its tissue area and decreases in blowout time (BOT) of the tissue area were observed only at 10 minutes after water intake. Significant increases in the skew of the waveform and the falling rate were observed in the vasculature of the ONH at 40 and 50 minutes after water intake, respectively. In the avascular region of the choroid, the average MBR increased significantly up to 30 minutes after water intake. Furthermore, the rising rate in this region increased significantly at 20 and 40 minutes, and the falling rate and acceleration-time index were both significantly increased at 40 minutes after water intake. Our results indicate the presence of effective autoregulation of blood flow at the ONH after WDT. However, in the choroidal region, outside of the ONH, effective autoregulation was not observed until 30 minutes after water intake in healthy study participants. These pulse waveform parameters could potentially be used in the diagnosis and/or monitoring of patients with glaucoma.

The Water-Drinking Test Revisited: An Analysis of Test Results in Subjects with Glaucoma

PURPOSE

The Water-Drinking Test (WDT) has been shown to predict the diurnal IOP change. This study evaluates the factors that may affect the WDT results.

METHODS

This study was conducted on 203 glaucoma patients who had undergone trabeculectomy (53) or tube surgery (31), or had a medically controlled open-angle (82) or closed-angle (37) glaucoma. IOP was measured at baseline and then every 15 minutes over a one-hour period after drinking water. The main outcome measures were IOP change (increase in IOP from baseline) at all measurement time points, IOP peak (highest IOP after drinking water), IOP fluctuation (difference between IOP peak and baseline), and assessing the association of these IOPs with a patient's demographic and management modalities.

RESULTS

The mean age of the participants was 54±18 years, and 113 (56%) were male. Female patients showed greater IOP fluctuation than males (7.28 vs. 5.92 mm Hg; P=0.016), and a greater IOP peak (22.7 vs. 20.1 mm Hg; P=0.001). The observed associations between gender and IOP changes were only significant in <50 years. IOP at 60 minutes was greater in tube than trabeculectomy (5.6 vs. 3.1 mm Hg; P=0.007). The number of topical medications showed a direct independent association with IOP changes (P<0.001). Compared to other classes of topical medications, latanoprost showed lower WDT-IOP profile (P=0.0003).

CONCLUSIONS

WDT-IOP change was diminished in subjects on latanoprost, and was greater in females <50 years, and those on greater number of medications.

Applications of the water drinking test in glaucoma management

Intraocular pressure (IOP) peaks and means have been considered important factors for glaucoma onset and progression. However, peak IOP detection depends only on appropriated IOP checks at office visits, whereas the mean IOP requires longitudinal IOP data collection and may be affected by the interval between visits. Also, IOP peak assessment is necessary to verify if the peak pressure of a given patient is in target range, to evaluate glaucoma suspect risk, the efficacy of hypotensive drugs and to detect early loss of IOP control. The water-drinking test has gained significant attention in recent years as an important tool to evaluate IOP peaks and instability. The main objective of this review was to present new findings and to discuss the applicability of the water-drinking test in glaucoma management.

Intraocular pressure dynamics with prostaglandin analogs: a clinical application of the water-drinking test

AIM

To evaluate the clinical applicability of the water-drinking test in treatment-naive primary open-angle glaucoma patients.

METHODS

Twenty newly diagnosed primary open-angle glaucoma patients and 20 healthy controls were enrolled in this prospective study. The water-drinking test was performed at baseline and 6 weeks and 3 months after prostaglandin analog treatment. Peak and fluctuation of intraocular pressure (IOP) measurements obtained with the water-drinking test during follow-up were analyzed. Analysis of variance for repeated measures and paired and unpaired t-tests were used for statistical analysis.

