Posture-induced changes in intraocular pressure: comparison of pseudoexfoliation glaucoma and primary open-angle glaucoma

Purpose

The objective of this study was to evaluate and compare the IOP values in the sitting and supine positions in primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) patients. We also investigated possible relationships between the level of visual field damage and postural IOP change.

Methods

Twenty-nine patients with POAG and 32 patients with PXG were recruited to the study. An Icare PRO tonometer was used to measure IOP in the sitting and supine positions. Intraocular pressure in the sitting position was also measured with a Goldmann applanation tonometer (GAT). Humphrey field analyzer 750 data taken within the previous 3 months were obtained and analyzed.

Results

The mean difference between the GAT and the Icare PRO tonometer readings was 0.12 ± 0.8 mmHg, and the tonometers were in close agreement (r = 0.964; P < 0.0001). The mean Icare PRO IOP in the sitting position was 16.6 ± 3.3 mmHg in the POAG group and 14.9 ± 2.7 mmHg in the PXG group. The average rise was 1.7 ± 1.2 mmHg in the POAG group and 2.9 ± 1.9 mmHg in the PXG group. The difference in IOP between the sitting and supine positions was significant between the groups (P = 0.001). The ?IOP was negatively correlated with both the mean deviation and the visual field index (P < 0.0001 for both). The ?IOP and pattern standard deviation were positively correlated (P < 0.0001).

Conclusions

A higher increase in IOP was observed in PXG patients from the sitting to the supine position than in POAG patients. Postural variation in IOP was found to be associated with the severity of visual field damage.