Tonic pupil, unspecified eye

This code signifies a tonic pupil, characterized by a pupil that reacts slowly and incompletely to light and accommodation, often remaining dilated. It indicates a dysfunction of the parasympathetic innervation to the iris sphincter muscle. This specific code is used when the affected eye is not specified.

Apply this code when documentation clearly states "tonic pupil" without specifying laterality (e.g., "patient presents with tonic pupil"). It is appropriate when the physician has not identified whether the condition affects the right, left, or both eyes.

• Avoid using this code if documentation specifies laterality (e.g., "tonic pupil, right eye" or "tonic pupil, left eye"); use the more specific H57.051 or H57.052.
• Ensure the medical record supports the diagnosis of tonic pupil, often including findings from a pupillary exam.
• Do not confuse with other pupillary abnormalities like anisocoria (R29.891) or Horner's syndrome (G90.2).