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H57.04

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🧬 ICD-10 CM H57.04 — Mydriasis

Billable Code Confirmed

[ICD-10-CM] H57.04 is a valid, billable 5-character ICD-10-CM diagnosis code for FY2026. The character structure is: H (eye chapter) + 57 (other disorders of eye and adnexa) + .0 (anomalies of pupillary function) + 4 (mydriasis). No additional characters are required — the code is complete at 5 characters.

Non-Billable Parent Codes — Never Submit These

  • ❌ H57 — 3-character header — does not specify which disorder of the eye and adnexa
  • ❌ H57.0 — 4-character header — does not specify which pupillary anomaly

Always submit H57.04 (all 5 characters) when pathological or persistent pupil dilation is documented without a more specific etiology-linked code available.

Clinical Context: Sign vs. Diagnosis

ICD-10-CM H57.04 captures mydriasis as a standalone pupillary finding — most often when the underlying cause has not yet been established or when it is the primary manifestation under evaluation. When the etiology is known and a more specific code exists (e.g., H49.00 — Third (oculomotor) nerve palsy, unspecified eye), that specific code should take precedence. H57.04 is most appropriately used when mydriasis itself is the focus of the encounter or when it represents an isolated, undifferentiated finding.

Code Classification

ICD-10-CM Diagnosis Code — wRVU, assistant payable, and global period fields are not applicable to diagnosis codes. For associated procedural coding, see the CPT Procedural Crosswalk and ICD-10-PCS Crosswalk sections below.

🔍 Code Description

ICD-10 CM H57.04 classifies mydriasis — abnormal, pathological dilation of the pupil, typically defined as a pupil diameter exceeding 6 mm combined with failure to constrict appropriately when stimulated with light.1,2 It exists as a distinct code because mydriasis represents a clinically significant pupillary anomaly that can be the first sign of life-threatening intracranial pathology, a manifestation of autonomic dysfunction, or an isolated ophthalmological finding requiring workup.

Pupil size is governed by the balance between the parasympathetic pupilloconstrictor pathway (originating at the Edinger-Westphal nucleus and traveling with CN III to the iris sphincter) and the sympathetic pupillodilator pathway.3 Mydriasis results from failure of parasympathetic constriction — due to CN III compression, pharmacologic blockade, trauma, or autonomic neuropathy — or from unopposed sympathetic tone. Clinically, it may present as a unilateral “blown” pupil in the context of uncal herniation or as a bilateral finding in severe drug toxicity or metabolic coma.

🌳 Code Tree / Hierarchy

H57 Other disorders of eye and adnexa ❌ Non-billable
│
├── H57.0 Anomalies of pupillary function ❌ Non-billable
│     │
│     ├── H57.00 Unspecified anomaly of pupillary function ✅ Billable
│     ├── H57.01 Argyll Robertson pupil, atypical ✅ Billable
│     ├── H57.02 Anisocoria ✅ Billable
│     ├── H57.03 Miosis ✅ Billable
│     ├── H57.04 Mydriasis ◀ THIS CODE ✅ Billable
│     ├── H57.05 Tonic pupil ❌ Non-billable
│     │     ├── H57.051 Tonic pupil, right eye ✅ Billable
│     │     ├── H57.052 Tonic pupil, left eye ✅ Billable
│     │     ├── H57.053 Tonic pupil, bilateral ✅ Billable
│     │     └── H57.059 Tonic pupil, unspecified eye ✅ Billable
│     └── H57.09 Other anomalies of pupillary function ✅ Billable
│
├── H57.1 Ocular pain ❌ Non-billable
├── H57.8 Other specified disorders of eye and adnexa ❌ Non-billable
└── H57.9 Unspecified disorder of eye and adnexa ✅ Billable

Tip

Mydriasis vs. Tonic Pupil (Adie Syndrome) Adie’s tonic pupil — a parasympathetic denervation condition characterized by slow, tonic light response — maps to H57.051-H57.059, not H57.04. If the provider specifically documents tonic pupil or Adie syndrome, select the laterality-specific H57.05x series. H57.04 is reserved for mydriasis without that specific characterization.

