Ocular effects and systemic absorption of cyclopentolate eyedrops after canthal and conventional application

Ocular effects and plasma concentrations of cyclopentolate were studied in 8 volunteers after eyedrop application with two methods. While recumbent two 30 microliters drops of 1% cyclopentolate hydrochloride were instilled in randomized order either conventionally to the lower conjunctival cul-de-sac or on the inner canthus with eyes closed, followed by immediate opening of the eyes. The cycloplegic responses as well as the extent and time of maximal mydriasis did not differ significantly between the two methods. None of the parameters describing the systemic absorption of the drug differed between the treatment groups. Conventionally applied drops caused slightly longer subjective discomfort. Instilling eyedrops on the inner canthus with eyes closed is an alternative method to deliver ocular cyclopentolate with similar efficacy and safety as the conventional technique. This method could be useful especially when treating non-cooperative children.