[Phenylephrine 10% eye drop action in the eyelid position in healthy subjects]

To determine the upper and lower eyelid position with a single drop of 10% phenylephrine in normal individuals and observe positional lid changes in upper and lower lids of the opposite eye.

Prospective observational study including 24 healthy subjects of both genders (age range: 20-39 yrs) submitted to instillation of a single drop of 10% phenylephrine in the upper fornix of one randomly chosen eye. A video camera recorded the images of both eyes before and after eye drop application at 3, 10, 15, 30, 45 and 60 minutes. The images were digitally processed and edited to analyze lid measurements (upper lid height: distance between the highest upper margin lid point and a horizontal line traced from the medial to the lateral canthus; lower lid height: distance between the lowest margin lid point and the above-mentioned line).

Before and after drug instillation, upper lid height was significantly different (p<0.001) at all moments with a mean elevation of 0.79 mm. The lower lid height changed too with a mean retraction of 0.37 mm. In the fellow eye upper lid drop was observed at almost all moments with the lowest value at 3 minutes (mean reduction of 0.68 mm) and elevation (0.37 mm) of lower lid.

This experiment showed that a single drop of 10% phenylephrine acted not only on the upper eyelid but also on lower lid of the tested eye. Control mechanism of lid opening and closing changed upper and lower lid positioning of the opposite eye in healthy subjects.