Anisocoria is a frequently encountered condition that often requires
neurologic evaluation. Although it may occur with third nerve palsy, other
causes include benign conditions, such as pharmacologic dilation, local iris
sphincter abnormalities, tonic pupil, or sympathetic irritation.1
Unilateral miosis has been reported to result from exposure to cholinesterase
inhibitors found in both flea foggers2 and
pet flea and tick collars.3 We report a
case of unilateral mydriasis associated with exposure to flea spray.
A 3½-year-old boy was brought to the emergency department by
his parents, who noticed that his pupils were of unequal size. There was no
history of trauma, recent illness, medication use, or access to ophthalmic
drops. Further inquiry revealed that the child had been playing with the family
dog, which was recently treated with Sergeant's Flea and Tick Spray (Sergeant's
Pet Care Products, Omaha, Neb). His behavior and activity had been normal.
Vital signs were normal for his age, and results of a pediatrician's examination
revealed no abnormalities other than anisocoria. Ophthalmologic examination
results revealed a visual acuity of 20/30 OU using Allen figures at near.
Anterior segments were normal when examined with a handheld light. Versions,
alignment, and dilated fundus examination results were normal. There was no
evidence of disc edema. Intraocular pressure readings were 13 mm Hg OD and
14 mm Hg OS. Under lighted conditions, the right pupil was 6.5 mm and the
left pupil was 4 mm. In dim light, the right pupil measured 7 mm and the left
pupil measured 5 mm. Both the direct and consensual pupillary light responses
were 1+ OD and 3+ OS. The near response was also 3+ OS and 1+ OD. Results
of computed tomography of the head performed without contrast showed no evidence
of intracranial masses, edema, or dilated ventricles. The mydriasis and pupillary
reactivity of the right eye had improved by the examination on the following
day. Although the child failed to return for a subsequent examination, a telephone
conversation with his mother revealed that the pupil inequality had resolved
and that he was doing fine.
The active pesticide in Seargant's Flea and Tick Spray and related products
permethrin is a type I pyrethroid. Pyrethroids have been found to produce
potent sympathetic activation; local effects, such as paresthesia, have been
reported with skin contamination.4 Additionally, α-adrenergic–mediated
effects have been noted in animal studies using allethrin, another type I
pyrethroid.5 We suggest that the patient's
unilateral mydriasis may have been due to a local effect of permethrin that
occurred after inadvertent rubbing of the eye following skin contamination.
The local sympathetic effect did not alter near vision but produced mydriasis
that was partially overcome by bright light and significantly improved the
following day. To our knowledge, this is the first reported case of mydriasis
occurring in association with exposure to flea pesticide products. It is important
to consider exposure to pesticides during the evaluation of anisocoria since
it may prevent costly and unnecessary imaging in the otherwise healthy patient.
None of the authors have any proprietary interests in the product mentioned
in this article.
Corresponding author and reprints: Charlise A. Gunderson, MD, University
of Texas Medical Branch, Department of Ophthalmology and Visual Sciences,
301 University Blvd, Galveston, TX 77555-0787 (e-mail: firstname.lastname@example.org).
Burns JD, Muller LT, Jenkins PF, Gunderson CA. Unilateral Mydriasis Associated With Exposure to Flea Spray. Arch Ophthalmol. 2002;120(5):665. doi: