INTRAOCULAR PRESSURE MEASUREMENTS IN STANDING POSITION WITH A REBOUND TONOMETER

It has been established that body position can play an important role in intraocular pressure (IOP) fluctuation. IOP has been previously shown to significantly increase when lying down, compared to sitting; this type of investigation has not been extensively reported for the standing (ST) position. Therefore, this study aims to look for eventual significant IOP changes while ST, sitting, and lying down.

University Eye Clinic, Department of Medicine and Surgery, University of Salerno, Italy.

An Icare PRO was used to measure the IOP of 120 eyes of 60 healthy individuals, with age ranging from 21 to 55 years (mean 29.22 ± 9.12 years), in sitting, supine and ST positions; IOP was measured again, 5 minutes after standing (ST‐5m). Statistical evaluation was performed with a paired Student’s t‐test and a p-value less then 0.05 was considered statistically significant.

Mean IOP difference between sitting and ST position was 0.39 ± 1.93 mmHg (95% CI: 0.04 to 0.74 mmHg) (p = 0.027); between sitting and ST‐5m, it was −0.48 ± 1.79 mmHg (95% CI: −0.8 to −0.16 mmHg) (p = 0.004); between the sitting and supine position, it was −1.16±1.9 mmHg (95% CI: −1.5 to −0.82 mmHg) (p < 0.001); between the supine and ST position, it was 1.55 ± 2.04 mmHg (95% CI: 1.18 to 1.92 mmHg) (p < 0.001); between supine and ST‐5m, it was 0.68 ± 1.87 mmHg (95% CI: 0.34 to 1.02 mmHg) (p < 0.001); and between ST‐5m and ST, it was 0.94 ± 1.95 mmHg (95% CI: 0.58 to 1.29 mmHg) (p < 0.001). Mean axial eye length was 24.45 mm (95% CI: 24.22 to 24.69 mm), and mean central corneal thickness was 535.30 μm (95% CI: 529.44 to 541.19 μm).

Increased IOP in the ST‐5m position suggests that IOP measurements should be performed in this position too. The detection of higher IOP values in the ST‐5m position than in the sitting one, may explain the presence of glaucoma damage or progression in apparently normal‐tension or compensated patients.