section name header

General Information ⬇

Classification

  1. The abnormal pupil is constricted.
    • Unilateral exposure to a miotic agent (e.g., pilocarpine).
    • Iritis: Eye pain, redness, and anterior chamber cell and flare.
    • Horner syndrome: Mild ptosis on the side of the small pupil. See 10.2, HORNER SYNDROME.
    • Argyll Robertson (i.e., syphilitic) pupil: Always bilateral, irregularly round miotic pupils, but a mild degree of anisocoria is often present. See 10.3, ARGYLL ROBERTSON PUPILS.
    • Long-standing Adie pupil: The pupil is initially dilated, but over time may constrict. Hypersensitive to pilocarpine 0.125%. See 10.4, ADIE (TONIC) PUPIL.
  2. The abnormal pupil is dilated.
    • Iris sphincter muscle damage from trauma or surgery: Torn pupillary margin or iris transillumination defects seen on slit lamp examination.
    • Adie (tonic) pupil: The pupil may be irregular, reacts minimally to light, and slowly and tonically to accommodation. Hypersensitive to pilocarpine 0.125%. See 10.4, ADIE (TONIC) PUPIL.
    • Third cranial nerve palsy: Always has associated ptosis and/or extraocular muscle palsies. See 10.5, ISOLATED THIRD CRANIAL NERVE PALSY.
    • Unilateral exposure to a mydriatic agent: Cycloplegic drops (e.g., atropine), scopolamine patch for motion sickness, ill-fitting mask in patients on nebulizers (using ipratropium bromide), and possible use of sympathetic medications (e.g., pseudoephedrine). If the mydriatic exposure is recent, pupil will not react to pilocarpine 1%.
  3. Physiologic anisocoria: Pupil size disparity is the same in light as in dark, and the pupils react normally to light. The size difference is usually, but not always, <2 mm in diameter.
NOTE:

In cases of inflammation resulting in posterior synechiae formation, the abnormal pupil may appear irregular, nonreactive, and/or larger.

Work Up ⬆

Workup
  1. History: When was the anisocoria first noted? Associated symptoms or signs? Ocular trauma? Eye drops or ointments? Syphilis history (or risk factors)? Old photographs?
  2. Ocular examination: Try to determine which pupil is abnormal by comparing pupil sizes in light and in dark. Anisocoria greater in light suggests the larger pupil is abnormal; anisocoria greater in dark suggests the smaller pupil is abnormal. Test the pupillary reaction to both light and near. Evaluate for the presence of an afferent pupillary defect. Look for ptosis, evaluate ocular motility, and examine the pupillary margin with a slit lamp.
    • If the abnormal pupil is small, a diagnosis of Horner syndrome may be confirmed by a cocaine or apraclonidine test (see 10.2, HORNER SYNDROME).
    • If the abnormal pupil is large and there is no sphincter muscle damage or signs of third cranial nerve palsy (e.g., extraocular motility deficit, ptosis), the pupils are tested with one drop of pilocarpine 0.125%. Within 10 to 15 minutes, an Adie pupil will constrict significantly more than the fellow pupil (see 10.4, ADIE [TONIC] PUPIL).
    • If the pupil does not constrict with pilocarpine 0.125%, or pharmacologic dilation is suspected, pilocarpine 1% is instilled in both eyes. A normal pupil constricts sooner and to a greater extent than the pharmacologically dilated pupil. An eye that recently received a strong mydriatic agent such as atropine usually will not constrict at all.
NOTE:

For an acute Adie pupil, the pupil may not react to a weak cholinergic agent.

See 10.2, HORNER SYNDROME, 10.3, ARGYLL ROBERTSON PUPILS, 10.4, ADIE (TONIC) PUPIL, and 10.5, ISOLATED THIRD CRANIAL NERVE PALSY.

Eyelid position, globe position (e.g., to rule out proptosis), and extraocular motility MUST be evaluated when anisocoria is present (see Figure 10.1.1).

10-1.1 Flow diagram for the workup of anisocoria.!!flowchart!!

Gervasio-ch010-image001

*Hydroxyamphetamine should not be used within 24 to 48 hours of cocaine or apraclonidine to avoid possible interference with each other.

(Modified from Thompson HS, Pilley SF. Unequal pupils. A flow chart for sorting out the anisocorias. Surv Ophthalmol. 1976;21:45-48, with permission.)