H34.212

🧬 ICD-10-CM H34.212 - Partial Retinal Artery Occlusion, Left Eye

📋 Code Identity

Field	Detail
ICD-10-CM Code	H34.212
Full Descriptor	Partial Retinal Artery Occlusion, Left Eye
Includes (per Tabular)	Hollenhorst’s plaque; Retinal microembolism
Code Type	ICD-10-CM Diagnosis (Billable)
Effective Date	FY 2026 (October 1, 2025 - September 30, 2026)
Chapter	7 - Diseases of the Eye and Adnexa (H00-H59)
Block	H30-H36 - Disorders of Choroid and Retina
Parent Category	H34 - Retinal Vascular Occlusions
Subcategory	H34.21 - Partial Retinal Artery Occlusion
Laterality	6th character = 2 (Left Eye)
Billable?	✅ Yes — 6 characters, fully specified
Chronic vs. Acute	Acute/subacute — this is an embolic/ischemic event
Urgent Referral Indicated?	✅ Yes — cardiovascular/neurovascular workup urgently indicated
CC/MCC Status	Non-CC / Non-MCC
Excludes 1	Amaurosis fugax G45.3 — cannot be coded with H34.212

⚠️ Laterality: ICD-10-CM H34.212 is left eye only. Use H34.211 for the right eye, H34.213 for bilateral, and H34.219 for unspecified eye. Never default to unspecified when laterality is documented.

🔴 Excludes 1 — Critical: G45.3 (Amaurosis fugax) is an Excludes 1 code to the entire H34 category — meaning amaurosis fugax and retinal artery occlusion are mutually exclusive in ICD-10-CM. If the transient visual loss fully resolved with no evidence of embolic occlusion on exam, code G45.3. If a Hollenhorst plaque or microembolism is identified on fundoscopy (permanent lodged embolus, even if partial obstruction), code H34.212. Do not code both on the same claim.

🚨 MEDICAL URGENCY NOTE: A partial retinal artery occlusion — particularly one associated with a visible Hollenhorst plaque or retinal microembolism — is a systemic vascular emergency. It signals active thromboembolic disease, most commonly from the ipsilateral carotid artery or cardiac sources. The AHA and AAO both recommend urgent neurological and cardiovascular evaluation. As a coder, flag these encounters for complete systemic comorbidity coding — the RAF-generating diagnoses are upstream.

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🔬 Clinical Description

Partial retinal artery occlusion (PRAO) represents an incomplete occlusion of a retinal artery — typically the central retinal artery (CRA) or one of its branches — where blood flow is significantly reduced but not entirely interrupted. Unlike a complete central retinal artery occlusion (CRAO) H34.12 where all perfusion is lost and vision loss is typically sudden and profound, or a branch retinal artery occlusion (BRAO) H34.232 where a specific sectoral arterial branch is occluded, a partial RAO implies:

• Partial luminal obstruction of a retinal artery by an embolus that is lodged but not fully occluding flow
• Reduced perfusion pressure in the arterial segment distal to the obstruction
• Variable visual loss — from subtle visual field defects or mild acuity reduction to significant but incomplete vision loss, depending on degree and location of obstruction
• Transient white retinal opacification (if ischemia is sufficient) vs. a visible cholesterol crystal or embolic plaque lodged at an arterial bifurcation

The Hollenhorst Plaque — Core Clinical Finding

The ICD-10-CM Tabular List explicitly includes “Hollenhorst’s plaque” and “retinal microembolism” within the H34.21 subcategory. This makes H34.212 the correct code whenever a Hollenhorst plaque or retinal microembolism is identified in the left eye, regardless of whether the patient is currently symptomatic.

Hollenhorst plaques (named after ophthalmologist Robert W. Hollenhorst, who first described them in 1961) are cholesterol microemboli — bright, refractile, yellow-orange crystalline deposits — visible at retinal arterial bifurcations on fundoscopy. Key features:

• Origin: Cholesterol emboli typically arise from atheromatous plaques in the ipsilateral carotid artery (most commonly the left internal carotid artery for left eye findings), the aortic arch, or cardiac valvular disease
• Composition: Primarily cholesterol crystals (Hollenhorst plaques), but may also be calcific (white, dull — from cardiac valves or calcified carotid plaque) or fibrin-platelet (gray, dull — from cardiac sources or arterial thrombus)
• Behavior: Cholesterol emboli are often smaller than the arterial lumen and wedge at bifurcation points without completely occluding flow — hence “partial” occlusion. They may be asymptomatic (discovered incidentally on routine dilated exam) or cause transient or mild persistent visual symptoms
• Significance: Even an asymptomatic Hollenhorst plaque represents evidence of active thromboembolic disease in the carotid or cardiac circulation. Studies have demonstrated significantly elevated long-term risks of stroke, myocardial infarction, and cardiovascular mortality in patients with incidentally discovered Hollenhorst plaques

