Purpose
To evaluate the 24-hour circadian intraocular pressure (IOP) fluctuation profile before and after laser peripheral iridotomy (LPI) in newly diagnosed subjects with primary angle closure (PAC) using a contact lens based IOP sensor.
Methods
Seven newly diagnosed primary angle closure subjects from a glaucoma clinic underwent diurnal IOP profiling with Goldmann applanation tonometry (GAT at 8 am, 10 am, 12 noon and 2 pm), gonioscopy and 24-hour IOP profiling using a contact lens based IOP sensor (Sensimed TriggerfishTM, Lausanne, Switzerland) before and after LPI. Mean GAT IOP and GAT IOP fluctuation (Maximum IOP - Minimum IOP) were compared using Wilcoxon rank sum test. Serial measurement analysis of the time-weighted average of 24-hour IOP fluctuation (in arbitrary units) and comparison between specific times of the day were performed using non-parametric methods.
Results
The mean age of study participants was 65 (±5.6) years and most of the subjects were of Chinese origin (6/7) and female (5/7). Mean baseline GAT IOP was 23.29 (±0.49) mm Hg. The angle remained closed in 3/7 (42.9%) subjects even after LPI. Comparing pre and post LPI, there was no difference in mean diurnal GAT IOP [19.66 (±2.09) vs 16.7 (±3.57) mm Hg, p=0.25], or mean GAT IOP fluctuation [6.86 (±2.67) vs 5.29 (±1.89), p=0.58]. For both pre and post LPI 24-hour IOP profiling with the IOP sensor, we found nocturnal and morning IOP peaks compared to evening measurements (Figure 1, p<0.0001, Kruskal Wallis test). Using serial measurement analysis, there was no significant change in median IOP fluctuations after LPI overall (p=0.25) or during specific times of the day (p=0.48); however, morning IOP profile showed a trend of less IOP fluctuation after LPI (Figure 1).
Conclusions
Nocturnal and morning peaks in IOP were found in newly diagnosed PAC subjects. Morning IOP peaks were lower after LPI.
Keywords: 465 clinical (human) or epidemiologic studies: systems/equipment/techniques •
568 intraocular pressure •
578 laser