Time of Peak Intraocular Pressure during Water Drinking Test and Modified Phasing Among Glaucoma Patients in South-East Nigeria

Abstract

Background: High intraocular pressure (IOP) peaks and fluctuations which are among the significant risk factors for glaucoma development and progression can be detected through water drinking test (WDT) and phasing. Aim: To determine the time of peak IOP during WDT and modified phasing among primary open angle glaucoma (POAG) patients on medical treatment at Enugu State University of Science and Technology Teaching Hospital Parklane (ESUTTHP), Enugu. Methodology: The study was a hospital based cross sectional study on POAG patients on medical treatment attending the eye clinic of ESUTTHP, Enugu. One hundred and thirty patients were selected by simple random sampling. Their eyes were examined which included visual acuity assessment, follow-up clinic intraocular pressure measurement, gonioscopy, anterior and posterior segments examination. WDT and modified phasing were carried out on them. WDT was done over 2 hours after intake of 1 liter of water with intraocular pressure measured every 15 minutes. Modified phasing was done over 8 hours with intraocular pressure measured at 2 hourly intervals. Data analysis was done using SPSS version 20 (U.S.A). Results: A total of 130 POAG patients (260 eyes) on medical treatment were examined comprising of 56 males (43.1%) and 74 females (56.9%). Their age ranged between 42 and 83 years with mean age of 62.25 ± 9.002. The peak IOP occurred in 90.2% of patients within the first 1 hour of water drinking test with 23.6% of the eyes having peak IOP at 15 minutes, 24.0% at 30 minutes, 22.9% at 45 minutes, 20.2% of eyes at 60 minutes, 6.6% of eyes at 75 minutes, 2.3% at 90 minutes, 0.0% at 105 minutes and 0.4% at 120 minutes. The peak IOP occurred in two-thirds (74.1%) of eyes within the first 4 hours of commencing modified phasing while 25.8% had their IOP peak after 4 hours with 30.6% of the eyes having peak IOP at onset of the test, 28.2% at 2 hours, 15.3% at 4 hours, 16.1% at 6 hours and 9.7% at 8 hours. Conclusion: WDT may be done over 1 hour instead of 2 hours as a quick clinic test to detect IOP peaks among glaucoma patients on treatment. Some POAG patients also have IOP peaks occurring in the afternoon during modified phasing and such peaks should not be missed in those patient’s management.