Embolus Types in Partial RAO

Embolus Type	Appearance	Source	Significance
Cholesterol (Hollenhorst plaque)	Bright, yellow-orange, refractile, shiny	Carotid atheroma, aortic arch	Most common; signals carotid disease; partial occlusion typical
Calcific embolus	White, dull, non-refractile	Cardiac valves (aortic stenosis), calcified carotid plaque	Often larger; more likely to cause complete/branch occlusion
Fibrin-platelet embolus	Gray, dull, elongated	Cardiac (A-fib, endocarditis), arterial thrombus	May fragment and migrate; associated with cardiac sources
Septic embolus	Variable; may cause retinal infiltrate	Endocarditis	Rare; requires systemic antibiotic workup; culture-negative endocarditis workup
Fat/amniotic (rare)	Variable	Trauma, long bone fracture, pregnancy	Rare; workup driven by clinical context

Pathophysiology

1. Embolus formation — Atherosclerotic plaque rupture in the left carotid artery (or cardiac source) releases cholesterol crystals, fibrin-platelet aggregates, or calcific fragments into the arterial circulation.
2. Embolus transit — The embolus travels through the left ophthalmic artery → left central retinal artery → bifurcations of the retinal arterial tree, where it lodges at a point of narrowing.
3. Partial luminal obstruction — If the embolus is smaller than the arterial lumen or lodges at a bifurcation point, flow is reduced but not fully interrupted — producing partial ischemia downstream.
4. Ischemic cascade — Reduced perfusion pressure → inner retinal ischemia → loss of axoplasmic transport in retinal ganglion cell axons → white opacification of the ischemic retinal segment (if significant enough). The degree of opacification and visual loss corresponds to the degree of perfusion reduction.
5. Spontaneous embolus migration — Cholesterol emboli may migrate distally or fragment, potentially restoring partial flow. This can produce transient or fluctuating visual symptoms — but the plaque remains visible at the new lodging point.
6. Permanent lodging — Many Hollenhorst plaques remain permanently lodged at their bifurcation point, visible on fundoscopy indefinitely, without ongoing ischemia once blood flow re-establishes via collaterals or partial recanalization.

Visual Impact

Degree of Partial Occlusion	Typical Visual Presentation	Fundoscopic Finding
Minimal (small embolus, high-flow vessel)	Asymptomatic or brief transient visual blur	Visible Hollenhorst plaque at bifurcation; no retinal whitening
Moderate (significant flow reduction)	Sector visual field defect; mild acuity reduction	Sector retinal whitening downstream of embolic plaque; plaque visible
Severe partial (near-complete occlusion)	Dense sectoral VF loss; significant acuity reduction; may mimic BRAO	Diffuse retinal whitening in affected sector; box-carring of arterial column
Fluctuating (migrating embolus)	Transient monocular visual loss episodes; amaurosis-like but embolus confirmed	Embolus visible at varying bifurcation points on serial exams

Imaging Findings

Modality	Active/Acute Findings	Chronic/Resolved Findings
Fundus Photography	Bright refractile yellow-orange plaque at arterial bifurcation; segmental retinal whitening; box-carring of arterial blood column	Persistent plaque (may remain permanently); retinal whitening resolves over weeks; inner retinal atrophy possible
Fluorescein Angiography (FA)	Delayed arterial filling distal to plaque; focal hypofluorescence at occlusion site; segmental arterial non-perfusion; possible RAPD on clinical exam	Residual arterial wall staining at plaque site; restored flow if embolus migrated
OCT Posterior Segment	Hyperreflective thickening of inner retinal layers (ischemic edema); loss of inner plexiform layer in affected sector; disc edema if pre-laminar ischemia	Inner retinal layer thinning/atrophy in ischemic zone; GCC (ganglion cell complex) thinning on OCT
OCTA	Loss of superficial and deep capillary plexus flow in ischemic sector; visible plaque as flow void in arterial tree	Persistent capillary non-perfusion in ischemic zone; may show collateral vessel formation
OCT Optic Nerve	Disc edema possible acutely if CRA involvement	RNFL thinning in affected sector chronically

Systemic Workup — Urgency Protocol

🚨 Partial RAO is a neurological and cardiovascular emergency. The following workup is typically recommended urgently:

Workup Element	Rationale	Typical Timeframe
Carotid artery duplex ultrasound	Identify ipsilateral carotid atherosclerosis as embolic source	Urgent — same day or within 24 hours
Cardiac evaluation / ECG	Identify atrial fibrillation, valvular disease as cardioembolic source	Urgent
Echocardiogram (TTE or TEE)	Assess for valvular disease, intracardiac thrombus, PFO	Within 24-48 hours
MRI brain with DWI	Rule out concurrent ischemic stroke; DWI detects acute ischemia	Urgent — same day or ED referral
Fasting lipids / CRP	Assess atherosclerotic risk factor profile	Urgent outpatient labs
CBC, coagulation studies	Rule out hematologic cause (thrombocytosis, hypercoagulable state)	Urgent
Blood pressure measurement	Hypertension is a major risk factor	Immediate
HbA1c / fasting glucose	Diabetes as vascular risk factor	Urgent
ESR / CRP	Rule out giant cell arteritis in patients ≥ 50 years	Urgent in appropriate age group

