Editor,—Cyclopentolate 1% is the drug most commonly used to obtain paediatric pupil dilatation and cycloplegia. It is widely disliked by children and ophthalmic staff because of the severe stinging instillation may produce. As a result many children develop a negative association with the clinic, and become distressed and uncooperative before drop instillation and during subsequent examinations. To try to reduce this discomfort, previous instillation of the local anaesthetic proxymetacaine has been advocated in a single study,1 which reported significant benefit. However, this was a retrospective study, with the particular limitation of using parental recall of their child's distress a year previously, as the measure of the pain experienced with the use of cyclopentolate alone. We therefore considered that more data were required before the use of proxymetacaine is included in routine cycloplegia.

Because cyclopentolate is unstable at neutral pH, preparations are acidified with dilute hydrochloric acid to around pH 4 so that stinging on instillation might …