Mydriasis
Mydriasis refers to dilation of the pupil beyond its normal size. In clinical practice, it is almost always induced deliberately so that an ophthalmologist or optometrist can examine the retina, optic nerve, and lens clearly. The pupil can also dilate as a drug side effect, after head trauma, or due to certain neurological conditions.
Medicines used to treat Mydriasis
What triggers pupil dilation and how it is managed
Clinically induced mydriasis relies on short-acting anticholinergic or adrenergic eye drops. Two agents commonly used across eye-care clinics in Singapore, Hong Kong, Malaysia, and Thailand are cyclopentolate and tropicamide. Cyclopentolate acts for several hours and is preferred when the examiner also needs to paralyse the focusing muscle (cycloplegia). Tropicamide has a shorter duration and is often chosen when only brief dilation is needed.
During dilation, bright light becomes uncomfortable and near vision blurs temporarily. Both effects resolve as the drops wear off. Driving or operating machinery while dilated is inadvisable. If one pupil suddenly dilates without any drops being used, particularly alongside headache, double vision, or drooping of the eyelid, prompt medical review is warranted.