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🌳 Code Tree

H34 - Retinal Vascular Occlusions
│
├── H34.0 - Transient Retinal Artery Occlusion
│   ├── H34.01 - Right eye
│   ├── H34.02 - Left eye
│   ├── H34.03 - Bilateral
│   └── H34.09 - Unspecified eye
│
├── H34.1 - Central Retinal Artery Occlusion (CRAO) — Complete
│   ├── H34.10 - Unspecified eye
│   ├── H34.11 - Right eye
│   ├── H34.12 - Left eye
│   └── H34.13 - Bilateral
│
├── H34.2 - Other Retinal Artery Occlusions
│   │
│   ├── H34.21 - Partial Retinal Artery Occlusion
│   │   *(includes: Hollenhorst's plaque; Retinal microembolism)*
│   │   ├── H34.211 - Right eye
│   │   ├── H34.212 - Left eye  ◀ THIS CODE
│   │   ├── H34.213 - Bilateral
│   │   └── H34.219 - Unspecified eye
│   │
│   ├── H34.23 - Retinal Artery Branch Occlusion
│   │   *(complete branch occlusion — more severe than partial)*
│   │   ├── H34.231 - Right eye
│   │   ├── H34.232 - Left eye
│   │   ├── H34.233 - Bilateral
│   │   └── H34.239 - Unspecified eye
│   │
│   └── H34.29 - Other Retinal Artery Occlusions
│       ├── H34.291 - Right eye
│       ├── H34.292 - Left eye
│       ├── H34.293 - Bilateral
│       └── H34.299 - Unspecified eye
│
├── H34.8 - Other Retinal Vascular Occlusions
│   ├── H34.81 - Central Retinal Vein Occlusion (CRVO)
│   │   ├── H34.8110 - Left eye, unspecified
│   │   ├── H34.8111 - Left eye, with macular edema
│   │   └── ...
│   └── H34.83 - Tributary (Branch) Retinal Vein Occlusion
│       └── ...
│
└── H34.9 - Unspecified retinal vascular occlusion

🔍 H34.212 vs. H34.232 vs. H34.12 — Key Distinctions:

Code	Description	Degree of Occlusion	Visual Impact	Embolus Type
H34.212	Partial RAO, left eye	Incomplete — flow reduced, not absent	Variable; often mild to moderate	Typically cholesterol (Hollenhorst)
H34.232	Branch RAO (BRAO), left eye	Complete occlusion of a branch artery	Sectoral VF loss; acuity reduced in affected area	Calcific, fibrin-platelet, or cholesterol
H34.12	Central RAO (CRAO), left eye	Complete central artery occlusion	Sudden, profound vision loss; may be NLP	Large calcific or thrombus; cardioembolic
H34.02	Transient RAO, left eye	Temporary — fully resolves	Transient monocular visual loss; amaurosis fugax pattern	Microembolus that migrates; or vasospasm

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✅ Includes

H34.212 explicitly includes the following per ICD-10-CM Tabular:

• Hollenhorst’s plaque, left eye — cholesterol crystal microembolus lodged at a retinal arterial bifurcation, left eye; whether symptomatic or an incidental finding on routine dilated exam
• Retinal microembolism, left eye — any microscopic embolic material (cholesterol, fibrin-platelet, calcific, or other) causing partial occlusion of a retinal artery in the left eye
• Partial occlusion of the central retinal artery, left eye — significant flow reduction in the CRA without complete cessation
• Partial occlusion of a retinal arterial branch, left eye — where occlusion is incomplete (flow persists) rather than complete (as in BRAO)
• Incidentally discovered cholesterol plaque, left eye — found on routine exam with no acute symptoms; still coded H34.212 when a plaque is confirmed on fundoscopy

🔍 Incidental Hollenhorst Plaque — Code It! Many coders encounter a dilated eye exam note that reads, “Incidental Hollenhorst plaque noted at the superior temporal arterial bifurcation, left eye — patient asymptomatic.” This is absolutely coded as H34.212. An asymptomatic Hollenhorst plaque is a finding of major systemic clinical significance (carotid atheroembolism), and it supports medical necessity for urgent vascular and neurological referral as well as carotid imaging.

