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H35.042

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🧬 ICD-10-CM H35.042 — Retinal Micro-Aneurysms, Unspecified, Left Eye

FY2026 ICD-10-CM | Chapter 7 | Billable | Chronic Condition

📋 Code at a Glance

FieldDetail
Full CodeH35.042
DescriptionRetinal micro-aneurysms, unspecified, left eye
ICD VersionICD-10-CM FY2026 (effective Oct 1, 2025)
Billable✅ Yes
Chronic Condition Indicator✅ Chronic
HCC V24 Mapping❌ Does not map
HCC V28 Mapping❌ Does not map
MS-DRGMDC 02 - Diseases & Disorders of the Eye
SpecialtyOphthalmology, Retina
Code AlsoI10 - Essential hypertension, if applicable

🔬 Clinical Description

Retinal microaneurysms are focal, saccular outpouchings (bulges) of the walls of the retinal capillaries. They are the earliest clinically detectable sign of retinal microvascular disease and appear as tiny, round, red dots on funduscopic examination, typically smaller than 125 microns in diameter. They occur primarily after the loss of pericytes — the supporting cells of the capillary wall — which weakens vascular integrity and allows focal ballooning of the capillary.

On fundus photography or fluorescein angiography (FA), microaneurysms appear as hyperfluorescent dots that leak dye due to breakdown of the blood-retinal barrier. Optical coherence tomography (OCT) may reveal associated intraretinal fluid if leakage is significant.

The term “unspecified” in H35.042 refers to the etiology being unspecified (i.e., not coded as diabetic, hypertensive, or otherwise attributed via a combination code). The laterality is clearly specified — this is the left eye. This code is used when the provider documents retinal microaneurysms in the left eye without attributing them to a specific systemic etiology in a way that would require a combination code.

Attention

⚠️ Coder Alert: If the microaneurysms are documented in the context of diabetic retinopathy, you should NOT use H35.042. Use the appropriate diabetes combination code instead (e.g., E11.3211, E11.3291, etc.), which inherently includes the retinal findings. H35.042 is for non-diabetic or etiology-unspecified microaneurysms.

🧬 Pathophysiology

Retinal microaneurysms develop through the following mechanism:

  1. Pericyte loss — Sustained hyperglycemia (or other insults like hypertension, hyperviscosity) triggers the selective apoptosis of pericytes, the mural cells that regulate capillary tone and support endothelial cells.
  2. Endothelial dysfunction — Without pericyte support, endothelial cells become disorganized, leading to focal weakening of the capillary wall.
  3. Focal ballooning — Intraluminal pressure causes the weakened capillary wall to bulge outward, forming a microaneurysm.
  4. Barrier breakdown — The compromised vessel wall leaks plasma proteins and fluid into the retina, contributing to hard exudates and macular edema if located near the macula.
  5. Progression risk — Microaneurysm counts correlate with disease progression; increasing number or turnover (new formation + resolution) is a risk marker for worsening retinopathy.

Common underlying etiologies when this code is used include:

  • Non-diabetic background retinopathy (hypertensive, radiation-associated, venous stasis)
  • Incidental finding without identified systemic cause
  • Observation/monitoring when etiology is still being worked up

🏥 HCC (Hierarchical Condition Category) Information

HCC ModelMappingNotes
CMS-HCC V24❌ No HCC assignmentDoes not map to a payment HCC
CMS-HCC V28❌ No HCC assignmentUnspecified retinal vascular changes do not map under V28
HHS-HCC (ACA)❌ No HCC assignmentNot a risk-adjustable condition under HHS model

Key Point for Risk Adjustment: H35.042 — as an unspecified retinal vascular finding — does not carry RAF weight under either V24 or V28 models. If the underlying etiology is diabetes, the RAF value is captured through the diabetes with retinopathy combination codes (E-codes). Coders working in the MA/risk adjustment space should query providers when microaneurysms are found in diabetic patients to ensure proper linkage via the combination code, not H35.042.

🌳 Code Tree

H35 — Other retinal disorders  
├── Excludes2: Diabetic retinal disorders  
│ (E08.311-E08.359, E09.311-E09.359, E10.311-E10.359,  
│ E11.311-E11.359, E13.311-E13.359)  
│ └── H35.0 — Background retinopathy and retinal vascular changes  
├── Code also any associated hypertension: [[I10]]  
├── H35.00 — Unspecified background retinopathy  
├── H35.01 — Changes in retinal vascular appearance  
├── H35.02 — Exudative retinopathy (Coats disease)  
├── H35.03 — Hypertensive retinopathy  
├── H35.04 — Retinal micro-aneurysms, unspecified ◀ PARENT  
│ ├── H35.041 — Right eye  
│ ├── H35.042 — Left eye ✅ THIS CODE  
│ ├── H35.043 — Bilateral  
│ └── H35.049 — Unspecified eye  
├── H35.05 — Retinal neovascularization, unspecified  
├── H35.06 — Retinal vasculitis (Eales disease)  
├── H35.07 — Retinal telangiectasis  
└── H35.09 — Other intraretinal microvascular abnormalities

✅ Includes

Under the parent category H35.0 - Background retinopathy and retinal vascular changes, included concepts encompass all forms of retinal vascular damage related to systemic vascular disease when not specifically attributable to diabetes (which has its own combination codes):

  • Hypertensive retinal changes
  • Non-diabetic vascular retinopathy
  • Retinal micro-aneurysms without specified etiology

🚫 Excludes

Excludes2 (under H35):

Diabetic retinal disorders — these are not included in H35.042 and must be coded separately using:

Attention

⚠️ An Excludes2 note means these conditions can technically coexist and both may be coded, but only if clinically distinct and separately documented. However, if the microaneurysm IS the diabetic retinopathy finding, use only the diabetes combination code — do NOT code H35.042 additionally.