RESULTS

The mean baseline IOP values in patients with primary open-angle glaucoma were 25.1±4.6 mmHg before prostaglandin analog treatment, 19.8±3.7 mmHg at week 6, and 17.9±2.2 mmHg at month 3 after treatment. The difference in mean baseline IOP of the water-drinking tests was statistically significant (P<0.001). At 6 weeks of prostaglandin analog treatment, two patients had high peak and fluctuation of IOP measurements despite a reduction in baseline IOP. After modifying treatment, patients had lower peak and fluctuation of IOP values at month 3 of the study.

CONCLUSION

Peak and fluctuation of IOP in response to the water-drinking test were lower with prostaglandin analogs compared with before medication. The water-drinking test can represent an additional benefit in the management of glaucoma patients, especially by detecting higher peak and fluctuation of IOP values despite a reduced mean IOP. Therefore, it could be helpful as a supplementary method in monitoring IOP in the clinical practice.

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.

Intraocular Pressure Characteristics of Exfoliative Glaucoma and Exfoliation Syndrome as Determined With the Water Drinking Test

PURPOSE

To investigate the intraocular pressure (IOP) characteristics of patients with exfoliation glaucoma (XFG) and exfoliation syndrome (XFS) during the water drinking test (WDT).

METHODS

This was a prospective observational study undertaken at an academic setting. Consecutive patients with XFG whose office IOP levels were <21 mm Hg, normotensive XFS patients, and control subjects underwent WDT, which involved ingestion of 1 L of water within 5 minutes. The IOP was measured before and 4 times after water ingestion at 15-minute intervals. Maximum IOP (IOPmax), mean IOP (IOPmean), IOP increase (IOPΔ) from baseline IOP to IOPmax, and percentage of IOP fluctuation (IOPfluct) during the WDT were compared across groups. One-way analysis of variance (ANOVA) test or the Kruskal-Wallis test was used for comparisons.

RESULTS

The age, gender ratios, visual acuity level, central corneal thickness, and office IOP levels were similar between the 3 groups. As compared with patients with XFS and controls, XFG patients revealed significantly higher values for all IOP measurements at 15 minutes intervals as well as IOPmax (25.1±4.0 mm Hg, 18.7±2.8 mm Hg, 18.6±2.5mm Hg; P<0.001), IOPmean (22.6±3.3mm Hg, 17.2±2.6 mm Hg, 17.2±2.4 mm Hg; P<0.001), IOPΔ (9.2±3.4 mm Hg, 4.4±2.1 mm Hg, 3.7±1.5 mm Hg; P<0.001), and IOPfluct (60.1±24.0%, 33.4±20.0%, 25.7±11.3%; P<0.001).

CONCLUSIONS

Medically treated XFG patients, but not XFS subjects, reveal significant IOP elevations during WDT indicative of impaired trabecular outflow facility.

Endothelial nitric oxide synthase deficiency influences normal cell cycle progression and apoptosis in trabecular meshwork cells

AIM

To clarify how the endothelial nitric oxide synthase (eNOS, NOS3) make effect on outflow facility through the trabecular meshwork (TM).

METHODS

Inhibition of NOS3 gene expression in human TM cells were conducted by three siRNAs. Then the mRNA and protein levels of NOS3 in siRNA-treated and negative control (NC) cells were determined, still were the collagen, type IV, alpha 1 (COL4A1) and fibronectin 1 by real-time PCR and Western blot analysis. In addition, NOS3 concentrations in culture supernatant fluids of TM cells were measured. Cell cycle and cell apoptosis analysis were performed using flow cytometry.

RESULTS

The mRNA level of NOS3 was decreased by three different siRNA interference, similar results were obtained not only of the relative levels of NOS3 protein, but also the expression levels of COL4A1 and fibronectin 1. The number of cells in S phase was decreased, while contrary result was obtained in G2 phase. The number of apoptotic cells in siRNA-treated groups were significant increased compared to the NC samples.

CONCLUSION

Abnormal NOS3 expression can make effects on the proteins levels of extracellular matrix component (e.g. fibronectin 1 and COL4A1). Reduced NOS3 restrains the TM cell cycle progression at the G2/M-phase transition and induced cell apoptosis.

