ICD-10 Code H18.62 – Keratoconus, unstable (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H18.62 – Keratoconus, unstable
What it is
Keratoconus, unstable means the cornea is thinning and bulging in a way that is actively changing. Use this code when the condition is documented as unstable or progressing.
Clinical signs
Clinical features vary; refer to documentation. Typical findings include increasing corneal steepening, worsening irregular astigmatism, and declining vision that suggests progression rather than a stable corneal shape.
When to use this code
Use H18.62 when the provider documents keratoconus as unstable, progressive, or worsening. It may also fit when follow-up notes show change in refraction, topography, or corneal curvature consistent with active disease.
If the record only states keratoconus without stability status, check documentation before coding. Do not assume progression from symptoms alone unless the clinician clearly supports it.
Do not use for
Do not use this code for stable keratoconus or for general corneal ectasia without documented instability. Check documentation if the chart describes another corneal disorder or post-surgical ectasia instead.
Coding tip
Code the instability only when the provider explicitly documents it; otherwise, query for clarification.