✅ Includes

The following clinical terms and scenarios map to H57.04 when documented:

  • Dilated pupil (pathological or persistent, not pharmacologically induced for exam)
  • Blown pupil (traumatic or compressive context)
  • Mydriasis not due to mydriatic agents
  • Congenital mydriasis
  • Episodic mydriasis (without further specification)
  • Fixed pupil dilation documented as a clinical finding under evaluation

❌ Excludes

Excludes 1 — Cannot Be Coded Simultaneously with H57.04

CodeDescriptionNote
No Excludes 1 annotations exist for H57.04—No mutually exclusive codes defined in the tabular

Excludes 1 Violation Risk

While no formal Excludes 1 notes are attached to H57.04, avoid coding it simultaneously with H57.05x (Tonic pupil) — clinically, a tonic Adie pupil and generic mydriasis are overlapping descriptions of the same pupil. Code the most specific finding documented.

Excludes 2 — May Be Coded in Addition if Separately Present

CodeDescriptionNote
No Excludes 2 annotations exist for H57.04—Code the underlying etiology and any additional manifestations separately per coding guidelines

📋 Clinical Overview

Etiology-Based Distinction — Why Mydriasis Occurs

Accurately coding mydriasis requires understanding whether the etiology is known — because a known cause often has its own, more specific code. The table below distinguishes major etiologic categories that produce mydriasis and their coding implications.

FeatureH57.04 — Isolated/Undifferentiated MydriasisCN III Palsy (H49.00-H49.03)Pharmacologic/Drug-Induced
MechanismParasympathetic failure or sympathetic excess, cause not fully establishedCN III compression (aneurysm, herniation, trauma) disrupts pupilloconstrictor fibersAnticholinergics, sympathomimetics, tropicamide instilled for exam
LateralityNo laterality axis in H57.04Code specifies right, left, bilateral, or unspecifiedTypically bilateral; transient
Pupillary light reflexAbsent or sluggishAbsent (efferent defect)Absent (pharmacologic blockade)
Associated findingsVaries; may be isolatedPtosis, ophthalmoplegia (“down and out”), diplopiaNone — resolves within hours
When to use this codeMydriasis is the documented finding under workup; etiology not yet establishedUse CN III palsy code if documented; do NOT also code H57.04Do NOT code H57.04 — pharmacologic dilation for examination is not a reportable diagnosis
Inpatient frequencyCommon as admitting sign in neuro/traumaHigh — CN III palsy is a critical finding in intracranial emergenciesNot coded

CDI Query Trigger — Etiology of Documented Mydriasis

When an inpatient record documents a “dilated” or “non-reactive” pupil without specifying the cause, query the physician: Is this mydriasis due to CN III palsy, pharmacologic dilation for examination, traumatic iridoplegia, or an autonomic neuropathy? The response may allow assignment of a more specific, higher-weighted code and better reflects clinical complexity.

Associated Manifestations / Common Inpatient Presentations

Mydriasis in the inpatient setting frequently occurs as a sign of the following conditions — each with its own ICD-10-CM code that should be sequenced as the principal or primary diagnosis when established:

  • CN III (Oculomotor) Nerve Palsy: Ptosis, ophthalmoplegia, diplopia, and ipsilateral mydriasis — the classic triad; caused by intracranial aneurysm (PComA), uncal herniation, or microvascular ischemia3,4
  • Traumatic Brain Injury / Uncal Herniation: Unilateral blown pupil is a critical neurological emergency sign; code the TBI as principal with herniation3
  • Adie (Holmes-Adie) Syndrome: Tonic pupil with light-near dissociation and absent deep tendon reflexes — code H57.05x with laterality, not H57.042
  • Acute Angle-Closure Glaucoma: Mydriasis is a precipitating feature — code the glaucoma as principal1,2
  • Drug Intoxication / Anticholinergic Toxidrome: Bilateral mydriasis with tachycardia, dry skin, hyperthermia — code the poisoning or adverse effect as principal

