Effect of phenylephrine hydrochloride on conjunctival PO2

Phenylephrine hydrochloride eyedrops induce vasoconstriction through alpha-adrenergic mechanisms. Ten subjects underwent a 46% reduction in conjunctival PO2 when 2.5% phenylephrine eyedrops were administered. Compared with a control group, this reduction was significant. The induced conjunctival hypoxia lasted about 80 minutes. These findings suggest a number of clinical implications.