ICD-10 Code H16.399 – Other interstitial and deep keratitis, unspecified eye (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H16.399 – Other interstitial and deep keratitis, unspecified eye
What it is
This code identifies keratitis involving the deeper corneal layers when the eye is not specified. Use it for interstitial or deep corneal inflammation that is not otherwise classified.
Clinical signs
Findings may include corneal haze, stromal inflammation, redness, pain, photophobia, and reduced vision. Clinical features vary; refer to documentation.
When to use this code
Use H16.399 when the record documents interstitial or deep keratitis but does not identify the affected eye. It also fits when the provider describes deep corneal inflammation without a more specific subtype. Check documentation if the note names the right or left eye.
Do not use for
Do not use this code for superficial keratitis, corneal ulcer, or a clearly documented specific keratitis type. If the eye is identified, choose the laterality-specific code instead.
Coding tip
Verify whether the provider documented laterality before assigning this unspecified-eye code.