Abstract
Abstract: :
Purpose:Phenylephrine 10% (PE10), a sympatomimetic agent, is used for pupil dilation. It is a potent vasoconstrictor as seen by vessel blanching in the conjunctiva. Aim of our study was to determine, whether a single drop of topical PE10 is able to influence retinal branch artery diameter. Influence of sympatomimetics on retinal vessels should be most pronounced in arteries, because of their active regulation role in maintaining perfusion pressure. Methods:Retinal branch artery diameter after PE10 application was assessed in 26 young healthy volunteers between the age of 22 to 45 years (mean 28.4 + 8.2 years). Volunteers were examined by Retinal Vessel Analyzer (RVA) (Imedos Ltd, Germany) a device for automatic on-line measurement of retinal vessel diameter along a vessel segment. Changes in arterial diameter were observed for 28 minutes after application of 1 drop of PE10. Every 2 minutes pulse and systemic blood pressure were taken. A control group of 5 healthy volunteers was examined with application of liquid tears. Changes in blood pressure of more than 10 mmHg were considered significant. Results:Control group: No significant change in blood pressure, significant arterial dilation (1), significant decrease in blood pressure, corresponding dilation in arterial diameter (2), significant change in blood pressure, no change in vessel diameter (2). PE10 group: Significant change in blood pressure 3 (11.5%) volunteers (2 arterial dilations, 1 no change). 20 volunteers (77 %) with no systemic blood pressure reaction. These volunteers showed vessel constriction of 6.9%3.7% (sign test p=0.003) after 13.13.3min (10); no significant change in vessel diameter (p=0.19) compared with baseline (6); and vessel dilation of 6.8%2.8% (p=0.001) after 11.21.7min (4). 3 (11.5%) volunteers showed a mixed reaction: significant drop in blood pressure and dilation (1), constriction (1) and no reaction (1) herewith. Conclusion:Topical single application of PE10 was able to alter retinal branch arterial diameter in this study. Factors predicting an individual’s reaction to PE10 could not be determined. Despite our expectations few volunteers reacted with blood pressure changes. PE10 evoked a vessel reaction in most subjects exceeding the normal changes observed in the control group. Whether diameter change was a reaction to change in systemic parameters or a local vessel regulatory response could not be determined. In blood flow studies in the eye attention should be paid to the mydriatic agent, since PE10 is able to induce vascular diameter changes.
Keywords: 390 drug toxicity/drug effects • 430 imaging/image analysis: clinical • 554 retina