Intraocular pressure control and visual field changes in primary angle closure disease: The CUHK PACG Longitudinal (CUPAL) study

Purpose To determine the relationship of intraocular pressure (IOP) control with subsequent visual field (VF) deterioration in patients with primary angle closure disease (PACD). Methods 419 PACD eyes from 240 Chinese patients were included. Mean IOP and IOP fluctuation were calculated as the average and SD divided by mean IOP, respectively, of all the IOP measured in the initial 18 months for assessment of IOP control. The relationship between IOP control and subsequent VF parameters over time was examined using linear mixed models. VF deterioration was defined as IOP control associated with decreased VF parameters over time with a p value <0.05. We calculated the average of the mean IOPs and IOP fluctuations in the cohort and used these two average values as a cut-off point to define high-threshold (≥average value) or low-threshold (<average value) for mean IOP and IOP fluctuation for each PACD eye, respectively. Results Greater IOP fluctuation was significantly associated with VF deterioration, independent of mean IOP (mean deviation (MD) β=-6.36, p=0.03; VF index β=-16.41, p=0.04; and cataract-adjusted MD β=-6.96, p=0.02). In the categorical analysis, those with both high-threshold mean IOP and high-threshold IOP fluctuation had the most rapid VF deterioration, compared with eyes with low-threshold IOP fluctuation (p<0.05). Among eyes with high-threshold mean IOP, eyes with high-threshold IOP fluctuation had faster rate of VF deterioration compared with eyes with low-threshold IOP fluctuation (p=0.01). Conclusions IOP fluctuation was a significant and independent predictor for subsequent VF deterioration in eyes with PACD.