LogoCrystal's MCW Coder Hub

H20.012

6 min read

🧬ICD-10 CM H20.012 - Primary iridocyclitis, left eye

Short Definition

Primary iridocyclitis of the left eye — acute or subacute inflammation of the iris and ciliary body of the left eye with no identified infectious or systemic etiology at the time of coding, encompassing idiopathic and HLA-B27-associated anterior uveitis.

Long Clinical Definition

ICD-10 CM H20.012 captures primary iridocyclitis of the left eye — the most common subtype of anterior uveitis, representing inflammation of the iris (iritis) and ciliary body (cyclitis) in the left eye when no specific causative systemic or infectious condition has been identified or is being separately coded.

“Primary” in this context means the iridocyclitis is either idiopathic or associated with an underlying condition (such as HLA-B27 spondyloarthropathy) where the systemic condition is separately coded alongside. It does not mean secondary infectious or secondary noninfectious iridocyclitis (which have their own codes at H20.031-H20.042).

The inflammatory process disrupts the blood-aqueous barrier, allowing protein and white blood cells to enter the anterior chamber, producing the classic slit-lamp findings of cells and flare. Severe cases may produce hypopyon (H20.052), posterior synechiae, elevated IOP, or cataract over time.

Code Structure and Tree

  • H00-H59 Diseases of the eye and adnexa
    • H15-H22 Disorders of sclera, cornea, iris and ciliary body
      • H20 Iridocyclitis
        • H20.0 Acute and subacute iridocyclitis
          • H20.01 Primary iridocyclitis
            • H20.011 Primary iridocyclitis, right eye
            • H20.012 Primary iridocyclitis, left eye
            • H20.013 Primary iridocyclitis, bilateral
            • H20.019 Primary iridocyclitis, unspecified eye
          • H20.02x Recurrent acute iridocyclitis
          • H20.03x Secondary infectious iridocyclitis
          • H20.04x Secondary noninfectious iridocyclitis
          • H20.05x Hypopyon
        • H20.1x Chronic iridocyclitis
        • H20.2x Lens-induced iridocyclitis
        • H20.8x Other iridocyclitis
        • H20.9 Unspecified iridocyclitis

Includes / Excludes

Includes

  • Idiopathic acute anterior uveitis, left eye.
  • HLA-B27-associated acute anterior uveitis, left eye (when systemic condition not separately documented or is being coded alongside).
  • Acute iritis, left eye.
  • Acute iridocyclitis without documented infectious or systemic etiology, left eye.

Excludes1 — Do NOT Use H20.012 When These Are the Documented Cause

When iridocyclitis is explicitly documented as due to the following, use the disease-specific code from that chapter instead:

ConditionCorrect Code
Diabetes mellitusE08-E13 with .39 suffix
Herpes simplexB00.51
Herpes zosterB02.32
Syphilis (acute)A51.43
Late syphilisA52.71
Late congenital syphilisA50.39
SarcoidosisD86.83
TuberculosisA18.54
ToxoplasmosisB58.09
GonococcalA54.32
DiphtheriaA36.89

Code Also — Use Additional Code When Documented

  • Ankylosing spondylitis → M45.-
  • Psoriatic arthritis → L40.5x
  • Reactive arthritis → M02.-
  • IBD-associated → K50-K51.-
  • Behcet disease → M35.2
  • Juvenile idiopathic arthritis → M08.-

HCC / Risk Adjustment

  • H20.012 does not map to a CMS-HCC directly.
  • The underlying systemic conditions that commonly drive primary iridocyclitis do carry HCC weight and must be coded when confirmed:
    • Ankylosing spondylitis (M45.-) → HCC 40
    • IBD (K50-K51) → HCC 35
    • JIA (M08.-) → HCC 40
    • Multiple sclerosis (G35.-) → HCC 77
  • Always code the confirmed systemic disease alongside H20.012 for full clinical documentation integrity and appropriate RAF capture.

MS-DRG Considerations

  • H20.012 falls under MDC 02 - Diseases and Disorders of the Eye.
  • Inpatient admission for isolated primary iridocyclitis is uncommon — most cases are managed outpatient.
  • When inpatient admission is required (e.g., severe bilateral disease, hypopyon unresponsive to outpatient therapy, systemic disease driving admission):
    • DRG 124 - Other disorders of the eye with MCC.
    • DRG 125 - Other disorders of the eye without MCC.
  • When the systemic disease (e.g., ankylosing spondylitis flare, IBD) drives the admission, that condition determines the MDC and DRG — H20.012 becomes a secondary diagnosis.

wRVU and CPT Pairings

wRVUs apply to CPT codes, not ICD-10-CM. Common pairings for H20.012:

