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Updated: Jun 3, 2026
07:26
Assessing Pupil-linked Changes in Locus Coeruleus-mediated Arousal Elicited by Trigeminal Stimulation
Published on: November 26, 2019
Apraclonidine and my pupil
Melissa Cambron1, Heidi Maertens, Luc Crevits
1Ghent University, and Department of Neurology, Ghent University Hospital, Ghent, Belgium. Melissa.cambron@vub.ac.be
Summary
Apraclonidine 1% causes miosis in healthy eyes, peaking 30-60 minutes post-instillation. This effect differs from its use in diagnosing Horner
Area of Science:
- Ophthalmology
- Pharmacology
Background:
- Apraclonidine 1% is used to diagnose Horner's syndrome by causing mydriasis in affected eyes due to denervation supersensitivity.
- However, recent studies suggest apraclonidine may have a mild miotic effect in healthy eyes.
Purpose of the Study:
- To investigate the effect of apraclonidine on pupillary parameters in healthy eyes.
- To determine the optimal time for evaluating apraclonidine's effect on the pupil.
Main Methods:
- Infrared pupillography was used to measure pupil diameter and light response.
- Measurements were taken at various intervals up to 360 minutes after instilling apraclonidine 1% in one eye of 14 healthy volunteers.
Main Results:
- Apraclonidine 1% caused relative miosis in the treated eye, most significantly at 30 and 60 minutes post-instillation.
- The amplitude of light-induced pupil constriction increased in the apraclonidine-treated eye.
- No significant changes were observed in pupil latency or constriction/redilation velocity.
Conclusions:
- Apraclonidine 1% induces relative miosis in healthy subjects, with the effect most pronounced between 30-60 minutes.
- This miotic effect is attributed to a stronger alpha-2 agonistic effect than alpha-1 agonistic effect in healthy eyes.
- In contrast, alpha-1 agonistic effects dominate in Horner's syndrome patients due to receptor supersensitivity, causing mydriasis. This highlights the importance of instilling apraclonidine in the unaffected eye for accurate Horner's syndrome diagnosis.
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