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🚫 Excludes

Excludes 1 (CANNOT be coded together — mutually exclusive)

Excluded Code	Description	Rationale
G45.3	Amaurosis fugax	Amaurosis fugax = transient monocular visual loss with complete recovery and no permanent embolic finding; if a plaque is confirmed on fundoscopy → code H34.212, not G45.3; these are mutually exclusive; never code both

🔴 Excludes 1 Decision Tree:

• Transient visual loss, fully recovered, no plaque on fundoscopy → G45.3 (Amaurosis fugax)
• Transient visual loss, fully recovered, Hollenhorst plaque confirmed on fundoscopy → H34.212 (the plaque = structural embolic finding)
• Transient visual loss, fully recovered, transient arterial constriction or spasm suspected → H34.02 (Transient RAO, left eye)
• Persistent visual loss, embolus confirmed → H34.212 or H34.232 depending on completeness

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🏥 HCC (Hierarchical Condition Category)

Field	Detail
HCC Mapped?	❌ No — H34.212 does not directly map to CMS-HCC v28
RAF Score Contribution	None from this code alone
Risk Adjustment Clinical Relevance	High — through associated cardioembolic and vascular comorbidities

💰 RAF Strategy — The Systemic Comorbidities Are Where the Score Lives: H34.212 itself carries no HCC weight, but it is a sentinel finding for a cluster of heavily weighted HCC conditions. The encounter triggered by a partial RAO / Hollenhorst plaque finding is one of the highest-yield opportunities in ophthalmology to drive appropriate, documented HCC coding. Every systemic condition documented in the associated workup should be coded.

Code	Description	HCC?	RAF Notes
I65.22	Occlusion and stenosis of left carotid artery	✅ HCC 108	Most common cause of left Hollenhorst plaque; ipsilateral carotid
I65.21	Occlusion and stenosis of right carotid artery	✅ HCC 108	Less common for left eye; possible with crossover or bilateral disease
I48.91	Unspecified atrial fibrillation	✅ HCC 96	Cardioembolic source; among highest-risk partial RAO etiologies
I48.19	Persistent atrial fibrillation, unspecified	✅ HCC 96	More specific A-fib documentation
I25.10	Atherosclerotic heart disease, native CA	✅ HCC 88	Systemic atherosclerosis context
I70.212	Atherosclerosis of native arteries of extremities, left leg, w/o rest pain	✅ HCC 108	Generalized atherosclerosis
I63.512	Cerebral infarction, left MCA, unspecified	✅ HCC 100	If concurrent stroke discovered on MRI workup
E11.9	Type 2 DM without complications	✅ HCC 19	Major cardiovascular risk factor
E11.65	T2DM with hyperglycemia	✅ HCC 19	More specific diabetes coding
I10	Essential hypertension	❌ None	Ubiquitous comorbidity; no HCC but always code
E78.5	Hyperlipidemia, unspecified	❌ None	Atherosclerotic risk factor; no HCC
Z82.49	Family history of ischemic heart disease and other diseases of the circulatory system	❌ None	Risk context documentation

🎯 Coder Action Point: When H34.212 appears on an encounter, systematically review the chart for all documented cardiovascular, cerebrovascular, and metabolic conditions — these are the HCC opportunities. The ophthalmologist who discovers a Hollenhorst plaque and documents carotid stenosis, A-fib, or diabetes in the assessment is generating meaningful risk adjustment documentation.

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🏨 MS-DRG (Medicare Severity DRG)

Field	Detail
CC/MCC Status	⬜ Non-CC / Non-MCC — verify CMS MS-DRG v42
Primary MS-DRG (as PDx)	MS-DRG 124 - Other Disorders of the Eye with MCC
Primary MS-DRG (no CC/MCC)	MS-DRG 125 - Other Disorders of the Eye without MCC/CC
MDC	MDC 02 - Diseases and Disorders of the Eye
Inpatient Admission Likelihood	Moderate — partial RAO/Hollenhorst plaque is usually outpatient; inpatient admission more likely for concurrent acute neurological event (stroke) where neurology may drive the principal diagnosis
CMS MS-DRG Version	v42 (FY2026)

🏥 Inpatient Sequencing — Concurrent Stroke: If a patient with H34.212 is admitted inpatient and neuroimaging reveals a concurrent ischemic stroke, the stroke code (e.g., I63.512) becomes the principal diagnosis — not H34.212. In that case, H34.212 is a secondary diagnosis, and the MS-DRG assignment shifts entirely to MDC 01 (Diseases of the Nervous System), where stroke codes carry CC/MCC weight. This is one of the most clinically important sequencing scenarios in retinal vascular coding.

🏥 Inpatient Secondary Diagnosis Context: H34.212 frequently appears as a secondary diagnosis on admissions for:

• Carotid endarterectomy (CEA) — left carotid stenosis driven by Hollenhorst plaque discovery
• Cardiac ablation for A-fib after embolic workup
• TIA/stroke workup admission
• Carotid stenting procedures

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💊 Associated CPT Codes (Commonly Reported With H34.212)

wRVU values reflect 2025 CMS Medicare Physician Fee Schedule Final Rule.

