ICD-10 Code H57.04 – Mydriasis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H57.04 – Mydriasis
What it is
Mydriasis means abnormal dilation of one or both pupils. Use this code when the record documents enlarged pupils as the primary finding, not a broader eye disorder.
Clinical signs
Typical findings include a visibly enlarged pupil with reduced constriction to light. Clinical features vary; refer to documentation if the cause, laterality, or associated neurologic findings are not clearly stated.
When to use this code
Use H57.04 when the clinician documents mydriasis as a diagnosis or reason for evaluation. It may apply when the chart notes pupillary dilation from medication, trauma, neurologic concern, or an unexplained eye examination finding. Confirm whether the record identifies a separate underlying condition that should be coded instead.
Do not use for
Do not use this code for normal pupil enlargement in dim light or for general eye symptoms without documented mydriasis. Check documentation if the record describes anisocoria, pupil abnormality, or another specific ocular disorder instead.
Coding tip
Code the documented pupil dilation only when it is clearly stated; if the cause is specified, sequence and add the underlying condition as appropriate.