Abstract
Purpose To compare the impact of visual field (VF) testing on intraocular pressure (IOP) change trends between healthy subjects and glaucoma patients. Methods We recruited healthy volunteer subjects who did not have previous ocular diseases and open-angle glaucoma patients who were medically controlled well. IOP in both eyes of each participant was measured by using a noncontact tonometer at five time points: before, immediately after (0 minute), and 10, 30, and 60 minutes after the standard automated perimetry. Repeated measures ANOVA was used to analyze the effect of VF testing on IOP change trends in healthy and glaucoma eyes. Results Forty healthy subjects (80 eyes) and 31 open-angle glaucoma patients (62 eyes) were included for the study. The baseline IOP of healthy and glaucoma eyes was 16.11 ± 3.01 mmHg and 15.78 ± 3.57 mmHg, respectively. After the VF testing, the IOP in healthy eyes was decreased by 1.5% at 0 minute, 6.5% at 10 minutes (P < 0.001), 6.6% at 30 minutes (P < 0.001), and 7.0% at 1 hour (P < 0.001), indicating that this reduction was sustained for at least 1 hour. However, the IOP in glaucoma eyes was increased by 12.7% at 0 minute (P < 0.001) and, then, returned towards initial values 1 hour after the VF testing. Conclusions IOP change trends after VF field testing between healthy subjects and glaucoma patients were quite different. VF testing led to a mild and relatively sustained IOP decrease in healthy subjects, whereas IOP in open-angle glaucoma patients tended to significantly increase immediately after VF testing and, then, returned to pretest values after 1 hour. These findings indicate that the factors of VF testing should be considered in the clinical IOP measurements.
Highlights
As elevated intraocular pressure (IOP) is a major risk factor in the development of glaucoma that can severely threaten our visual function [1,2,3], accurate IOP measurements are very essential for daily management of this disease [4]
We found that 13.8% and 7.5% of the healthy eyes experienced more than 10% and more than 20% IOP increase, whereas 59.7% and 27.4% of the glaucoma eyes experienced more than 10% and more than 20% IOP increase immediately after the Visual field (VF) testing (Figure 2)
Recupero et al [8] found that VF testing led to a transient IOP increase of more than 2 mmHg in 44.7% of primary open-angle glaucoma (POAG) patients, but no IOP change in healthy subjects
Summary
As elevated intraocular pressure (IOP) is a major risk factor in the development of glaucoma that can severely threaten our visual function [1,2,3], accurate IOP measurements are very essential for daily management of this disease [4]. IOP is a highly variable and dynamic parameter and is affected by numerous factors, for example, measurement factors (such as tonometer and examiner), ocular factors (such as corneal thickness, corneal hysteresis, and dehydration), and individual factors (such as accommodation, circadian cycle, body position, mental stress, and blood pressure) [5, 6]. It is, of paramount significance for ophthalmologists to know about IOP variations and their influences in the clinical treatment and follow-up of glaucoma patients. As physiological variations exist in IOP [5], such few measuring time points could be insufficient to reflect real IOP change trends after VF testing and might be the reason of contradictory results in previous studies
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