G45.3

G45.3 - Amaurosis Fugax

Code Classification

• ICD-10-CM Code: G45.3
• Short Description: Amaurosis fugax
• Long Description: Amaurosis fugax
• Chapter: G (G00-G99) - Diseases of the nervous system
• Block: G40-G47 - Episodic and paroxysmal disorders
• Category: G45 - Transient cerebral ischemic attacks and related syndromes

Clinical Description

Amaurosis fugax is a transient monocular vision loss (TMVL) characterized by a sudden, temporary loss of vision in one eye. The term derives from Latin meaning “fleeting blindness.” This condition is typically caused by temporary retinal ischemia due to reduced blood flow to the eye, most commonly from emboli originating from carotid artery atherosclerotic plaques.

Pathophysiology

The condition results from transient retinal or optic nerve hypoperfusion, most often due to:

• Embolic phenomenon from carotid artery stenosis or ulcerated plaques
• Thrombotic occlusion of the ophthalmic or central retinal artery
• Hemodynamic insufficiency from severecarotid stenosis
• Giant cell arteritis (temporal arteritis) in older patients
• Hypercoagulable states
• Cardiac emboli

Clinical Presentation

• Onset: Sudden, painless vision loss
• Duration: Typically lasts seconds to minutes (usually <5 minutes), rarely up to 24 hours
• Pattern: Often described as a “curtain” or “shade” descending over the visual field
• Recovery: Complete return to normal vision
• Laterality: Monocular (affecting one eye only)
• Associated symptoms: May have no other symptoms or may be accompanied by other TIA symptoms

Significance

Amaurosis fugax is considered a retinal TIA and is a critical warning sign of:

• High risk for stroke (10-15% risk within 90 days if untreated)
• Significant carotid artery disease (50-70% have ipsilateral carotid stenosis)
• Cardiovascular disease
• Need for urgent neurovascular evaluation

HCC Information

HCC Category: HCC 100 - Transient Ischemic Attack

• Risk Adjustment Factor (RAF): Community: 0.301 | Institutional: 0.228
• CMS-HCC Model: Maps to HCC 100 in the CMS-HCC V24 and V28 models
• Payment Impact: This diagnosis contributes to risk adjustment calculations for Medicare Advantage plans
• Documentation Requirements:
  • Must be physician-documented
  • Requires active treatment or monitoring
  • Should document the date of occurrence
  • Should describe the clinical presentation and duration

Important HCC Coding Notes:

• Code only when the condition is being actively addressed during the encounter
• Does not capture if patient had amaurosis fugax years ago without current manifestation
• Requires physician (not nurse/PA alone) documentation for risk adjustment
• Should be supported by appropriate diagnostic workup (carotid ultrasound, echocardiogram, etc.)

wRVU / Assistant Surgeon Information

Note: wRVU (work Relative Value Units) and assistant surgeon payability apply to CPT procedure codes, not ICD-10 diagnosis codes. This is a diagnosis code used for reporting the patient’s condition, not a procedural code for billing services rendered.

For procedures related to amaurosis fugax treatment or diagnosis, refer to appropriate CPT codes such as:

• 93880-93882 (Duplex scan of extracranial arteries)
• 35301 (Thromboendarterectomy, carotid)
• 37215-37217 (Carotid stenting)

Code Tree Hierarchy

G00-G99: Diseases of the Nervous System
└── G40-G47: Episodic and Paroxysmal Disorders
    └── G45: Transient cerebral ischemic attacks and related syndromes
        ├── G45.0: Vertebro-basilar artery syndrome
        ├── G45.1: Carotid artery syndrome (hemispheric)
        ├── G45.2: Multiple and bilateral precerebral artery syndromes
        ├── G45.3: Amaurosis fugax ◄ THIS CODE
        ├── G45.4: Transient global amnesia
        ├── G45.8: Other transient cerebral ischemic attacks and related syndromes
        └── G45.9: Transient cerebral ischemic attack, unspecified

Includes

The code G45.3 specifically includes:

• Transient monocular blindness
• Transient monocular vision loss
• Transient retinal ischemia
• Fleeting blindness
• Retinal TIA
• Transient visual loss in one eye due to vascular insufficiency

Excludes

Excludes1 (NOT CODED TOGETHER - mutually exclusive)