Coding Manifestations

Always code the established underlying etiology as principal when known. Examples of codes that should precede or replace H57.04:

  • H49.00 — Third (oculomotor) nerve palsy, unspecified eye
  • S06.30XA — Unspecified focal traumatic brain injury (initial encounter)
  • H40.211 — Acute angle-closure glaucoma, right eye (example)

💰 HCC Risk Adjustment (CMS-HCC v28)

FieldDetail
CMS-HCC Model Versionv28 (2024-2026 Implementation)
HCC Assignment❌ Not HCC-Mapped
HCC CategoryN/A
RAF CoefficientN/A

H57.04 does not map to any HCC category under CMS-HCC v28. It is a symptomatic/sign-level code that does not independently drive risk-adjusted resource forecasting.

Capture the Underlying Condition for RAF

While H57.04 itself carries no HCC weight, the etiology behind mydriasis often does. For example, a CN III palsy from diabetic neuropathy may tie back to an HCC-mapped diabetes complication code. Ensure the underlying condition is fully documented and coded to capture appropriate RAF impact.

🏥 MS-DRG Assignment

MDC 02 — Diseases and Disorders of the Eye

DRGTitleEst. Relative Weight*
DRG 123Neurological Eye Disorders~0.75

DRG 123 is a single flat-rate DRG — there is no MCC or CC split. Approximate weight ~0.7542 based on FY2025 data; verify against IPPS FY2026 Final Rule Table 5.

Sequencing and DRG Impact

When H57.04 is sequenced as principal diagnosis, the case groups to DRG 123 (Neurological Eye Disorders) with a modest relative weight. Because DRG 123 has no CC/MCC split, secondary diagnoses that would typically drive DRG weight higher have no effect here. If the underlying etiology is identified during the admission (e.g., CN III palsy confirmed by MRI), re-sequencing to the more specific condition may change the MDC assignment. For example, if CN III palsy is confirmed as a manifestation of an intracranial aneurysm, the encounter may group under MDC 01 instead, with significantly different DRG implications.

🔗 Related ICD-10-CM Codes

Pupillary Anomaly Siblings (H57.0x Family)

CodeDescription
H57.04Mydriasis ← This Code
H57.00Unspecified anomaly of pupillary function
H57.01Argyll Robertson pupil, atypical
H57.02Anisocoria
H57.03Miosis
H57.051Tonic pupil, right eye (Adie syndrome)
H57.052Tonic pupil, left eye
H57.053Tonic pupil, bilateral
H57.059Tonic pupil, unspecified eye
H57.09Other anomalies of pupillary function

Common Etiologic Codes Driving Mydriasis (Code These Instead When Established)

CodeDescription
H49.00Third (oculomotor) nerve palsy, unspecified eye
H49.01Third (oculomotor) nerve palsy, right eye
H49.02Third (oculomotor) nerve palsy, left eye
H49.03Third (oculomotor) nerve palsy, bilateral
G51.0Bell’s palsy (for context — facial nerve, not oculomotor)
H40.211Acute angle-closure glaucoma, right eye (example)

🛠️ Commonly Associated CPT Codes (Ophthalmology)

Inpatient and Outpatient Profee Setting

The following CPT codes are typically associated with the evaluation of mydriasis in the ophthalmology or neurology profee setting. In the inpatient facility setting, these are profee charges only; the facility bills the DRG. Note that pharmacological dilation (mydriasis induced for exam) is bundled into the ophthalmologic evaluation codes and is not separately reportable.5,6

