Abstract
Purpose:
To determine the short-term effect of topical ophthalmic proparacaine hydrochloride 0.5% on intraocular pressure in humans.
Methods:
Case control study. Subjects: 25 normal healthy adults. One drop of proparacaine hydrochloride 0.5% was instilled into one eye determined at random. Tonometry was performed on both eyes using the iCare rebound tonometer at baseline, 2 minutes and 5 minutes.
Results:
Average age was 29.6 years (SD 9.1, range 22-56). 15 subjects were female and 10 were male. Proparacaine was instilled into 10 right eyes and 15 left eyes (experimental eye). Mean basal IOP was 13.9 ± SEM 0.7 mmHg in experimental eyes and 13.9±0.8 mmHg control eyes. At 2 minutes, the IOP was 13.9±0.6 mmHg and 13.4±0.7 mmHg in the experimental and control eyes, respectively (p=0.2). At 5 minutes, the IOP was 13.6±0.7 mmHg and 13.9±0.7 mmHg in the experimental and control eyes, respectively (p=0.3). Power analysis using 1-β = 0.8 and α<br /> = 0.05 reveals sufficient power to detect a change of 2.1 mmHg.
Conclusions:
This study failed to detect a significant effect of topical proparacaine on IOP as measured using the iCare rebound tonometer. There are several possible reasons, including small sample size, short monitoring period, and suitability of rebound tonometry. Further investigation is required to address the reliability of the data by increasing the n value, (n=52), to determine the degree to which topical proparacaine influences IOP changes. In addition, because effects of proparacaine lasts 15-20 minutes, by extending the experimental time to include an IOP<br /> measurement at 10 minutes, we hope to better understand the short-term trend of IOP after instillation. The iCare tonometer was consistent in its measurements with a standard deviation of ~0.7 mmHg across the measurements, thus the rebound tonometer is sufficient and does not contribute to a significant change in IOP.