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

Joanna Przeździecka-Dołyk,Agnieszka Jóźwik,Marta Misiuk-Hojło,Iwona Helemejko,Ewa Wałek,Magdalena Asejczyk-Widlicka

doi:10.3390/jcm11010175

Abstract

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.

Highlights

The water drinking test (WDT) was first described as a provocation test for glaucoma in the 1960s
The WDT can be performed with a fixed volume of water upload or it can be adjusted for each person as 10 mL/kg body weight [1,2,3,4,5]
According to the review published by Susanna et al (2017), an intraocular pressure (IOP) peak in WDT that exceeds 5 mmHg is associated with six times increased risk of new onset of glaucoma

Summary

Introduction

The water drinking test (WDT) was first described as a provocation test for glaucoma in the 1960s. It is a type of stress test which helps to assess the changes in eye pressure that may happen during the day. According to the review published by Susanna et al (2017), an IOP peak in WDT that exceeds 5 mmHg is associated with six times increased risk of new onset of glaucoma. In the study reported by Poon et al [4], WDT was considered as positive if IOP peak exceeded. The WDT is experiencing renewed interest as the test that can indicate the impact of short-term changes in IOP after glaucoma surgeries 6 mmHg, whereas Susanna et al (2005) found that a significant difference of 1.9 mmHg in IOP peaks between the eyes that showed visual field progression and those that did not show any progress [2].

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Conclusion