ICD-10 Code H57.05 – Tonic pupil (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H57.05 – Tonic pupil
What it is
Tonic pupil is an abnormal pupil response in which one pupil reacts slowly or poorly to light and accommodation. It usually reflects a problem with the parasympathetic nerve supply to the iris.
Clinical signs
Typical findings include a dilated pupil with sluggish constriction, poor redilation, and light-near dissociation. Clinical features vary; refer to documentation.
When to use this code
Use H57.05 when the record specifically documents tonic pupil, Adie pupil, or a tonic pupillary response. Apply it for isolated pupillary abnormality when the clinician identifies this condition as the diagnosis. Check documentation if the note only mentions anisocoria or a general pupillary defect.
Do not use for
Do not use this code for nonspecific pupil changes without a documented tonic pupil diagnosis. Avoid it when the finding is due to trauma, medication, or another documented ocular or neurologic disorder.
Coding tip
Code the documented diagnosis exactly and verify laterality or associated cause only if the provider states it.