Intraocular pressure and glaucoma: Is physical exercise beneficial or a risk?

Intraocular pressure may become elevated with muscle exertion, changes in body position and increased respiratory volumes, especially when Valsalva manoeuver mechanisms are involved. All of these factors may be present during physical exercise, especially if hydration levels are increased. This review examines the evidence for intraocular pressure changes during and after physical exercise. Intraocular pressure elevation may result in a reduction in ocular perfusion pressure with the associated possibility of mechanical and/or ischaemic damage to the optic nerve head. A key consideration is the possibility that, rather than being beneficial for patients who are susceptible to glaucomatous pathology, any intraocular pressure elevation could be detrimental. Lower intraocular pressure after exercise may result from its elevation causing accelerated aqueous outflow during exercise. Also examined is the possibility that people who have lower frailty are more likely to exercise as well as less likely to have or develop glaucoma. Consequently, lower prevalence of glaucoma would be expected among people who exercise. The evidence base for this topic is deficient and would be greatly improved by the availability of tonometry assessment during dynamic exercise, more studies which control for hydration levels, and methods for assessing the potential general health benefits of exercise against any possibility of exacerbated glaucomatous pathology for individual patients who are susceptible to such changes.

Reproducibility of the water drinking test

OBJECTIVES

To investigate the reproducibility of the water drinking test in determining intraocular pressure peaks and fluctuation. It has been suggested that there is limited agreement between the water drinking test and diurnal tension curve. This may be because it has only been compared with a 10-hour modified diurnal tension curve, missing 70% of IOP peaks that occurred during night.

METHODS

This was a prospective, analytical and comparative study that assesses the correlation, agreement, sensitivity and specificity of the water drinking test.

RESULTS

The correlation between the water drinking test and diurnal tension curve was significant and strong (r=0.93, Confidence interval 95% between 0.79 and 0.96, p<01). A moderate agreement was observed between these measurements (pc=0.93, Confidence interval 95% between 0.87 and 0.95, p<.01). The agreement was within±2mmHg in 89% of the tests.

DISCUSSION

Our study found a moderate agreement between the water drinking test and diurnal tension curve, in contrast with the poor agreement found in other studies, possibly due to the absence of nocturnal IOP peaks.

CONCLUSIONS

These findings suggest that the water drinking test could be used to determine IOP peaks, as well as for determining baseline IOP.

Ibopamine challenge testing differentiates glaucoma suspect, stable glaucoma and progressive glaucoma cases

BACKGROUND

An ibopamine challenge is a novel technique for assessing glaucoma using ibopamine, a topical drug which temporarily increases aqueous production. We aimed to determine whether change in intraocular pressure (IOP) and/or optic cup volume (OCV) during the test differentiated between glaucoma patients at different stages of disease; namely, glaucoma suspects (GS), glaucoma patients who are stable (SG) and glaucoma patients who have demonstrated rapid progression (PG).

DESIGN

Non-randomized clinical trial evaluating a diagnostic test.

PARTICIPANTS

Sixty-one patients were recruited through glaucoma clinics at the Flinders Medical Centre (24 GS, 24 SG and 13 PG).

METHODS

Patients underwent IOP measurement and OCV assessment using optical coherence tomography. Two drops of ibopamine 2% solution were instilled into the study eye of each patient. After 45 min, IOP and OCV were reassessed. Changes from baseline were compared between groups.

MAIN OUTCOME MEASURE

Change in IOP and OCV after ibopamine challenge.

RESULTS

Following the ibopamine challenge, IOP increased by 1.8 mmHg for GS patients, 4.5 mmHg for SG patients (P = 0.003) and 8.1 mmHg for PG patients (P < 0.0001). OCV increased by 0.2% for GS patients, 0.6% for SG patients and 5.5% for PG patients. This was not significantly different between GS patients and SG patients; however, it was significantly different between GS patients and PG patients (P < 0.0001), and between SG and PG patients (P = 0.001).