Ophthalmology CPT Codes

CPT Code	Description	wRVU (Non-Fac)	wRVU (Facility)	Assistant Payable?	Relevance
92235	Fluorescein angiography with interpretation and report	0.92	0.92	No	Documents arterial perfusion, filling delay at plaque site, NPR zone; CMS LCD covered for H34.212
92134	OCT posterior segment with interpretation and report	0.00	0.00	No	Documents ischemic inner retinal thickening acutely; GCC/RNFL atrophy chronically
92137	OCT with OCT angiography (OCTA)	0.79	0.79	No	Maps capillary non-perfusion zone; NV monitoring; cannot bill same day as 92134
92133	OCT optic nerve with interpretation and report	0.00	0.00	No	RNFL thinning in ischemic sector; cannot bill same day as 92137
92250	Fundus photography with interpretation and report	0.00	0.00	No	Documents Hollenhorst plaque location, retinal whitening; essential baseline
99215	E/M, established patient, high complexity	2.85	2.85	No	High complexity justified by acute finding, systemic risk, urgent coordination
99205	E/M, new patient, high complexity	3.50	3.50	No	New diagnosis of partial RAO/Hollenhorst plaque
99254	Inpatient consultation, moderate-high complexity	5.30	5.30	No	Ophthalmology inpatient consult for embolic workup or stroke admission
99255	Inpatient consultation, high complexity	6.71	6.71	No	Complex inpatient consult with multiple comorbidities

Systemic Workup CPT Codes (Associated Non-Ophthalmology Procedures Driving Billing in Multidisciplinary Context)

CPT Code	Description	Billing Specialty	Relevance to H34.212
93880	Duplex scan of extracranial arteries, bilateral	Vascular Surgery / Radiology	Left carotid duplex — primary embolic source workup
93882	Duplex scan of extracranial arteries, unilateral	Vascular Surgery / Radiology	Unilateral left carotid study
93306	Echocardiography, transthoracic, complete	Cardiology	Cardiac embolic source evaluation
93312	Echocardiography, transesophageal	Cardiology	TEE for PFO, valvular disease, intracardiac thrombus
70553	MRI brain with contrast	Radiology / Neurology	Rule out concurrent ischemic stroke
70557	MRI brain + MRA without contrast	Radiology	Stroke and cerebrovascular workup
93000	Electrocardiogram, routine	Cardiology / PCP	Rule out A-fib as cardioembolic source

⚠️ Key NCCI / Billing Rules

• 92137 (OCTA) cannot be billed same day as 92134 or 92133 — NCCI edit
• 92235 (FA) is CMS LCD-covered for H34.212 under the Ophthalmic Angiography article — document medical necessity clearly
• Modifier -25 required when E/M + imaging (FA, OCT) billed on the same DOS
• 99215 vs. 99205 — use new vs. established patient rules; a patient referred from PCP for evaluation of a newly discovered Hollenhorst plaque would typically be a new patient to the retina/ophthalmology practice → 99205
• CMS OCT Posterior Segment LCD (A56916) lists H34.212 as a covered indication for 92134 and 92137

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🔧 Applicable Modifiers

Modifier	Description	Application with H34.212
-LT	Left side	Append to all CPT codes performed on or for the left eye
-RT	Right side	When fellow right eye also examined or imaged at the same encounter
-50	Bilateral procedure	Bilateral FA, OCT, or fundus photography same session
-25	Significant, separately identifiable E/M same day as procedure	Required when E/M + 92235, 92134, or 92137 on same DOS
-59	Distinct procedural service	When two procedures are genuinely distinct and separately documented
-26	Professional component	Physician interprets imaging performed at another facility
-TC	Technical component	Facility bills for technical imaging only
-GC	Service by resident under supervision	Teaching hospital context
-GA	ABN on file	Medicare beneficiary ABN obtained for potentially non-covered service
-57	Decision for surgery	E/M same day as decision for major surgical procedure (e.g., if CEA is being coordinated — note: CEA itself is not billed by ophthalmology)
-AI	Principal physician of record	When ophthalmologist assumes principal physician role during an inpatient encounter

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📝 Coding Examples

Example 1 — Incidental Hollenhorst Plaque Discovered on Routine Dilated Exam, Left Eye

A 67-year-old established female presents for routine annual dilated eye exam. She is asymptomatic with no visual complaints. Dilated fundus exam reveals a bright, refractile, yellow-orange Hollenhorst plaque at the superior temporal arterial bifurcation of the left eye. No retinal whitening, no RAPD. Right eye unremarkable. OCT left eye performed: no inner retinal thickening. FA confirms delayed filling in the left superior temporal arteriole with the plaque visible. Patient referred urgently to PCP for carotid duplex and cardiac evaluation. History: hypertension, hyperlipidemia.

