ICD-10 Code H18.629 – Keratoconus, Unstable, Unspecified Eye (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H18.629 – Keratoconus, unstable, unspecified eye
What it is
This code identifies keratoconus in an unspecified eye when the condition is unstable. It means the cornea is progressively thinning or changing shape, and the record does not specify which eye.
Clinical signs
Typical findings include irregular corneal steepening, blurred or distorted vision, and increasing astigmatism. Clinical features vary; refer to documentation if the chart does not clearly describe instability.
When to use this code
Use H18.629 when the clinician documents unstable keratoconus but does not identify the right or left eye. It also fits when the note confirms ongoing progression or change in corneal shape without laterality. If the record names a specific eye, code that laterality instead.
Do not use for
Do not use this code for stable keratoconus or for corneal disorders that are not keratoconus. Do not assign it when documentation specifies a different eye code or when the diagnosis is uncertain. Check documentation.
Coding tip
Confirm both instability and laterality in the ophthalmology note before coding; unspecified eye codes should be used only when the record truly lacks laterality.