Comparative evaluation of modified diurnal tension curve with water drinking test among glaucoma suspects at University of Port Harcourt Teaching Hospital, Rivers State, Nigeria

Objective: The objective of the study was to assess the correlation of intraocular pressure (IOP) peaks and fluctuation obtained using a modified diurnal tension curve (mDTC) and water drinking test (WDT) and to investigate the relevance of routine use of WDT in glaucoma suspects at University of Port Harcourt Teaching Hospital, Port Harcourt, Rivers State Nigeria. Materials and Methods: Glaucoma suspects were enrolled in this prospective comparative study. A total of 138 participants were recruited. All participants were subjected to two hourly IOP checks for 8 h (mDTC starting from 8:00 am). The WDT was done the following day, starting at 8:00 am. There was a 2-h water fast before the commencement of the WDT and IOP was measured every 15 min for 1 h after ingestion of 1 L of water. Results: Out of the 138 glaucoma suspects recruited for the study, 57 were male and 81 females, with a mean age of 37.8 ± 11.7 years. The mean peak IOP measured during mDTC (19.0 ± 3.5 mmHg) was statistically different from that measured during WDT (20.9 ± 4.4 mmHg; P < 0.001). The mean IOP fluctuation measured during the mDTC (5.6 ± 1.9 mmHg) was also statistically different from that measured by WDT (6.9 ± 2.7 mmHg) ( P < 0.001). The peak IOP measured during mDTC showed a strong correlation with peak IOP during WDT ( r = 0.840); however, there was moderate agreement between the two peaks ( k = 0.408). The IOP peaks of mDTC and WDT showed excellent strength of association (Cronbach’s alpha = 0.901) and poor strength of association for the fluctuation in IOP (Cronbach’s alpha = 0.556). Conclusion: The WDT can provide an easier, nonexpensive, and less time-consuming method of peak IOP determination, which will aid in the timely management of glaucoma patients.