Abstract
Purpose: :
To investigate the effect of Bimatoprost on intraocular pressure (IOP) fluctuation caused by change in posture from a sitting to supine position.
Methods: :
This prospective observational study comprised 14 eyes of healthy volunteers with no known ocular or cardiovascular disease enrolled from the outpatient eye clinic at the University of South Carolina. Baseline IOP was measured first in a seated position and again after five minutes in a supine position using a hand-held tonometer (Medtronic Solan Tono-Pen® XL). Three measurements, each with a 5% confidence interval, were obtained and averaged for both sitting and supine positions. Following a one-week period of treatment with daily Bimatoprost, IOP measurements were repeated in both sitting and supine positions. Central corneal thickness (CCT) was also measured using a Pachmate DGH pachymeter.
Results: :
The mean baseline IOP in the sitting and supine positions was 12.9 ± 1.7 mmHg and 14.7 ± 2.3 mmHg, respectively, with a mean difference between sitting and supine IOP (ΔIOP) of 1.8 ± 0.8 mmHg (p < 0.040). The mean IOP after treatment with Bimatoprost was 10.3 ± 1.7 mmHg sitting and 12.0 ± 1.6 mmHg supine, representing a ΔIOP of 1.7 ± 0.5 mmHg (p < 0.039). The mean CCT was 574.1 ± 34.0 µm. Compared to the baseline IOP, the IOP in both postures was significantly reduced after administration of Bimatoprost with mean decreases of 2.7 ± 1.1 mmHg (p < 0.015) sitting and 2.9 ± 1.6 mmHg (p < 0.022) supine. The observed decrease in ΔIOP following treatment with Bimatoprost was not statistically significant (p < 0.359).
Conclusions: :
Change in posture from a sitting to supine position causes a significant increase in IOP. Treatment with Bimatoprost significantly decreases IOP in both postures; however, the magnitude of IOP elevation accompanying change in posture does not appear to be significantly affected. Further study is necessary and underway to determine the influence of Bimatoprost on IOP fluctuation with postural changes in eyes with glaucoma, realizing that such patients may be at increased risk for progressive damage related to IOP elevation as well as changes in ocular perfusion pressure.
Keywords: intraocular pressure