• Z86.73: Personal history of transient ischemic attack (TIA) and cerebral infarction without residual deficits
  • Use this code for history of resolved amaurosis fugax when no longer having episodes

Excludes2 (CAN BE CODED TOGETHER if both present)

• I63.-: Cerebral infarction (stroke)
  • Use if amaurosis fugax progresses to completed stroke
• S06.-: Traumatic intracranial hemorrhage
• I69.-: Sequelae of cerebrovascular disease

Additional Related Exclusions

• H34.0-H34.9: Retinal vascular occlusions (if there is permanent retinal artery occlusion rather than transient ischemia)
• H53.1-: Subjective visual disturbances (if symptoms are not vascular in nature)

MS-DRG Grouping

G45.3 may contribute to the following MS-DRG assignments depending on complications, comorbidities, and procedures:

Primary MS-DRG Assignment

• MS-DRG 069: Transient Ischemia without Thrombolytic

  • Geometric Mean LOS: 2.3 days
  • Relative Weight: 0.7866 (FY2025)
  • Description: For patients admitted with TIA who do not receive thrombolytic therapy

• MS-DRG 070: Nonspecific Cerebrovascular Disorders with MCC

  • Geometric Mean LOS: 4.4 days
  • Relative Weight: 1.3733
  • Description: When patient has major complications or comorbidities

• MS-DRG 071: Nonspecific Cerebrovascular Disorders with CC

  • Geometric Mean LOS: 3.0 days
  • Relative Weight: 0.9238
  • Description: When patient has complications or comorbidities

• MS-DRG 072: Nonspecific Cerebrovascular Disorders without CC/MCC

  • Geometric Mean LOS: 2.2 days
  • Relative Weight: 0.6748
  • Description: No significant complications or comorbidities

Procedure-Related DRGs

If patient undergoes carotid intervention:

• MS-DRG 033-035: Carotid artery stent procedures
• MS-DRG 036-037: Carotid artery endarterectomy

Coding Guidelines

ICD-10-CM Official Guidelines

1. Timing: Code the condition as it exists during the encounter
2. Laterality: While G45.3 does not specify laterality, document which eye was affected in clinical documentation
3. Sequencing:
   • May be principal diagnosis for admission primarily to rule out stroke
   • May be secondary diagnosis when admitted for related cardiovascular workup
4. Chronic vs Acute: Code only active episodes, not remote history

Documentation Requirements

For compliant coding, physician documentation should include:

• Specific terminology: “amaurosis fugax” or “transient monocular vision loss”
• Eye affected (right/left)
• Duration of episode
• Description of visual symptoms
• Associated symptoms (if any)
• Presumed etiology
• Workup planned or completed

Query Opportunities

Query physician when documentation states:

• “Vision loss” without specifying transient nature or duration
• “TIA” with vision changes but not clearly monocular
• “Temporary blindness” without clarifying unilateral vs bilateral
• “Visual disturbance” without vascular etiology established

Coding Examples

Example 1: Uncomplicated Admission

Scenario: 68-year-old male presents to ED with episode of sudden vision loss in right eye lasting 3 minutes, now resolved. Carotid ultrasound shows 70% right internal carotid stenosis.

Coding:

• Principal Diagnosis: G45.3 (Amaurosis fugax)
• Secondary Diagnoses:
  • I65.21 (Occlusion and stenosis of right carotid artery)
  • I10 (Essential hypertension) - if applicable
  • E78.5 (Hyperlipidemia) - if applicable
• MS-DRG: 069 (Transient Ischemia)

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Example 2: With Major Complications

Scenario: 75-year-old female with episode of amaurosis fugax left eye. Hospital course complicated by atrial fibrillation with RVR requiring cardioversion. Past medical history of CHF.

Coding:

• Principal Diagnosis: G45.3 (Amaurosis fugax)
• Secondary Diagnoses:
  • I48.91 (Atrial fibrillation, unspecified) - MCC
  • I50.9 (Heart failure, unspecified)
  • I65.22 (Occlusion and stenosis of left carotid artery) - if found
• Procedures: 5A2204Z (Cardioversion)
• MS-DRG: 070 (Nonspecific Cerebrovascular Disorders with MCC)

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Example 3: Outpatient/Observation

Scenario: 62-year-old presents with 5-minute episode of vision loss right eye 2 hours ago. Observed overnight, carotid ultrasound and echocardiogram performed, started on antiplatelet therapy, discharged.