CONCLUSION

GS patients may be differentiated from those with SG or PG by their IOP response, and SG may be differentiated from PG patients by their change in OCV following an ibopamine challenge.

Reproducibility of the water drinking test in treated glaucomatous patients

BACKGROUND

To evaluate the reproducibility of intraocular pressure peaks and fluctuation elicited during the water drinking test in treated glaucomatous patients with a long follow-up interval.

DESIGN

Retrospective cohort study in a tertiary care practice.

PARTICIPANTS

Thirty-four treated primary open-angle glaucoma patients.

METHODS

All patients underwent the water drinking test performed in two consecutive visits without any change in the therapeutic regimen. The mean interval between tests was 4.85 (range: 3-6) months. Reproducibility of peak and fluctuation during the water drinking test was assessed using intraclass correlation coefficients. Bland-Altman analysis was used to assess the agreement of intraocular pressure peaks and fluctuation measured between two consecutive tests.

MAIN OUTCOME MEASURES

Intraclass correlation and agreement of intraocular pressure peaks and fluctuation between visits.

RESULTS

There were no significant differences in baseline intraocular pressure values (mean ± standard deviation, 11.73 ± 2.36 and 11.61 ± 2.71 mmHg; P = 0.72) and peaks (14.55 ± 3.41 and 15.02 ± 3.66 mmHg, respectively; P = 0.163) detected during the water drinking test between the first and second visits. There was also no significant difference between the average intraocular pressure fluctuation values (2.82 ± 1.99 and 3.41 ± 2.54 mmHg, respectively; P = 0.135). Intraocular pressure peaks and fluctuation presented intraclass correlation coefficients of 0.85 (P < 0.001) and 0.50 (P < 0.001), respectively.

CONCLUSIONS

Our results demonstrate excellent reproducibility of intraocular pressure peaks during the water drinking test. Intraocular pressure fluctuation did not reveal good reproducibility, though. These results emphasize the applicability of this test to assess treatment efficacy in daily practice and interventional studies.

Correlation between biomechanical responses of posterior sclera and IOP elevations during micro intraocular volume change

PURPOSE

This study tested the hypothesis that intraocular pressure (IOP) elevations, induced by controlled increase of intraocular volume, are correlated with the biomechanical responses of the posterior sclera.

METHODS

Porcine globes were tested within 48 hours postmortem. The first group of globes (n = 11) was infused with 15 μL of phosphate-buffered saline at three different rates to investigate rate-dependent IOP elevations. The second group (n = 16) was first infused at the fast rate and then underwent inflation tests to investigate the relationship between IOP elevations (ΔIOP) and scleral strains. The strains in the superotemporal region of the posterior sclera were measured by ultrasound speckle tracking. Linear regression was used to examine the association between ΔIOP due to micro-volumetric infusion and the scleral strains at a specific inflation pressure.

RESULTS

The average ΔIOP was 14.9 ± 4.3 mm Hg for the infusion of 15 μL in 1 second. The ΔIOP was greater for the faster infusion rates but highly correlated across different rates (P < 0.001). A significant negative association was found between the ΔIOP and the tangential strains in both the circumferential (R(2) = 0.54, P = 0.003) and meridian (R(2) = 0.53, P = 0.002) directions in the posterior sclera.

CONCLUSIONS

This study showed a substantial increase in IOP, with a large intersubject variance during micro-volumetric change. A stiffer response of the sclera was associated with larger IOP spikes, providing experimental evidence linking corneoscleral biomechanics to IOP fluctuation. In vivo measurement of corneoscleral biomechanics may help better predict the dynamic profile of IOP.

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.

