Apraclonidine Is an Eye Opener

Journal Highlights

Frontiers in Ophthalmology
Published online Aug. 9, 2022

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Apraclonidine reverses anisocoria and is often preferred to cocaine for con­firming Horner syndrome. It also raises the upper eyelid and thus may help if the pupillary response to pharmaco­logic testing is equivocal. Fierz et al. conducted a quantitative study of eyelid aperture effects in Horner syndrome and found changes in eyelid opening to be a promising diagnostic adjunct.

Their investigation included adults referred to the neuro-ophthalmology unit of a university hospital for evalu­ation of anisocoria during a three-year period. Qualifying participants received binocular pupillometry before and after testing with 1% apraclonidine eyedrops (one drop in each eye). Pupillometry was performed on each eye simultane­ously and in synchrony.

The diagnosis of Horner syndrome was based solely on apraclonidine response, irrespective of any causative lesion, ptosis, or heterochromia. Pupil­lary size was measured before and after instillation of apraclonidine and was expressed as the median size from three to four seconds after lights off, derived from the pupillometry reading. The apraclonidine test was deemed positive (indicating Horner syndrome) if the smaller pupil dilated and the larger pupil constricted.

Infrared video recordings obtained during pupillometry were analyzed by customized software. Eyelid aperture was measured manually and reflected the distance between the two eyelids, using a pre-set vertical line at the pupillary center. These measurements were attained in a fixed interval, within the first five seconds of lights off while blinking was avoided. Several readings from individual pupillometry cycles were averaged, and inter-eye differences in vertical aperture were calculated. Receiver operating characteristic curves were used to determine the optimal cutoff value for eyelid aperture change before and after apraclonidine.

Two of 38 qualifying participants were excluded because dermatochalasis obscured their eyelid margin, prevent­ing accurate measurements. Half of the remaining 36 patients had a positive result with apraclonidine, indicating Horner syndrome. The others were considered to have physiologic anisoco­ria. A decrease in inter-eye aperture dif­ference of at least .42 mm characterized Horner syndrome and distinguished it from physiological anisocoria, with sensitivity of 80% and specificity of 75%. The mean increase in eyelid aper­ture was 2.01 mm in eyes with Horner syndrome and 1.08 mm in unaffected eyes. The eyelid-raising effect of apra­clonidine was more pronounced in eyes with a sympathetic denervation deficit.

“Measuring eyelid aperture on pup­illometry recordings may improve the diagnostic accuracy of apraclonidine testing in Horner syndrome,” said the authors. They believe that combining pupil and aperture measurements could further optimize accuracy

The original article can be found here.