H18.7 vs Q13.4
H18.7 and Q13.4 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on H18.7
congenital malformations of cornea (Q13.3-Q13.4)
H18.7
Other and unspecified corneal deformities
Not billable
- Chapter 7
- Diseases of the eye and adnexa
- Section
- H15-H22
Q13.4
Other congenital corneal malformations
Billable
- Chapter 17
- Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders
- Section
- Q10-Q18
Use when the record says
- Congenital malformation of cornea NOS
- Microcornea
- Peter's anomaly
Indexed under
- Embryotoxon
- Keratomegaly
- Microcornea (congenital)
- Peter's anomaly
- Anomaly, anomalous › cornea (congenital) (unspecified type)
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027