Tonic pupil, bilateral

This code describes Adie's tonic pupil affecting both eyes, a neurological condition characterized by a pupil that is larger than normal, reacts slowly to light, and constricts poorly to accommodation. It results from damage to the parasympathetic innervation of the pupil, often idiopathic or post-viral.

Use this code when documentation explicitly states "tonic pupil, bilateral" or "Adie's pupil, bilateral." This diagnosis is typically made during an ophthalmological or neurological examination, noting the characteristic pupillary light-near dissociation and slow redilation.

• Ensure the documentation specifies bilateral involvement; separate codes exist for unilateral cases.
• Do not confuse with other pupillary abnormalities like Argyll Robertson pupil or Horner's syndrome, which have distinct etiologies and presentations.
• Consider coding any underlying systemic conditions if identified as the cause of the tonic pupil.