Abstract
Purpose: :
To study the intraocular pressure and ocular pulse amplitude profile of the Dynamic Contour Tonometer during the Water Drinking Test.
Methods: :
Primary open angle glaucomatous (POAG) patients were recruited from the Glaucoma Center of the University of Sao Paulo School of Medicine during the period of 1 month. Glaucoma was defined by the presence of optic neuropathy with associated visual field (VF) defect, demonstrated in at least 2 consecutive reliable examinations using Humphrey Standard Automated Perimetry (Humphrey Inc., Dublin, CA, USA). All patients were under topical treatment in both eyes during the study. The WDT was performed as follows:(1) water deprivation for at least 4 hours before the test, (2) followed by the ingestion of 1 (one) liter of tap water in 5 minutes, (2) and IOP measurements 15, 30 and 45 minutes thereafter using Dynamic Contour Tonometry. The DCT provides a score (Q) representing the quality of the IOP measurement. The score ranges from 1 (optimum) to 5 (unacceptable). For the present study, only measurements with Q scores of 1 or 2 were considered for analysis. Comparison between means was performed using paired student t-test, assuming statistical significance for a p value < 5%. The reproducibility of measurements was analyzed using the Intraclass Correlation Coefficient (ICC).
Results: :
Forty POAG eyes were included. Patients’ average age was 54.6 years; 66% were females and 80% Caucasians. Average corneal central thickness (CCT) was 534.2 µm (range 523.5 - 586.2). The ICC was strong for IOP and OPA measurements using DCT. The mean IOP was 15.34 ± 3.09 mmHg and 18.09 ±3.24 mmHg before and after the test, respectively (p<0.001). During the WDT, IOP peaks occurred more frequently at 30 minutes from baseline using DCT (46.1%). The mean OPA increased from a baseline value of 1.93 ± 0.68 mmHg to 2.72 ± 0.77 mmHg (p<0.001), mostly 15 minutes before the IOP peak.
Conclusions: :
During the Water Drinking Test there is an increase in the Ocular Pulse Amplitude followed by a transient intraocular pressure rise using DCT.
Keywords: intraocular pressure • outflow: trabecular meshwork • trabecular meshwork