CPT CodeDescriptionProfee Coding Notes (Modifier 26)
92014Ophthalmological services: established patient, comprehensiveUse when all 12 exam elements performed; mydriasis for ophthalmoscopy is bundled — do not separately bill the dilation
92004Ophthalmological services: new patient, comprehensiveSame bundling rules as 92014; mydriasis for exam is included
92012Ophthalmological services: established patient, intermediateFor evaluation of new diagnostic problem; mydriasis bundled
92250Fundus photography with interpretation and reportSeparately billable when performed; Modifier 26 for professional component in facility; Modifier 50 NOT applicable — bilateral is standard
92201Ophthalmoscopy, extended, with retinal drawing; with panretinal examinationSeparately billable extended service; Modifier 26 in facility

NCCI Bundling Considerations

  • Mydriasis (pharmacologic dilation for examination) is not separately reportable — it is bundled into 92002, 92004, 92012, and 92014. Billing a separate charge for the mydriatic drops or the dilation as a standalone service would constitute unbundling.
  • 92250 (Fundus photography) may be billed on the same date as an E/M or ophthalmologic exam if separately documented with medical necessity; no modifier is required to unbundle these services as they represent distinct procedures.

🔬 ICD-10-PCS Crosswalk (Inpatient Procedures)

When H57.04 is an inpatient diagnosis, there are no PCS codes that directly address mydriasis itself. PCS codes in this context apply to the underlying condition requiring surgical or procedural intervention.

PCS SectionBody SystemRoot OperationClinical Application
B (Imaging)8 (Eye)3 (MRI)Neuroimaging to evaluate for intracranial aneurysm or CN III compressive lesion causing mydriasis — e.g., brain MRI/MRA
B (Imaging)8 (Eye)1 (Fluoroscopy)Cerebral angiography when PComA aneurysm is suspected as cause of pupil-involving CN III palsy
0 (Medical and Surgical)8 (Eye)0 (Alteration)Iris procedures (e.g., iridoplasty or pupilloplasty in cases of traumatic mydriasis failing to resolve)

💊 Coding Scenarios and Examples

Scenario 1 — Inpatient: New Mydriasis as Admitting Sign — Etiology Confirmed During Stay

Clinical Vignette: A 58-year-old woman presents to the ED with sudden onset of severe headache, ptosis of the right eyelid, and a right pupil measuring 7 mm and non-reactive to light. MRI/MRA confirms a right posterior communicating artery aneurysm with CN III compression. Neurosurgery is consulted; the patient is admitted and undergoes endovascular coiling during the inpatient stay.

Principal Diagnosis:

  • H49.01 — Third (oculomotor) nerve palsy, right eye (confirmed etiology of mydriasis; H57.04 is NOT separately coded — the palsy encompasses the pupillary finding)

Secondary Diagnoses:

  • Q28.3 — Other malformations of cerebral vessels (or the appropriate intracranial aneurysm code)
  • R51.9 — Headache, unspecified (if not better explained by the aneurysm code)

MS-DRG Assignment: Routes to MDC 01 based on CN III palsy and intracranial procedure — significantly higher DRG weight than DRG 123.

Scenario 2 — Inpatient: Undifferentiated Mydriasis, Workup Inconclusive

Clinical Vignette: A 34-year-old male is admitted for evaluation of a left pupil fixed at 6.5 mm with sluggish light response, first noted three days prior. No headache, no trauma, no ocular medications. Neuroimaging including MRI brain and MRA of the Circle of Willis is negative. Pharmacologic testing is equivocal. Provider documents “mydriasis, etiology unclear” at discharge.

Principal Diagnosis:

  • H57.04 — Mydriasis (most specific available code when etiology remains undetermined at discharge)

Secondary Diagnoses:

  • No CC/MCC identified — groups to DRG 123, flat rate

MS-DRG Assignment: DRG 123 — Neurological Eye Disorders (~0.75 RW). No CC/MCC split exists for this DRG.

Scenario 3 — CDI Query: “Dilated Pupil” Documented Without Etiology Specification

Clinical Vignette: A 67-year-old male is admitted following a motor vehicle accident with documented traumatic brain injury. The nursing assessment notes “left pupil dilated and sluggish.” The attending’s discharge summary lists “altered mental status, TBI” but does not specifically address the pupil finding or link it to the injury or to a specific nerve palsy.