📌 Code-Also Instruction

Per the tabular instruction under H35.0:

Code also any associated hypertension: I10

When hypertension is documented as an associated condition or contributing factor to the retinal vascular changes, sequence I10 as an additional code.

🏨 MS-DRG Assignment

H35.042 falls under:

  • MDC 02 — Diseases and Disorders of the Eye
  • Typically assigned to DRG 116 (Intraocular Procedures without CC/MCC) or DRG 117 (Intraocular Procedures with CC or MCC) if an inpatient procedure is performed
  • As a diagnosis-only (no surgical procedure), it would map to DRG 124 (Other Disorders of the Eye, without MCC) or DRG 125 (Other Disorders of the Eye, with MCC)

Practical note: Retinal microaneurysms are almost universally managed outpatient (ophthalmology office, retina clinic). Inpatient admission solely for H35.042 would be uncommon. This code is most frequently seen in the outpatient/office-based setting and on Evaluation & Management (E/M) encounters.

✏️ Coding Guidelines & Notes

  1. Laterality is required — Never code to the parent code H35.04 (non-billable). Always select:

    • H35.041 Right eye
    • H35.042 Left eye ← this code
    • H35.043 Bilateral
    • H35.049 Unspecified eye (only when documentation truly doesn’t specify)

  2. Do NOT use for diabetic patients when the microaneurysms are a manifestation of their diabetes. Use the diabetic retinopathy combination code from the E08-E13 range.

  3. When hypertension is documented as associated — add I10.

  4. Query opportunity: If a patient has known Type 2 DM and microaneurysms are noted without explicit documentation linking them, query the provider before defaulting to H35.042.

  5. Sequencing: In the outpatient setting, sequence the code for the condition most responsible for the encounter. If microaneurysm monitoring is the reason for the visit, H35.042 may be the first-listed code.

  6. Chronic condition — This is flagged as a chronic condition and should be reported at each visit when clinically documented as active/monitored.

📖 Coding Examples

Example 1 — Non-Diabetic Hypertensive Patient

“72-year-old female with essential hypertension presents to ophthalmology for routine retinal exam. Fundus shows microaneurysms in the left eye consistent with hypertensive retinopathy.”

Codes:

  • H35.042 — Retinal micro-aneurysms, unspecified, left eye
  • I10 — Essential hypertension

Example 2 — Incidental Finding, No Known Etiology

“58-year-old male, no significant PMH. Routine dilated eye exam reveals two microaneurysms in the left retina. Etiology unclear at this time; labs ordered.”

Code:

  • H35.042 — Retinal micro-aneurysms, unspecified, left eye

Example 3 — Diabetic Patient (DO NOT use H35.042)

“Patient with Type 2 DM presents for dilated retinal exam. Ophthalmologist notes mild nonproliferative diabetic retinopathy with microaneurysms in the left eye, without macular edema.”

Correct Code:

  • E11.3291 — Type 2 diabetes mellitus with mild nonproliferative diabetic retinopathy without macular edema, left eye

❌ Do NOT add H35.042 — the microaneurysms are subsumed in the combination code.

Example 4 — Bilateral Monitoring Encounter

“Patient returns to retina clinic for monitoring of known microaneurysms, left eye worse than right. Left eye: multiple microaneurysms. Right eye: single microaneurysm, stable.”

Codes:

  • H35.042 — Left eye (more severe, typically sequenced first)
  • H35.041 — Right eye

🔗 Related Codes

CodeDescription
H35.041Retinal micro-aneurysms, unspecified, right eye
H35.043Retinal micro-aneurysms, unspecified, bilateral
H35.049Retinal micro-aneurysms, unspecified, unspecified eye
H35.031Hypertensive retinopathy, right eye
H35.032Hypertensive retinopathy, left eye
H35.09Other intraretinal microvascular abnormalities
H35.052Retinal neovascularization, unspecified, left eye
I10Essential (primary) hypertension
E11.3291Type 2 DM with mild NPDR w/o macular edema, left eye
E11.3391Type 2 DM with moderate NPDR w/o macular edema, left eye
H35.062Retinal vasculitis, left eye
H35.072Retinal telangiectasis, left eye

Sources: ICD-10-CM Tabular List FY2026 (CMS/CDC); icd10data.com H35.042; AAPC ICD-10 Code Reference; ScienceDirect - Microaneurysm pathophysiology; CMS HCC V28 Model Mappings; icdlist.com H35.042

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