How to chart a neuro assessment

1. Dim or keep ambient light the same each check so size comparisons are fair.
2. Inspect size (mm if you have a gauge), shape, and symmetry at rest before any light.
3. Use a bright, narrow penlight beam from the side — not a wide household flashlight (wide beams can fake a “direct” response by lighting the other eye).
4. Check direct constriction, then consensual (opposite eye). Repeat other side.
5. If taught: accommodation — near object (constrict) then far (dilate).
6. Note meds that shrink pupils (opioids) or affect reactivity; document if a pupillometer was used.

Bedside pearl: About 1 mm of lifelong anisocoria can be normal for some people — compare to their baseline and the rest of the exam before panicking. New unequal + LOC change is a different story.

• Pupil size balances parasympathetic constriction (CN III pathways) and sympathetic dilation.
• Light hits the retina → midbrain → both pupils normally respond.
• Unequal pupils can be a harmless baseline (physiologic anisocoria) or a sign of nerve compression, eye trauma, drops, or other intracranial problems.
• Context and change from the patient’s baseline decide urgency.