Abstract
Purpose :
The role of intraocular pressure (IOP) fluctuation in glaucoma progression remains controversial. We investigate whether IOP fluctuation is independently associated with the rate of visual field (VF) progression.
Methods :
Participants from the UKGTS with ≥5 VFs were included. Associations between IOP metrics and the mean deviation (MD) rate of progression (RoP) were tested with mixed models. The variables of interest were mean ocular pulse amplitude (OPA), and standard deviation (SD) of diurnal IOP (diurnal fluctuation) and of IOP at all visits (long-term fluctuation). The effect of correlated IOP metrics (Fig1) and multicollinearity were controlled with a principal component analysis of peak and mean IOP during the trial, and baseline (untreated) IOP. The first principal component (PC1) was included as a model covariate. Interactions between variables of interest and time from baseline modelled the variables’ effect on the RoP. Analyses were conducted separately in the two arms.
Results :
213 patients in the placebo arm (mean±SD age: 66.5±10.3 years) and 217 patients in the treatment arm (mean±SD age: 65.2±10.4 years) were included. The median [IQR] of mean IOP, diurnal and long-term fluctuation were, respectively, 18.4 [16.0-21.9], 1.4 [0.9-2.0] and 2.1 [1.6-2.9] mmHg in the placebo arm, and 15.2 [13.2-17.1], 1.3 [0.8-1.7] and 1.9 [1.4-2.6] mmHg in the treatment arm. Mean±SD RoP were -0.32±0.65 and 0.03±0.58 dB/year in the placebo and treatment group, respectively. In the univariable analysis, diurnal and long-term IOP fluctuations were significantly associated with RoP in the placebo arm (p<0.001), and long-term fluctuation in the treatment arm (p=0.047). PC1, combining information of baseline, mean and peak IOPs, were significantly associated with RoP in the placebo (p=0.029) but not in the treatment arm (p=0.95). In the multivariable model, diurnal (placebo estimate: 0.047 dB/year, p=0.60; treatment estimate: 0.046 dB/year, p=0.63) and long-term IOP fluctuations (placebo estimate: -0.124 dB/year, p=0.16; treatment estimate: -0.119 dB/year, p=0.63) were not significantly associated with the RoP (Fig2). OPA was also not associated with RoP (p≥0.11).
Conclusions :
This study confirms that IOP fluctuation is not an independent factor for glaucoma progression and other aspects of IOP may be more informative.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.