2027 ICD-10-CM Diagnosis Code H49.42Progressive external ophthalmoplegia, left eye
ICD-10-CM Codes›H00–H59›H49-H52›H49
- Billable — Valid for Submission
- Not Chronic
H49.42 is a billable ICD-10-CM diagnosis code for progressive external ophthalmoplegia, left eye. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 123. Coders also document this condition as external ophthalmoplegia of left eye. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Neuro-ophthalmology and Strabismus.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- External ophthalmoplegia of left eye
- Left progressive external ophthalmoplegia
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to H49.42: its own notes plus those printed at H49.4, H49, block H49-H52, and Chapter 7. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- nystagmus and other irregular eye movements (H55)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- diabetes mellitus related eye conditions (E09.3-, E10.3-, E11.3-, E13.3-)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury (trauma) of eye and orbit (S05.-)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
- syphilis related eye disorders (A50.01, A50.3-, A51.43, A52.71)
Notes
General instructions on how these codes are used.
- Use an external cause code following the code for the eye condition, if applicable, to identify the cause of the eye condition
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Ophthalmoplegia, Chronic Progressive External
a mitochondrial myopathy characterized by slowly progressive paralysis of the levator palpebrae, orbicularis oculi, and extraocular muscles. ragged-red fibers and atrophy are found on muscle biopsy. familial and sporadic forms may occur. disease onset is usually in the first or second decade of life, and the illness slowly progresses until usually all ocular motility is lost. (from adams et al., principles of neurology, 6th ed, p1422)
Patient EducationClinical
Eye Movement Disorders
When you look at an object, you're using several muscles to move both eyes to focus on it. If you have a problem with the muscles, the eyes don't work properly.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert H49.42 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About H49.42Overview
What is the ICD-10 code for progressive external ophthalmoplegia, left eye?
The ICD-10-CM code for progressive external ophthalmoplegia, left eye is H49.42 (sometimes written as H4942). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is H49.42 (Progressive external ophthalmoplegia) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report progressive external ophthalmoplegia, left eye on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does H49.42 group to?
When progressive external ophthalmoplegia, left eye is the principal diagnosis on an inpatient stay, it groups to MS-DRG 123 (neurological Eye Disorders), which carries a relative weight of 0.8218. Higher weights mean higher Medicare reimbursement.
Can H49.42 be reported with a code from H49.81?
Not as a rule. The Excludes1 note at H49.4, which applies to H49.42, lists "Kearns-Sayre syndrome (H49.81-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What is the ICD-9 equivalent of H49.42?
Under the General Equivalence Mappings, progressive external ophthalmoplegia, left eye converts to ICD-9-CM 378.55 (external ophthalmoplegia). The mapping is approximate, so confirm the match fits the documentation.
