2027 ICD-10-CM Diagnosis Code H16.9Unspecified keratitis
H16.9 is a billable ICD-10-CM diagnosis code for unspecified keratitis. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 124 through 125. The code is not accepted as a principal diagnosis by the Medicare Code Editor. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cornea and external disease.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for H16.9.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Autosomal dominant ichthyosis
- Autosomal recessive keratitis-ichthyosis-deafness syndrome
- Bilateral fungal keratitis
- Bilateral keratitis of eyes caused by bacteria
- Bilateral mycobacterial keratitis
- Corneal abrasion
- Cutaneous syndrome with ichthyosis
- Factitious keratitis
- Fungal keratitis
- Infected corneal abrasion
- Infectious epithelial keratitis
- Keratitis
- Keratitis caused by infection
- Keratitis of left eye caused by bacteria
- Keratitis of left eye caused by fungus
- Keratitis of right eye caused by bacteria
- Keratitis of right eye caused by fungus
- KID syndrome
- Left mycobacterial keratitis
- Mycobacterial keratitis
- Old keratitis
- Parasitic keratitis
- Right mycobacterial keratitis
- Senter syndrome
- Superficial injury of cornea
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to H16.9: its own notes plus those printed at Chapter 7. A note printed at a category, block or chapter applies to every code under it.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- diabetes mellitus related eye conditions (E09.3-, E10.3-, E11.3-, E13.3-)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury (trauma) of eye and orbit (S05.-)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
- syphilis related eye disorders (A50.01, A50.3-, A51.43, A52.71)
Notes
General instructions on how these codes are used.
- Use an external cause code following the code for the eye condition, if applicable, to identify the cause of the eye condition
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Keratitis
inflammation of the cornea.
Patient EducationClinical
Corneal Disorders
Your cornea is the outermost layer of your eye. It is clear and shaped like a dome. The cornea helps to shield the rest of the eye from germs, dust, and other harmful matter. It also helps your eye to focus. If you wear contact lenses, they float on top of your corneas.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert H16.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About H16.9Overview
What is the ICD-10 code for unspecified keratitis?
The ICD-10-CM code for unspecified keratitis is H16.9 (sometimes written as H169). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is H16.9 (Keratitis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified keratitis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does H16.9 group to?
On inpatient claims, unspecified keratitis maps to MS-DRG 125, 124, with relative weights from 0.7699 to 1.2470 depending on complications. Higher weights mean higher Medicare reimbursement.
Can H16.9 be a principal diagnosis?
No. The Medicare Code Editor rejects this code as a principal diagnosis because unspecified keratitis describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.
What is the ICD-9 equivalent of H16.9?
Under the General Equivalence Mappings, unspecified keratitis converts to ICD-9-CM 370.9 (keratitis NOS). The mapping is a direct match.