Current understanding of conventional outflow dysfunction in glaucoma

PURPOSE OF REVIEW

Regulation of intraocular pressure by the conventional (trabecular) outflow pathway is complicated, involving a myriad of mechanical and chemical signals. In most, intraocular pressure is maintained within a tight range over a lifetime. Unfortunately in some, dysfunction results in ocular hypertension and open-angle glaucoma. In the context of established knowledge, this review summarizes recent investigations of conventional outflow function, with the goal of identifying areas for future inquiry and therapeutic targeting.

RECENT FINDINGS

Mechanical stimulation of conventional outflow cells due to intraocular pressure fluctuations impacts contractility, gene expression, pore formation, enzyme activity, and signaling. Numerous local signaling mediators in the conventional pathway such as bioactive lipids, cytokines, nitric oxide, and nucleotides participate in the regulation of outflow. Interestingly outflow through the conventional pathway is not uniform, but segmental, with passageways constantly changing due to focal protease activity of trabecular cells clearing extracellular matrix materials. The relationship between extracellular matrix expression and trabecular meshwork contractility appears to coordinately impact outflow resistance and is the target of a new class of drugs, the Rho kinase inhibitors.

SUMMARY

The conventional outflow pathway is a dynamic, pressure-sensitive tissue that is vulnerable to pathology on many fronts, each representing a therapeutic opportunity.

Finite element modeling of the viscoelastic responses of the eye during microvolumetric changes

A linear viscoelastic finite element model was built to investigate factors that influenced the intraocular pressure (IOP) elevations due to micro-volumetric changes in the eye at three different rates. The viscoelastic properties of the cornea and the sclera, including the instantaneous modulus, equilibrium modulus, and relaxation time constants, parametrically varied to examine their effects on IOP elevations at different rates of volumetric changes. The simulated responses were in good agreement with the previously reported experimental results obtained from porcine globes, showing the general trend of higher IOP elevations at faster rates. The simulations showed that all viscoelastic properties influenced the profile of the dynamic IOP due to volumetric changes, and the relative significance of a specific parameter was highly dependent on the rate of change.

Correlation between Peak Intraocular Pressure of the Water Drinking Test and Peak Intraocular Pressure Induced by Intravenous Methylprednisolone Pulse Therapy

<b><i>Purpose:</i></b> It was the aim of this study to determine any possible correlation between the peaks and changes in intraocular pressure (IOP) of a water drinking test and intravenous methylprednisolone pulse therapy (IVMPT) IOP response. <b><i>Methods:</i></b> Patients with rheumatic disorders scheduled for IVMPT with normal ocular examination received a WDT before and after 3 days of IVMPT. The maximum value of IOPs detected during the WDT or IVMPT was regarded as peak IOP, and IOP change was defined as the difference between peak IOP and baseline IOP. <b><i>Results:</i></b> The mean ± standard deviation (SD) IOPs on the first (21.9 ± 4.6 mm Hg; p = 0.04), second (21.9 ± 4.1 mm Hg; p = 0.03) and third (21.3 ± 4.2 mm Hg; p = 0.01) days of 20 enrolled patients were greater than that at baseline (19.3 ± 2.8 mm Hg). The mean ± SD of peak IVMPT IOP response was 23.9 ± 3.7 mm Hg, and IVMPT IOP change was 4.6 ± 3.7 mm Hg. These values for the first and second WDTs were 22.9 ± 4.9 and 3.9 ± 4.07 as well as 24.1 ± 4.6 and 3.00 ± 2.9 mm Hg, respectively. A significant correlation was observed between the first WDT and IVMPT IOP changes (r = 0.5, p = 0.007) and peak IOPs (r = 0.6, p = 0.001). <b><i>Conclusion:</i></b> WDT, a low-cost and feasible test in clinical practice, may be a useful tool in determining the IOP peak and change following IVMPT.

