To evaluate the short- and long-term variability of intraocular pressure (IOP) in eyes with primary open-angle glaucoma (POAG).
Twenty-two patients who had previously been implanted with a sulcus based IOP sensor (EyeMate, Implandata GmbH, Germany) were included. They were requested to obtain at least 4 IOP measurements per day. Data were grouped according to the eye and the medication, so that an eye treated with a particular medication was considered as one group, and the same eye treated with a different medication during the observation period was considered as a different group. A day was divided in 7 periods: ‘Night’ Midnight to 5:59am, ‘early’ 6am to 7:59am, ‘morning’ 8am to 10:59am, ‘noon’ 11am to 1:59pm, ‘afternoon’ 2pm to 5:59pm, ‘evening’ 6pm to 8:59, ‘late’ 9pm to 11:59pm. Short-term variability at a particular period was defined as the variability in IOP measurements obtained during that period on different days within 3 months of each other. Long-term variability was defined as the variability in IOP measurements obtained during a particular period on different days over a time period of ≥ 1 year. Variability was assessed using intraclass correlation coefficients (ICCs).
The mean age of study participants was 67.8 ± 6.8 years and 36.4 % were female. The mean follow-up duration of patients was 19.2 ± 21.3 months (median 9, range: 1-58). Overall, 92,860 IOP measurements over 15,811 measurement days were obtained and analyzed during the study period. The number of measurements obtained from each eye ranged from one per day to 277 per day. ICCs for short-term variability among the seven periods during the day ranged from 0.52 (morning) to 0.66 (early). Long-term ICCs ranged from 0.29 (night) to 0.51 (late).
Continual IOP monitoring shows that IOP has moderate short-term and high long-term variability in glaucoma patients. These findings demonstrate that single IOP measurements do not characterize day to day variations in IOP. Moreover, they show the importance of continual IOP monitoring in glaucoma patients.

Copyright © 2020. Published by Elsevier Inc.