H49.12 ICD-10-CM Code: Fourth [trochlear] nerve palsy, left eye
H49.12 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · free HCC coding tools
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FY 2026 Apr update / Diseases of the eye and adnexa (H00-H59) / Disorders of ocular muscles, binocular movement, accommodation and refraction (H49-H52)
H49.12
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceFourth [trochlear] nerve palsy, left eye
This condition involves weakness or paralysis of the fourth cranial nerve (trochlear nerve) on the left side, which controls one of the eye muscles responsible for downward and inward eye movement. Patients typically experience difficulty looking down and inward with the affected eye, often causing double vision and head tilting.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for H49.12. Check the code and parent instructions in the Code Book.
Excludes 2
Official- certain conditions originating in the perinatal period (P04-P96)Inherited from H00-H59, H49-H52, H49
- certain infectious and parasitic diseases (A00-B99)Inherited from H00-H59, H49-H52, H49
- complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from H00-H59, H49-H52, H49
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Inherited from H00-H59, H49-H52, H49
- diabetes mellitus related eye conditions (E09.3-, E10.3-, E11.3-, E13.3-)Inherited from H00-H59, H49-H52, H49
- endocrine, nutritional and metabolic diseases (E00-E88)Inherited from H00-H59, H49-H52, H49
- injury (trauma) of eye and orbit (S05.-)Inherited from H00-H59, H49-H52, H49
- injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from H00-H59, H49-H52, H49
- neoplasms (C00-D49)Inherited from H00-H59, H49-H52, H49
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from H00-H59, H49-H52, H49
- syphilis related eye disorders (A50.01, A50.3-, A51.43, A52.71)Inherited from H00-H59, H49-H52, H49
- nystagmus and other irregular eye movements (H55)Inherited from H00-H59, H49-H52, H49
- internal ophthalmoplegia (H52.51-)Inherited from H00-H59, H49-H52, H49
- internuclear ophthalmoplegia (H51.2-)Inherited from H00-H59, H49-H52, H49
- progressive supranuclear ophthalmoplegia (G23.1)Inherited from H00-H59, H49-H52, H49
Related Codes
Includes
OfficialNo Includes notes are included in this display for H49.12. Check the code and parent instructions in the Code Book.
Excludes 1
OfficialNo Excludes 1 notes are included in this display for H49.12. Check the code and parent instructions in the Code Book.
Code First
OfficialNo Code First sequencing instructions are included in this display for H49.12. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for H49.12. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for H49.12. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is H49.12 an HCC code?
No. H49.12 is a billable ICD-10-CM code with no mapping under the CMS-HCC V28 or V24 community payment models, and none under the ESRD, Part D RxHCC, or HHS-HCC models.
- Code
- H49.12
- Description
- Fourth [trochlear] nerve palsy, left eye
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF reference coefficient
- —
- Billable
- Yes
- Payment year
- 2026
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
H49.12 is the ICD-10-CM diagnosis code for fourth [trochlear] nerve palsy, left eye. This condition involves weakness or paralysis of the fourth cranial nerve (trochlear nerve) on the left side, which controls one of the eye muscles responsible for downward and inward eye movement. Patients typically experience difficulty looking down and inward with the affected eye, often causing double vision and head tilting. H49.12 sits in the ICD-10-CM chapter for diseases of the eye and adnexa (h00-h59), within the section covering disorders of ocular muscles, binocular movement, accommodation and refraction (h49-h52).
H49.12 is a billable ICD-10-CM code, but the current payload does not show a mapping under the CMS-HCC V28 or V24 community payment models, and none under the ESRD, Part D RxHCC, or HHS-HCC models. Do not assign risk adjustment value from this page when no source-backed mapping is shown; verify the applicable model and payment year.
Verify laterality is documented as left eye in the medical record before assigning the 'left eye' component of this code.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for H49.12 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.