Action / Outcome: The coder cannot determine whether the dilated pupil represents pharmacologic dilation from an administered medication (not reportable), a traumatic CN III palsy (more specific code available), or incidental mydriasis. A CDI query is required before assigning H57.04 or any more specific code.

Query Response: Provider updates documentation to confirm: “Left pupil dilation is consistent with traumatic oculomotor nerve injury from the TBI — this represents a CN III palsy secondary to the head trauma.”

Corrected ICD-10-CM Coding:

  • H49.02 — Third (oculomotor) nerve palsy, left eye (replaces H57.04 — etiology now established)
  • S06.9X1A — Unspecified intracranial injury with loss of consciousness — 30 minutes or less, initial encounter (or the most specific TBI code supported)

⚠️ Coding Pitfalls and Tips

Pitfall or Tip
❌Coding H57.04 when the etiology is known. If CN III palsy, Adie syndrome, or acute glaucoma is documented, use the specific code — not the generic mydriasis code. H57.04 should never be assigned when a more specific etiology-linked code is available.
❌Reporting H57.04 for pharmacologic dilation during exam. Tropicamide or other mydriatic drops instilled for ophthalmoscopy do not create a reportable diagnosis. H57.04 is for pathological mydriasis, not a procedure-induced transient finding.
❌Expecting a CC/MCC split for DRG 123. DRG 123 is a flat-rate DRG. Stacking secondary diagnoses will not drive the case to a higher DRG within MDC 02’s Neurological Eye Disorders grouping.
✅Query when documentation says “dilated pupil” without cause. A one-line nursing note is insufficient to assign H57.04 — confirm whether the finding is pharmacologic, traumatic, or pathological via CDI query before coding.
✅Re-sequence when etiology is established. If the admission begins with undifferentiated mydriasis (H57.04) but the workup confirms CN III palsy or intracranial pathology, revise the principal diagnosis to the confirmed condition — this can significantly shift MDC and DRG assignment.
✅Code all contributing conditions separately. Even when H57.04 is appropriate as principal, fully code comorbidities that may have caused or contributed to the mydriasis (e.g., diabetes, hypertension, atherosclerosis in the context of microvascular CN III palsy) to capture clinical complexity.

📚 Sources

  1. CMS/NCHS. ICD-10-CM Official Guidelines for Coding and Reporting, FY2026. Section I.C.7 — Diseases of the Eye and Adnexa.
  2. CMS. ICD-10-CM Tabular List of Diseases and Injuries, FY2026. Code H57.04 — Mydriasis; H57.05 — Tonic pupil. National Center for Health Statistics.
  3. Prasad S, Volpe NJ. “Paralytic strabismus: third, fourth, and sixth nerve palsy.” Neurologic Clinics. 2010;28(3):789-816. (Source for CN III anatomy and causes of mydriasis.)
  4. StatPearls. “Cranial Nerve III Palsy (Oculomotor Palsy).” NCBI Bookshelf. Updated February 2026. (Source for differential diagnosis and clinical presentation of oculomotor palsy with mydriasis.)
  5. CMS. Medicare Coverage Database — Article A57071: Billing and Coding: Ophthalmology: Posterior Segment Imaging (Extended Ophthalmoscopy and Fundus Photography). (Source for CPT 92250, 92201, 92227-92228 bundling and modifier guidance.)
  6. American Academy of Ophthalmology. Fact Sheet for Comprehensive Eye Visit Codes: 92004 and 92014. Updated 2024. (Source for mydriasis bundling within ophthalmologic exam codes.)
  7. CMS. IPPS Final Rule FY2026 — MS-DRG Definitions Manual v43.0/v43.1. MDC 02 logic tables — DRG 123 Neurological Eye Disorders.
  8. CMS. 2026 Medicare Advantage Risk Adjustment — CMS-HCC Model v28 ICD-10-CM Mappings. (Confirmation of H57.04 non-HCC-mapped status.)

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