Reproducibility of intraocular pressure peak and fluctuation of the water-drinking test

BACKGROUND

The water-drinking test has been used as a stress test to evaluate the drainage system of the eye. However, in order to be clinically applicable,a test must provide reproducible results with consistent measurements. This study was performed to verify the reproducibility of intraocular pressure peaks and fluctuation detected during the water-drinking test in patients with ocular hypertension and open-angle glaucoma.

DESIGN

A prospective analysis of patients in a tertiary care unit for glaucoma treatment.

PARTICIPANTS

Twenty-four ocular hypertension and 64 open-angle glaucoma patients not under treatment.

METHODS

The water-drinking test was performed in 2 consecutive days by the same examiners in patients not under treatment. Reproducibility was assessed using the intraclass correlation coefficient.

MAIN OUTCOME MEASURES

Peak and fluctuation of intraocular pressure obtained with the water-drinking test were analysed for reproducibility.

RESULTS

Eighty-eight eyes from 24 ocular hypertension and 64 open-angle glaucoma patients not under treatment were evaluated. Test and retest intraocular pressure peak values were 28.38 ± 4.64 and 28.38 ± 4.56 mmHg, respectively (P = 1.00). Test and retest intraocular pressure fluctuation values were 5.75 ± 3.9 and 4.99 ± 2.7 mmHg, respectively (P = 0.06). Based on intraclass coefficient, reproducibility was excellent for peak intraocular pressure (intraclass correlation coefficient = 0.79) and fair for intraocular pressure fluctuation (intraclass correlation coefficient = 0.37).

CONCLUSION

Intraocular pressure peaks detected during the water-drinking test presented excellent reproducibility, whereas the reproducibility of fluctuation was considered fair.

Diurnal tension curves for assessing the development or progression of glaucoma: an evidence-based analysis

CLINICAL NEED

CONDITION AND TARGET POPULATION There are two main types of glaucoma, primary open angle (POAG) and angle closure glaucoma, of which POAG is the more common type. POAG is diagnosed by assessing degenerative changes in the optic disc and loss of visual field (VF). Risk factors for glaucoma include an increase in intraocular pressure (IOP), a family history of glaucoma, older age and being of African descent. The prevalence of POAG ranges from 1.1% to 3.0% in Western populations and from 4.2% to 8.8% in populations of African descent. Usually the IOP associated with POAG is elevated above the normal distribution (10-20 mmHg), but when IOP is not elevated it is often referred to as normal-tension glaucoma (NTG). In population based studies, approximately one-third to half of the patients with glaucomatous VF loss have normal IOP on initial examination. People with elevated IOP (>21 mmHg), but with no evidence of optic disc or VF damage have ocular hypertension. It has been estimated that 3 to 6 million people in the United States including 4% to 7% of those older than 40 years have elevated IOP without detectable glaucomatous damage on standard clinical tests. An Italian study found the overall prevalence of ocular hypertension, POAG, and NTG in 4,297 people over 40 years of age to be 2.1%, 1.4% and 0.6% respectively.

DIURNAL CURVES FOR INTRAOCULAR PRESSURE MEASUREMENT

DIURNAL CURVE: In normal individuals, IOP fluctuates 2 to 6 mmHg over a 24 hour period. IOP is influenced by body position with higher readings found in the supine relative to the upright position. As most individuals sleep in the supine position and are upright during the day, IOP is higher on average in people, both with and without glaucoma, in the nocturnal period. IOP is generally higher in the morning compared to the afternoon. Multiple IOP measurements over the course of a day can be used to generate a diurnal curve and may have clinical importance in terms of diagnosis and management of patients with IOP related conditions since a solitary reading in the office may not reveal the peak IOP and fluctuation that a patient experiences. Furthermore, because of diurnal and nocturnal variation in IOP, 24-hour monitoring may reveal higher peaks and wider fluctuations than those found during office-hours and may better determine risk of glaucoma progression than single or office-hour diurnal curve measurements. There is discrepancy in the literature regarding which parameter of IOP measurement (e.g., mean IOP or fluctuation/range of IOP) is most important as an independent risk factor for progression or development of glaucoma. The potential for increased rates or likelihood of worsening glaucoma among those with larger IOP swings within defined time periods has received increasing attention in the literature. According to an expert consultant: The role of a diurnal tension curves is to assess IOP in relationship to either a risk factor for the development or progression of glaucoma or achievement of a target pressure which may direct a therapeutic change.Candidates for a diurnal curve are usually limited to glaucoma suspects (based on optic disc changes or less commonly visual field changes) to assess the risk for development of glaucoma or in patients with progressive glaucoma despite normal single office IOP measurements.Clinically diurnal tension curves are used to determine the peak IOP and range.