Diagnosis Codes:

• H34.212 - Partial retinal artery occlusion, left eye (Hollenhorst plaque)
• I10 - Essential hypertension
• E78.5 - Hyperlipidemia, unspecified

CPT Codes:

• 99215 - 25 - E/M, established patient, high complexity (high MDM: new acute finding with urgent coordination of care; systemic risk)
• 92235 - LT - Fluorescein angiography, left eye
• 92134 - 50 - OCT posterior segment, bilateral
• 92250 - 50 - Fundus photography, bilateral (documents plaque location)

💡 High Complexity E/M Justification: An incidental Hollenhorst plaque discovery — even in an asymptomatic patient — qualifies for high-complexity MDM: (1) new presenting problem with uncertain prognosis, (2) independent interpretation of FA, (3) independent coordination of care with urgent PCP referral for vascular workup. Document all three in your MDM box.

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Example 2 — New Patient Referred for Acute Transient Visual Loss, Hollenhorst Plaque Confirmed

A 72-year-old male, new patient, referred urgently from his PCP after describing sudden painless visual dimming in the left eye lasting approximately 20 minutes, which then resolved. On dilated exam: a bright cholesterol plaque is visible at the inferior temporal arterial bifurcation of the left eye. Mild segmental retinal pallor is present inferior temporally, suggesting partial ischemia during the event. BP today: 182/96. ECG: normal sinus rhythm. OCT shows mild inner retinal thickening, inferior temporal left macula.

Diagnosis Codes:

• H34.212 - Partial retinal artery occlusion, left eye (Hollenhorst plaque with prior transient event — plaque confirmed, so H34.212 takes priority over G45.3)
• I10 - Essential hypertension (BP 182/96 documented)
• E78.5 - Hyperlipidemia (if documented)

CPT Codes:

• 99205 - -25 - E/M, new patient, high complexity
• 92250 - -50 - Fundus photography, bilateral (documents plaque)
• 92134 - -LT - OCT posterior segment, left eye (acute inner retinal changes)
• 92235 - -LT - FA, left eye (confirms partial arterial obstruction)

🔴 G45.3 vs. H34.212 Decision: The patient described amaurosis fugax-like symptoms, but the fundoscopic finding of a confirmed Hollenhorst plaque changes the code. The Excludes 1 note mandates that when a plaque is confirmed on exam, H34.212 is used — not G45.3. Document clearly that the plaque was visible and confirmed.

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Example 3 — Hollenhorst Plaque + Carotid Stenosis Confirmed on Workup

An established 74-year-old male returns after urgent referral for Hollenhorst plaque, left eye, discovered last visit. Carotid duplex (performed by vascular surgery) confirms 75% stenosis of the left internal carotid artery. Cardiology cleared him from a cardiac source. Patient counseled on stroke risk. CEA (carotid endarterectomy) planned by vascular surgery. Today: OCT posterior segment left eye confirms mild GCC thinning inferior temporally. Plaque still visible.

Diagnosis Codes (Ophthalmology Visit):

• H34.212 - Partial retinal artery occlusion, left eye (persistent Hollenhorst plaque)
• I65.22 - Occlusion and stenosis of left carotid artery (confirmed on duplex — HCC 108)
• I10 - Essential hypertension

CPT Codes:

• 99215 - -25 - E/M, established patient, high complexity (ongoing management, new data review, coordination)
• 92134 - -LT - OCT posterior segment, left eye (GCC thinning progression)
• 92250 - -LT - Fundus photography, left eye (persistent plaque documentation)

💰 HCC Alert: I65.22 (left carotid occlusion/stenosis) maps to HCC 108 and is a significant RAF-generating diagnosis. Confirm it is documented in the ophthalmology note based on the carotid duplex results. If the ophthalmologist documents the diagnosis and reviews/incorporates the vascular workup data in their note, it can be coded from that encounter.

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Example 4 — Partial RAO with Atrial Fibrillation as Source, Left Eye

A 78-year-old female, established patient, presents with a 1-day history of blurred left eye vision. Dilated exam: segmental retinal whitening inferiorly, left eye; small dull gray embolus visible at inferior branch — fibrin-platelet appearance. OCT confirms inner retinal thickening in the affected sector. ECG performed in office: confirms new-onset atrial fibrillation. Patient sent to ED for urgent evaluation and anticoagulation initiation.

Diagnosis Codes:

• H34.212 - Partial retinal artery occlusion, left eye (fibrin-platelet embolus; partial obstruction)
• I48.91 - Unspecified atrial fibrillation (newly diagnosed; HCC 96)
• I10 - Essential hypertension

CPT Codes:

• 99215 - -25 - E/M, established patient, high complexity
• 92134 - -LT - OCT posterior segment, left eye
• 92250 - -LT - Fundus photography, left eye

🚨 Emergency Referral Documentation: When the ophthalmologist discovers I48.91 (A-fib) on an in-office ECG and facilitates an ED referral, this is extraordinarily high-complexity MDM. Document: new diagnosis of A-fib, relationship to retinal embolism, decision to refer to ED, and cardiology coordination. This single encounter can be one of the most clinically significant in the patient’s year.

