2027 ICD-10-CM Diagnosis Code H16.329Diffuse interstitial keratitis, unspecified eye
ICD-10-CM Codes›H00–H59›H15-H22›H16
- Billable — Valid for Submission
- Chronic Condition
H16.329 is a billable ICD-10-CM diagnosis code for diffuse interstitial keratitis, unspecified eye. 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. Coders also document this condition as Cogan's syndrome. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cornea and external disease.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Cogan's syndrome
- Diffuse interstitial keratitis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to H16.329: 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.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Cogan Syndrome
a condition consisting of inflammatory eye disease usually presenting as interstitial keratitis, vestibuloauditory dysfunction, and large- to medium-vessel vasculitis.
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 H16.329 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About H16.329Overview
What is the ICD-10 code for diffuse interstitial keratitis, unspecified eye?
The ICD-10-CM code for diffuse interstitial keratitis, unspecified eye is H16.329 (sometimes written as H16329). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is H16.329 (Diffuse interstitial keratitis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report diffuse interstitial keratitis, unspecified eye on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does H16.329 group to?
When diffuse interstitial keratitis, unspecified eye is the principal diagnosis on an inpatient stay, it groups to MS-DRG 125, 124, with relative weights from 0.7699 to 1.2470 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of H16.329?
Under the General Equivalence Mappings, diffuse interstitial keratitis, unspecified eye converts to ICD-9-CM 370.52 (diffus interstit keratit). The mapping is approximate, so confirm the match fits the documentation.