Eye Exam / Office Visit

CPTDescription
92002New patient, intermediate ophthalmological exam
92004New patient, comprehensive ophthalmological exam
92012Established patient, intermediate ophthalmological exam
92014Established patient, comprehensive ophthalmological exam
99214-99215Established patient office E/M — if E/M coding used

Diagnostic Testing

CPTDescription
92250Fundus photography with interpretation
92132Anterior segment OCT
92020Gonioscopy— if angle evaluation needed

Procedures (if applicable)

CPTDescription
68200Subconjunctival injection — periocular steroid
67028Intravitreal injection — intravitreal triamcinolone for refractory uveitis

Assistant at Surgery

Not applicable at the diagnosis-code level. If surgical intervention is required (e.g., anterior chamber tap — CPT 65800), check the MPFS assistant-at-surgery indicator for the specific CPT. Anterior chamber tap is a single-surgeon procedure; assistant billing is not typically warranted.

Clinical Features

Symptoms:

  • Unilateral (left) red eye, acute pain, photophobia, blurred vision, tearing.
  • Often sudden in onset, particularly in HLA-B27-associated cases.

Slit-lamp findings:

  • Circumlimbal (ciliary) injection.
  • Anterior chamber cells and flare (graded 0-4+).
  • Keratic precipitates (KPs) on corneal endothelium.
  • Posterior synechiae in recurrent or undertreated disease.
  • Hypopyon in severe cases → code H20.052 additionally.
  • IOP elevated (trabecular inflammation) or low (ciliary body suppression).

Common underlying associations:

  • HLA-B27 spondyloarthropathy (ankylosing spondylitis, psoriatic arthritis, reactive arthritis, IBD).
  • Idiopathic (no systemic cause found despite workup).

Documentation Best Practices

  • Specify laterality — left, right, or bilateral. Avoid unspecified (H20.019).
  • State onset type — acute vs. recurrent vs. chronic — to ensure correct sub-category selection.
  • Document anterior chamber grade (cells and flare) for severity tracking.
  • Document underlying systemic condition if confirmed — and code it.
  • If hypopyon is present, add H20.052 and document its height in mm.
  • Document IOP for both eyes and any IOP-lowering treatment.
  • Note prior episodes — if recurrent, H20.022 (recurrent acute iridocyclitis, left eye) may be more appropriate than H20.012.

Coding Guideline Highlights

  • Use H20.012 when the iridocyclitis is primary — no separate infectious agent or Excludes1 systemic condition is the documented cause.
  • If the iridocyclitis is recurrent (episodes with disease-free intervals of 3+ months off treatment), use H20.022 instead.
  • If the episode is chronic (persistent 3+ months), use H20.12 instead.
  • Never use H20.012 when an Excludes1 condition (herpes, sarcoidosis, TB, syphilis, etc.) is the documented etiology — those redirect to disease-specific codes.

Coding Examples

Example 1 — New Patient, Acute Idiopathic Iridocyclitis, Left Eye

Scenario 30-year-old new patient with 2-day history of left eye pain, photophobia, and redness. Slit-lamp shows 2+ cell, 1+ flare, no hypopyon. Workup initiated. No systemic diagnosis established yet. Started on topical prednisolone and cyclopentolate.

ICD-10-CM

  • H20.012 - Primary iridocyclitis, left eye.

CPT

  • 92004 - New patient, comprehensive ophthalmological exam.

Example 2 — Established Patient with HLA-B27 Positive Ankylosing Spondylitis

Scenario 42-year-old with known ankylosing spondylitis presents with acute left eye flare. Slit-lamp confirms anterior chamber cells and flare. Intensified topical steroids prescribed.

ICD-10-CM

  • H20.012 - Primary iridocyclitis, left eye.
  • M45.9 - Ankylosing spondylitis, unspecified sites in spine.

CPT

  • 92014 - Established patient, comprehensive ophthalmological exam.

Example 3 — Recurrent Episode, Left Eye (Code Selection Note)

Scenario Same patient returns 8 months later with another acute flare of the left eye, having been symptom-free and off treatment between episodes.

ICD-10-CM

  • H20.022 - Recurrent acute iridocyclitis, left eye (use this — not H20.012 — when the pattern is clearly recurrent with documented disease-free intervals).
  • M45.9 - Ankylosing spondylitis.

Example 4 — Severe Iridocyclitis with Hypopyon

Scenario Established patient presents with severe left eye pain and visual blur. Slit-lamp shows 3+ cell, 2+ flare, and 1.5 mm hypopyon in the inferior anterior chamber.

ICD-10-CM

  • H20.052 - Hypopyon, left eye (primary — hypopyon indicates the most severe level of this inflammatory episode).
  • H20.012 - Primary iridocyclitis, left eye (context code).

CPT

  • 92014 - Established patient, comprehensive ophthalmological exam.

Graph View

Recent Notes