Systemic toxicity of topical cyclopentolate eyedrops in a child

Sir,

Topically applied ophthalmic medications may sometimes get absorbed into the systemic circulation and lead to significant toxicity. We, herein, report a case of systemic toxicity of topical cyclopentolate eyedrops in a young child.

Case report

A 5-year-old boy presented to paediatric OPD with complaint of progressively diminishing distant vision since 2 years of age. He had normal general physical and systemic examination. Ocular movements and light and accommodation reflexes were bilaterally normal. For fundus examination, he was advised to instill 1% cyclopentolate eyedrops, two drops in each eye, three times at 15 min intervals. However, the father inadvertently instilled it five to six times over 2 h. After another 1 h, he reported again to our OPD with altered behaviour, visual hallucinations, and difficulty in walking. He was disoriented, with ataxic gait and slurred speech. Pupils were widely dilated and fixed (effect of cyclopentolate). Rest of the examination was unremarkable.

Based on these findings and their temporal relation to overdose of cyclopentolate eyedrops, a diagnosis of cyclopentolate toxicity was made. His symptoms gradually resolved over the next 6–8 h. He was discharged after 24 h of observation.

Comment

Cyclopentolate is a synthetic anticholinergic agent and causes rapid-onset cycloplegia.¹ Onset is within 30–60 min and effects last up to a day.² Cyclopentolate eyedrops pass readily through nasolacrimal duct and are well absorbed locally as well as systemically through conjunctiva and nasal mucosa. Systemic absorption also occurs through oropharynx, digestive system, and skin.^{3, 4}

There have been various reports of systemic toxicity following topical application of cyclopentolate eyedrops.^{3, 4, 5, 6, 7} Children are especially prone due to lower body weight. Various manifestations in children include flushing, tachycardia, feeding intolerance, seizures, and drowsiness. Behavioural changes and transient psychotic reactions may also occur.⁷ Physostigmine is the antidote of choice as it readily crosses the blood–brain barrier. Commonly used anticholinesterases such as neostigmine, pyridostigmine, and edrophonium do not cross the blood–brain barrier, and are not useful.⁸ We could not use physostigmine due to non-availability.

This case highlights the importance of caution to be exercised while using topical ophthalmic preparations in children. Physicians should be well aware of their pharmacology and use them judiciously.