SINGLE IOP MEASUREMENTS

Intraocular pressure fluctuation as a risk factor for progression of glaucoma has also been examined without the use of diurnal curves. In these cases, single IOP measurements were made every 3-6 months over several months/years. The standard deviation (SD) of the mean IOP was used as a surrogate for fluctuation since no diurnal tension curves were obtained.

OBJECTIVE

To determine whether the use of a diurnal tension curve (multiple IOP measurements over a minimum 8 hour duration) is more effective than not using a diurnal tension curve (single IOP measurements) to assess IOP fluctuation as a risk factor for the development or progression of glaucoma.To determine whether the use of a diurnal tension curve is beneficial for glaucoma suspects or patients with progressive glaucoma despite normal single office IOP measurements and leads to a more effective disease management strategy.

RESEARCH METHODS

LITERATURE SEARCH

SEARCH STRATEGY

A literature search was performed on July 22, 2010 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 2006 until July 14, 2010. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with unknown eligibility were reviewed with a second clinical epidemiologist, then a group of epidemiologists until consensus was established. The quality of evidence was assessed as high, moderate, low or very low according to GRADE methodology.

INCLUSION CRITERIA

Open angle glaucoma (established or OHT high risk) in an adult populationIOP measurement by Goldmann applanation tonometry (the gold standard)Number and timing of IOP measurements explicitly reported (e.g., 5 measurements a day for 5 visits to generate a diurnal curve or 1 measurement a day [no diurnal curve] every 3 months for 2 years)IOP parameters include fluctuation (range [peak minus trough] or standard deviation) and meanOutcome measure = progression or development of glaucomaStudy reports results for ≥ 20 eyesMost recent publication if there are multiple publications based on the same study

EXCLUSION CRITERIA

Angle closure glaucoma or pediatric glaucomaCase reportsIOP measured by a technique other than GAT (the gold standard)Number and timing of IOP measurements not explicitly reported

OUTCOMES OF INTEREST

Progression or development of glaucoma

CONCLUSION

There is very low quality evidence (retrospective studies, patients on different treatments) for the use of a diurnal tension curve or single measurements to assess short or long-term IOP fluctuation or mean as a risk factor for the development or progression of glaucoma. There is very low quality evidence (expert opinion) whether the use of a diurnal tension curve is beneficial for glaucoma suspects or patients with progressive glaucoma, despite normal single office IOP measurements, and leads to a more effective disease management strategy.

[Risk factors of glaucoma progression: intraocular pressure fluctuations]

Intraocular pressure is not a fixed value and varies both over short-term periods and periods of several months or years. In healthy subjects, the circadian fluctuations in intraocular pressure are moderate, generally not exceeding 5 mmHg. In patients with glaucoma or ocular hypertension, intraocular pressure fluctuations are greater and circadian rhythms may be inverted. These fluctuations are probably involved in the conversion of ocular hypertension to glaucoma or glaucoma progression. Large observational clinical studies, however, are not unanimous on the role played by intraocular pressure fluctuations on the risk of conversion from ocular hypertension to glaucoma or glaucoma worsening. Nevertheless, it is important for each patient to estimate the short-term and long-term fluctuations and to prioritize a treatment that minimizes these fluctuations.