2026 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 2026 (October 1, 2025 through September 30, 2026) 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
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Keratitis(nodular) (nonulcerative) (simple) (zonular)
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Acanthamoeba Keratitis
infection of the cornea by an ameboid protozoan which may cause corneal ulceration leading to blindness.Corneal Ulcer
loss of epithelial tissue from the surface of the cornea due to progressive erosion and necrosis of the tissue; usually caused by bacterial, fungal, or viral infection.Keratitis
inflammation of the cornea.Keratitis, Dendritic
a form of herpetic keratitis characterized by the formation of small vesicles which break down and coalesce to form recurring dendritic ulcers, characteristically irregular, linear, branching, and ending in knoblike extremities. (dictionary of visual science, 3d ed)Keratitis, Herpetic
a superficial, epithelial herpesvirus hominis infection of the cornea, characterized by the presence of small vesicles which may break down and coalesce to form dendritic ulcers (keratitis, dendritic). (dictionary of visual science, 3d ed)Grade 3 Keratitis, CTCAE|CTCAE Grade 3 Keratitis (corneal inflammation/corneal ulceration)|Grade 3 Keratitis|Grade 3 Keratitis (corneal inflammation/corneal ulceration)
symptomatic with marked decrease in visual acuity (best corrected visual acuity worse than 20/40 or more than 3 lines of decreased vision from known baseline, up to 20/200); corneal ulcer; limiting self-care adl or severe impact on age-appropriate normal daily activity (pediatric)Photokeratitis|Arc Welder's Eye|Arc eye|Ultraviolet Keratitis|Ultraviolet Keratitis|Welder's Flash
injury to the cornea secondary to ultraviolet light.Stromal Keratitis|Stromal keratitis
a corneal inflammation affecting the stromal layer.Acanthamoeba Keratitis
keratitis due to infection by acanthamoeba; it is usually associated with soft contact lens wear, particularly overnight wear.Dendritic Keratitis
infection of the cornea with herpes simplex virus, resulting in branching ulcers of the corneal tissue.Fungal Keratitis
keratitis caused by fungi.Grade 1 Keratitis, CTCAE|CTCAE Grade 1 Keratitis (corneal inflammation/corneal ulceration)|Grade 1 Keratitis|Grade 1 Keratitis (corneal inflammation/corneal ulceration)
asymptomatic; clinical or diagnostic observations only; intervention not indicatedGrade 2 Keratitis, CTCAE|CTCAE Grade 2 Keratitis (corneal inflammation/corneal ulceration)|Grade 2 Keratitis|Grade 2 Keratitis (corneal inflammation/corneal ulceration)
symptomatic; moderate decrease in visual acuity (best corrected visual acuity 20/40 and better or 3 lines or less decreased vision from known baseline)Grade 3 Keratitis, CTCAE|CTCAE Grade 3 Keratitis (corneal inflammation/corneal ulceration)|Grade 3 Keratitis|Grade 3 Keratitis (corneal inflammation/corneal ulceration)
symptomatic with marked decrease in visual acuity (best corrected visual acuity worse than 20/40 or more than 3 lines of decreased vision from known baseline, up to 20/200); corneal ulcer; limiting self care adlGrade 4 Keratitis, CTCAE|CTCAE Grade 4 Keratitis (corneal inflammation/corneal ulceration)|Grade 4 Keratitis|Grade 4 Keratitis (corneal inflammation/corneal ulceration)
perforation; best corrected visual acuity of 20/200 or worse in the affected eyeInfectious Keratitis|Infective Keratitis
inflammation of the cornea secondary to an infectious process.Keratitis, CTCAE|Keratitis|Keratitis|Keratitis (corneal inflammation/corneal ulceration)
a disorder characterized by inflammation to the cornea of the eye.PAX6 wt Allele|AN|AN2|Aniridia, Keratitis Gene|D11S812E|MGC17209|MGDA|Paired Box 6 wt Allele|Paired Box Gene 6 (Aniridia, Keratitis) Gene|WAGR
human pax6 wild-type allele is located in the vicinity of 11p13 and is approximately 29 kb in length. this allele, which encodes paired box protein pax-6, plays a role in the mediation of transcription. mutations in the gene are associated with a number of congenital disorders of the eye.Photokeratitis|Ultraviolet Keratitis|Ultraviolet Keratitis
injury to the cornea secondary to ultraviolet light.Superficial Injury of Cornea
trauma to the corneal epithelium.Corneal Abrasion
injury to the epithelium 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.
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Convert H16.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About H16.9Overview
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, 2025 through September 30, 2026.
What MS-DRG does H16.9 group to?
On inpatient claims, unspecified keratitis maps to MS-DRG 124, 125, with relative weights from 0.7678 to 1.3231 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.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
