ABSTRACT
BACKGROUND: There is a controversy about the concentration of topical phenylephrine recommended for diagnostic or therapeutic mydriasis. Phenylephrine 10% leads to a faster and more pronounced mydriasis but cardio-vascular side-effects like hypertension and arrhythmia have been reported. A maximal pupillary dilatation is a prerequisite for successful cataract surgery. The aim of this study was to evaluate the risk-benefit ratio of phenylephrine 10% in comparison to 5% in the daily practice of the cataract-surgery unit in our clinic by clinical assessment and monitoring of biochemical stress parameters. PATIENTS AND METHODS: 30 informed and consenting patients were randomly allocated to 2 groups of equal size. After a single application of 2 drops of phenylephrine 5% in group 1 and 10% in group 2 respectively and 1 drops of cyclopentolate 1% with neutral pupil (time 0), an ECG was recorded and blood pressure, pulse, oxygen-saturation and pupil size were measured. Simultaneously a blood-sample was taken and the serum-catecholamines adrenaline and noradrenaline were determined by HPLC (High Pressure Liquid Chromatography). These measurements were repeated after 5, 10 and 30 minutes. RESULTS: The mean pupil area after 30 minutes in group 1 was 31.97 (+/- 0.43) mm2 compared to 45.72 (+/- 0.39) mm2 in group 2. Our data showed no other significant variation between the groups: neither clinical monitoring nor catecholamine measurements showed concentration-dependent patterns in blood pressure development or serum levels. No systemic cardiovascular effects were observed. CONCLUSION: These results demonstrate that a controlled application of phenylephrine 10%--under observation of contraindications--yields no increased risk for the occurrence of cardio-vascular side-effects in comparison with phenylephrine 5%. Therefore, we recommend the use of phenylephrine 10% in the described dosage as routine medication for cataract surgery.
