Dissociated nystagmus

This code describes a specific type of involuntary eye movement where the two eyes move in different directions or at different amplitudes. It signifies a disconjugate nystagmus, meaning the oscillations of each eye are not symmetrical or coordinated. This condition often indicates a neurological underlying cause.

Use this code when documentation explicitly states "dissociated nystagmus" or describes disconjugate, asymmetric, or unequal nystagmus affecting both eyes. This diagnosis is typically made by an ophthalmologist or neurologist based on clinical examination findings.

• Differentiate from conjugate nystagmus (H55.01-H55.03) where both eyes move in the same direction.
• Always look for documentation specifying the type of nystagmus (e.g., pendular, jerk) and laterality if applicable, although dissociated implies both eyes.
• Code any underlying neurological conditions (e.g., multiple sclerosis, brainstem lesion) as primary diagnoses when appropriate, with nystagmus as a secondary manifestation.