Intraocular pressure alterations after visual field testing

To determine whether intraocular pressure (IOP) is significantly altered after visual field (VF) testing in eyes with open-angle glaucoma (OAG).

A prospective clinical trial of 106 OAG patients who had not had any previous surgical interventions. IOP was measured with a non-contact tonometer and refractive error with an auto refractometer. The measurements were made before and immediately after the VF test of the first eye (OD) and the second eye (OS).

The baseline refractive error (spherical equivalent) was -4.13 ± 3.61 diopters (D) OD and -4.05 ± 3.63 D OS. The average VF testing time was 7.5 ± 1.4 min OU. The average baseline IOP was 12.8 ± 2.9 mmHg OD and 12.6 ± 2.8 mmHg OS. After the VF testing OD, the average IOP decreased significantly to 12.3 ± 2.6 mmHg (P = 0.001), but the IOP (12.5 ± 2.6 mmHg) OS was not significantly unchanged (P = 0.190). Following the VF testing OS, the IOP OD was 12.2 ± 2.6 mmHg (P = 0.252) and OS was 12.4 ± 2.7 mmHg (P = 0.487). An elevation of ≥2 mmHg in the IOP after the VF testing was found in 2.8 % of the right eyes and 0.9 % of the left eyes. The refractive error was not significantly changed after the VF testing. Multivariate analysis showed statistically significant correlations between the IOP decrease after the VF testing and the baseline IOP (P = 0.000) and the central corneal thickness (P = 0.034).

In the majority of eyes with OAG, VF testing did not lead to an increase in the IOP. The amount of IOP reduction after VF testing is significantly correlated with the baseline IOP and central corneal thickness.