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Example 5 — Inpatient Consult, Stroke Admission, Hollenhorst Plaque Left Eye Found on Bedside Exam

An 81-year-old male admitted by neurology for left hemispheric TIA with amaurosis fugax. Ophthalmology consulted at bedside. Dilated fundus exam at bedside confirms Hollenhorst plaque at the left superior temporal arterial bifurcation. No acute retinal whitening. MRI confirmed small left MCA territory lacunar infarct. Carotid duplex: left carotid 80% stenosis.

Inpatient Profee Diagnosis Codes (Ophthalmology Consult):

• H34.212 - Partial retinal artery occlusion, left eye (Hollenhorst plaque — documented by ophthalmology)
• G45.3 — ❌ DO NOT use; Excludes 1 with H34.212
• (Neurology coding stroke/TIA separately as PDx)

CPT Codes (Ophthalmology Inpatient Consult):

• 99254 - Inpatient consultation, moderate-high complexity (profee)
• 92250 - -LT - Fundus photography at bedside (if portable equipment used)

🏥 Sequencing Note: H34.212 is a secondary diagnosis in this admission — the stroke/TIA is the PDx for neurology. The ophthalmology consult note should clearly document the Hollenhorst plaque finding and its correlation with the embolic event. Both the plaque and the carotid stenosis should be captured in the ophthalmology consultation coding.

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Example 6 — Bilateral Hollenhorst Plaques Discovered

A 69-year-old male presents with no visual symptoms. Routine dilated exam reveals Hollenhorst plaques in both eyes — right eye at superior nasal bifurcation and left eye at inferior temporal bifurcation. Bilateral FA performed.

Diagnosis Codes:

• H34.211 - Partial retinal artery occlusion, right eye (right eye plaque)
• H34.212 - Partial retinal artery occlusion, left eye (left eye plaque)
• (Or use H34.213 — Partial retinal artery occlusion, bilateral — when documentation describes both eyes equally)
• I10 - Essential hypertension (if documented)

CPT Codes:

• 99215 - -25 - E/M, established patient, high complexity
• 92235 - -50 - FA, bilateral
• 92250 - -50 - Fundus photography, bilateral

💡 Bilateral Note: H34.213 (bilateral) is appropriate when both eyes have confirmed partial RAO/Hollenhorst plaques at the same encounter. If the documentation specifies the location and laterality of each plaque separately and the clinical picture differs per eye, coding H34.211 + H34.212 preserves the most granular documentation. Bilateral is acceptable when both eyes are described equivalently.

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🔗 Related Diagnoses to Consider Coding Together

Code	Description	Relationship to H34.212
I65.22	Occlusion and stenosis of left carotid artery	Most common etiology of left Hollenhorst plaque; HCC 108
I65.21	Occlusion and stenosis of right carotid artery	Bilateral or crossover carotid disease
I48.91	Unspecified atrial fibrillation	Cardioembolic source; HCC 96
I25.10	Atherosclerotic heart disease	Systemic atherosclerosis; HCC 88
I70.92	Chronic total occlusion of artery of the extremities	Generalized atherosclerosis marker
I10	Essential hypertension	Major cardiovascular risk factor; ubiquitous comorbidity
E78.5	Hyperlipidemia, unspecified	Atherogenic lipid profile
E11.9	Type 2 DM without complications	HCC 19; major vascular risk
H34.211	Partial RAO, right eye	Contralateral plaque (bilateral disease)
H34.232	Branch RAO, left eye	If partial occlusion progresses to complete branch occlusion
H34.12	Central RAO, left eye	Most severe progression — complete CRA occlusion
H34.02	Transient RAO, left eye	If prior transient episodes occurred without plaque
H35.052	Retinal NV, unspecified, left eye	Late complication if ischemia drives NV
H43.12	Vitreous hemorrhage, left eye	Rare late complication
G45.3	Amaurosis fugax	Mutually exclusive (Excludes 1) — do NOT code with H34.212
I63.512	Cerebral infarction due to unspecified occlusion/stenosis, left MCA	Concurrent ischemic stroke discovered on MRI workup
Z82.49	Family history of ischemic heart disease	Risk documentation

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⚖️ H34.212 vs. G45.3 — Master Decision Guide

This is the single most critical coding decision at every encounter involving left eye transient visual loss or embolic findings.