Coding:

• First-Listed Diagnosis: G45.3 (Amaurosis fugax)
• Secondary Diagnoses:
  • I65.21 (Right carotid stenosis) - if found
  • Z79.82 (Long-term use of aspirin) - if appropriate
• Outpatient Status: Use G45.3 as first-listed

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Example 4: With Subsequent Stroke

Scenario: Patient admitted with amaurosis fugax right eye. On day 2 of admission develops right MCA stroke before planned carotid endarterectomy.

Coding:

• Principal Diagnosis: I63.311 (Cerebral infarction due to thrombosis of right middle cerebral artery)
• Secondary Diagnoses:
  • G45.3 (Amaurosis fugax) - may still code as it was present on admission
  • I65.21 (Occlusion and stenosis of right carotid artery)
  • I69.351 (Hemiplegia following cerebral infarction affecting right side) - if applicable
• MS-DRG: 061-066 range (Ischemic Stroke)

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Example 5: History Only - NOT Coded

Scenario: Patient presents for carotid endarterectomy. Had episode of amaurosis fugax 6 months ago, no recent episodes.

Coding:

• Principal Diagnosis: I65.21 (Occlusion and stenosis of right carotid artery)
• Secondary: Z86.73 (Personal history of TIA) - NOT G45.3
• Procedure: 03CH0ZZ (Carotid endarterectomy)

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Example 6: Bilateral Carotid Disease with Amaurosis Fugax

Scenario: 70-year-old with episode of left eye amaurosis fugax. Workup reveals bilateral carotid stenosis (80% left, 60% right).

Coding:

• Principal Diagnosis: G45.3 (Amaurosis fugax)
• Secondary Diagnoses:
  • I65.22 (Occlusion and stenosis of left carotid artery)
  • I65.21 (Occlusion and stenosis of right carotid artery)
• MS-DRG: 069 or 071 depending on CC/MCC

Related ICD-10 Codes

Within Same Category (G45.-)

• G45.0: Vertebro-basilar artery syndrome
• G45.1: Carotid artery syndrome (hemispheric)
• G45.2: Multiple and bilateral precerebral artery syndromes
• G45.4: Transient global amnesia
• G45.8: Other transient cerebral ischemic attacks
• G45.9: Transient cerebral ischemic attack, unspecified

Commonly Co-reported Codes

• I65.2-: Occlusion and stenosis of carotid artery
• I48.-: Atrial fibrillation
• I10: Essential hypertension
• E78.5: Hyperlipidemia, unspecified
• E11.-: Type 2 diabetes mellitus
• H34.1-: Central retinal artery occlusion (if progresses to permanent)

Clinical Pearls for Coders

1. Amaurosis fugax is always a TIA - even though it’s an eye symptom, it’s coded in the neurological chapter because it’s a cerebrovascular event

2. Do not confuse with:

   • H34.- codes (permanent retinal artery occlusion)
   • H53.1- codes (subjective visual disturbances without organic cause)
   • G43.B- codes (retinal migraine - different pathophysiology)

3. Risk adjustment impact: This code has significant RAF value, ensure proper documentation

4. POA indicator: Critical for DRG payment - must indicate if present on admission

5. Workup codes: Don’t forget to code the imaging studies performed (carotid ultrasound, MRA, echocardiogram) as they affect DRG in some cases

6. Provider type matters: For HCC capture, ensure attending physician documents the diagnosis

7. Duration documentation: Although not required for code assignment, documenting symptom duration helps differentiate from completed stroke

8. Laterality documentation: While the code doesn’t have laterality, clinical documentation should specify which eye for clinical care continuity

References for Further Study

• ICD-10-CM Official Guidelines for Coding and Reporting
• CMS-HCC Risk Adjustment Model V24/V28
• MS-DRG Definitions Manual (Current FY)
• AHA Coding Clinic guidance on cerebrovascular conditions
• American Academy of Neurology Practice Parameters on TIA evaluation

Update History

• FY2025: No changes to code structure or definition
• V28 HCC: Continues to map to HCC 100