PHENYLEPHRINE/COOPER contains a mydriatic agent. It is used to enlarge the pupil of your eye. Your doctor or eye specialist may use it to examine your eye more closely or as part of a treatment program. PHENYLEPHRINE/COOPER 5 % is indicated for children, adults and the elderly. PHENYLEPHRINE/COOPER 10% is not indicated for children or the elderly, as this concentration is too strong. The doctor or eye specialist will use an alternative medicine in these patients.