Clinical Scenario	Correct Code	Rationale
Transient visual loss, fully resolved, no plaque on fundoscopy, no vascular finding	G45.3	Classic amaurosis fugax — no structural embolic finding
Transient visual loss, fully resolved, Hollenhorst plaque confirmed on fundoscopy	H34.212	Plaque = structural embolic finding; Excludes 1 takes effect
Asymptomatic patient, Hollenhorst plaque found incidentally on routine exam	H34.212	Incidental plaque still coded as partial RAO per ICD-10-CM Includes note
Persistent visual field defect, plaque visible at bifurcation	H34.212	Partial occlusion with partial ischemia — fits H34.21 definition
Complete sectoral vision loss, complete branch arterial occlusion on FA	H34.232	Branch RAO — complete occlusion, more severe than partial
Complete sudden profound visual loss, CRA completely occluded on FA	H34.12	CRAO — most severe; different code family entirely

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📌 ICD-9-CM Crosswalk

ICD-9-CM	Description
362.33	Arterial occlusion, retinal, partial
362.31	Central retinal artery occlusion (NOS)

📝 ICD-9-CM 362.33 had no laterality. ICD-10-CM’s laterality specificity in H34.21x enables far more precise tracking of ipsilateral carotid disease correlation with left vs. right eye embolic events — clinically and epidemiologically meaningful.

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🧑‍💻 Coder Pearls

1. An asymptomatic Hollenhorst plaque is always H34.212. Per the ICD-10-CM Tabular Includes note, “Hollenhorst’s plaque” is explicitly captured under H34.21x. Never under-code an incidental plaque as a “normal variant” or leave it uncoded — it is a major clinical finding.
2. Excludes 1 with G45.3 is absolute. Amaurosis fugax and partial RAO are mutually exclusive. The distinction is made by fundoscopy: plaque present → H34.212; no plaque → G45.3. Never code both.
3. Left eye = left carotid. When coding the systemic etiology, match laterality: left eye Hollenhorst plaque → suspect left carotid stenosis → I65.22. Right eye → I65.21. Document and code the confirmed etiology when available.
4. I65.22 = HCC 108. The left carotid stenosis that drives a left eye Hollenhorst plaque carries significant RAF weight. When the carotid workup is confirmed and documented, code it — even if it’s being managed by vascular surgery, the ophthalmologist can code confirmed diagnoses documented in the shared record.
5. I48.91 = HCC 96. Atrial fibrillation as a cardioembolic source is another major RAF opportunity discovered in the workup of partial RAO. If A-fib is confirmed on workup, code it.
6. Sequencing in concurrent stroke: If the patient has both H34.212 and a confirmed ischemic stroke (I63.x), the stroke typically sequences first in the inpatient setting. The stroke codes carry CC/MCC weight; H34.212 does not — but document both for clinical completeness.
7. FA is CMS-covered for H34.212. The CMS Ophthalmic Angiography LCD lists retinal artery occlusion codes as covered indications for 92235. Document the medical necessity (confirm plaque location, assess perfusion, rule out progression) clearly in the FA order.
8. High-complexity E/M is almost always justified. A new or known partial RAO with Hollenhorst plaque involves: (1) an undiagnosed problem with uncertain prognosis or a known chronic illness with exacerbation, (2) independent review of test results (FA, OCT, carotid duplex if reviewed), and (3) coordination of care with vascular surgery, neurology, or cardiology. This easily meets high-complexity MDM criteria under E/M 2021+ guidelines.
9. Serial monitoring is legitimate. Patients with known Hollenhorst plaques require regular follow-up to monitor for progression (new plaques, visual field changes, development of retinal NV from chronic ischemia). Document the medical necessity for each monitoring visit — stable plaque with documented monitoring rationale supports continued ophthalmology management.
10. Watch for downstream NV. Chronic partial arterial occlusion can drive retinal ischemia → VEGF upregulation → retinal NV. If H35.052 (retinal NV, left eye) develops in a patient with H34.212, both codes should be reported, with the underlying partial RAO as the etiology documented clearly.

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Sources: ICD-10-CM FY2026 Tabular List, CMS.gov; AAPC Codify H34.212 and H34.21 Subcategory; ECGWaves H34.212 Code Reference; FindACode H34.212; NIH StatPearls - Hollenhorst Plaque, NCBI Bookshelf; Ophthalmology Advisor - Retinal Artery Occlusion Signals Warning of Stroke/Heart Attack, Dec 2024; Cleveland Clinic Consult QD - Stroke Risk After Retinal Artery Occlusion, Jul 2025; PMC - Retinal Vein Occlusion and Stroke Association, Apr 2022; CMS Billing & Coding: Ophthalmic Angiography (FA/ICG) A56774 v22; CMS Billing & Coding: Posterior Segment OCT A56916 v25; CMS ICD-10-CM/PCS MS-DRG v42 Definitions Manual; ASRS Retina Coding for Beginners, Mar 2024; Optos 2025 Retinal Imaging CPT Codes and Rates; CMS 2025 Medicare Physician Fee Schedule Final Rule; Review of Ophthalmology - Coding and Reimbursement 2026 Update, Jan 2026