Abstract
Purpose: :
To measure intraocular pressure (IOP) in the sitting, supine and 30 degrees inverted (Trendelenburg) position in open angle glaucoma (OAG) patients and normal controls.
Methods: :
Twenty six primary open angle and peudoexfoliation glaucoma patients under medical treatment and fourteen healthy controls were included. None of the subjects had a history of other ocular pathology, diabetes, major cardiovascular disease apart from mild hypertension, or previous antiglaucoma surgery. IOP was measured in one eye with a Perkins tonometer and blood pressure was measured with a sphygmomanometer in the sitting, supine and Trendelenburg position consecutively. A period of five minutes was allowed before measurements were performed on assumption of each position.
Results: :
There was no difference in age between the two groups. Mean IOP in the OAG group was 13.8±2.9mmHg in the sitting position increasing to 16.7±3.4 mmHg in the supine and 18.8±4.0 mmHg in the Trendelenburg position (repeated measures ANOVA, p<0.05 for all comparisons). IOP was 13.1±1.8 mmHg in the control group, increasing to 14.4±2.6 mmHg and 15.5±2.6 mmHg (ANOVA, p<0.05 for all comparisons) for the same positions. No significant difference between the two groups was found in IOP in the sitting position (Mann-Whitney test, p=0.8). There was a bigger IOP increase from baseline in the OAG patients compared to the control group on assuming both the supine (2.9±1.7 mmHg versus 1.3±1.4 mmHg, Mann-Whitney, p=0.04) and the Trendelenburg position (5.0±2.5 mmHg versus 2.4±1.7 mmHg, p<0.01). ANOVA for the intraindividual and between groups comparisons revealed no difference in mean arterial pressure with changing position.
Conclusions: :
IOP increases when assuming the supine and the Trendelendurg position in both groups. However, medically treated OAG patients exhibit a bigger posture-related IOP change compared to healthy subjects, especially in the Trendelenburg position.
Keywords: intraocular pressure • blood supply • outflow: trabecular meshwork