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.

Water-drinking Test in Normal Tension Glaucoma Patients with and without High Myopia

This prospective study aims to evaluate the correlation between myopic severity and normal tension glaucoma (NTG) by investigating IOP changes following water-drinking test (WDT). We reviewed 61 patients with NTG during an interval of three years, of which 31 were highly myopic (HM) and 30 were non-highly myopic (NHM). Basic characteristics such as age, gender, spherical equivalence, baseline IOP, visual field parameters, and average retinal nerve fiber layer thickness were compared between NTG patients with and without high myopia. The IOP parameters obtained following WDT were then compared between the HM and NHM NTG groups. Intragroup analysis revealed significant IOP elevation following WDT within the 45-minute duration in both groups. However, no significant differences in IOP parameters were observed between the HM and NHM NTG groups. In conclusion, although the pattern of IOP fluctuations was different, the extent of IOP fluctuations and peak IOP following WDT was similar between the HM and NHM NTG groups, suggesting that myopic severity probably has a limited role in NTG. Lastly, WDT was an effective tool for eliciting IOP peaks when 24-hour IOP monitoring is not available.

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.

Evaluation of daily changes of Intraocular pressure in glaucomatous patients with modified diurnal tension curve versus water drinking test

Background Glaucoma is a chronic optic neuropathy characterized by the excavation of the optic disc due to atrophy of the retinal ganglion cells. A progression of such atrophy leads to reduction of the visual field and eventually to the loss of sight at the end-stage of the disease, Glaucoma is the second leading cause of blindness worldwide Objectives To study the correlation between intraocular pressure (IOP) fluctuation during water drinking test (WDT) and the IOP fluctuation of modified diurnal tension curve (mDTC) in glaucomatous eyes Patients and Methods Fifty participants (24 males and 26 females) were recruited in this prospective study; forty participants with known Primary Open Angle Glaucoma and the other ten participants with non- glaucomatous healthy eyes which served as control. Patients attending the outpatient clinic at Al-Demerdash Hospital and Cairo Fatemic Hospital from October 2018 to March 2019 were prospectively recruited. Four IOP measurements were taken at 8:00 am, 12:00 pm, 4:00 pm and 8:00 pm which represented the mDTC, while WDT was represented by a single measurement of IOP before ingestion of one liter of water over five minutes, followed by three IOP measurements after ingestion of this amount of water at thirty minute intervals. Results Distribution of the studied participants as regards Age and sex: 50 participants were included in the this study. 40 presented the case group (20 males and 20 females) and the mean age of the case group was 54.7 years, 10 presented the control group(4 males and 6 females) and the mean age of the control group was 51.2years. 59% of participants had a peak IOP at 8:00 am, while 10% had a peak IOP at 12:00 pm, 6% at 4:00 pm and 25% of the participants had IOP peak at 8:00 pm during the mDTC. In the WDT, 96% of the participants had a peak IOP after 30 minutes of ingesting one liter of water, while 4% had a peak IOP after 60 minutes. None of the participants had IOP peak after 90 minutes of ingesting one liter of water.. The IOP fluctuations detected during the WDT were significantly correlated to fluctuations observed during the mDTC. Conclusion The data of this study suggested that WDT can be used as a useful provocative test for the detection of the diurnal IOP peaks and fluctuation observed in the glaucoma patients.

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 [ Dbox]). 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.

A COMPARATIVE STUDY RELATING WATER DRINKING TEST AND INTRA OCULAR PRESSURE IN DIFFERENT AGE GROUPS

AIM:To determine the behavior of IOP in different age groups among normal populations after water drinking test for a period of time. MATERIALS AND METHODS:This is a prospective study involving normal healthy individual taken from different age groups 20-50 years,with no relevant past medical and surgical history. Patients were instructed to drink 1Litre of water over a period of 5-10minutes after 8 hours of overnight fasting and the IOP was checked before drinking water and every 15minutes for 1 hour period followed by 2 hours after drinking water using schiotz tonometer.The difference in baseline IOP and IOP at 1 hour and 2 hour was evaluated among different age groups . RESULT: 100 patients from the age groups 20-50 years were studied .The mean baseline IOP was in the range of 12.4mmHg and the mean IOP after 1 hour was 15.3mmHg.A difference of 4-4.5 mmHg were noted in the age group of 40- 50 years .The IOP was gradually decreasing to 12.78mmHg over a period of 2 hours after WDT. CONCLUSION: The higher age group the more the rise in the IOP after WDT which concludes that as the age increases drinking litres of water over a few minutes will substantially increase the IOP,which might damage the optic nerve.