What H42 covers · when clinicians use it
ICD-10 code H42 identifies Glaucoma in diseases classified elsewhere in the U.S. ICD-10-CM clinical and billing record set. It sits within the Eye and Adnexa chapter (H00–H59), the section that groups related diagnoses so providers, payers, and public-health agencies report them consistently. Clinicians and medical coders apply H42 when an encounter's findings match the Glaucoma in diseases classified elsewhere description, attaching it to the patient record so downstream insurance claims, payer audits, quality reporting, and epidemiological surveillance all reference the same standardized diagnosis. The ICD-10-CM is maintained by the Centers for Medicare & Medicaid Services and the CDC's National Center for Health Statistics, with an updated official code set released each U.S. fiscal year — always verify H42 against the current CMS/CDC release and your payer's documentation guidance before final use. This page summarizes documentation context for H42 and is a coding reference, not clinical, diagnostic, or billing advice.
H42 refers to Glaucoma in diseases classified elsewhere, a group of eye diseases characterized by optic nerve damage commonly associated with elevated intraocular pressure (IOP). If untreated, glaucoma can lead to irreversible vision loss and is a leading cause of blindness worldwide.
Symptoms
- Gradual peripheral vision loss – Typical of open-angle glaucoma (H40)
- Severe eye pain and headache – Often seen in acute angle-closure glaucoma
- Halos around lights – Associated with increased IOP
- Redness and blurred vision – Signs of acute glaucoma attack
- Vision deterioration secondary to systemic disease – Found in H42 (e.g., diabetes, uveitis)
- Difficulty adjusting to darkness – Due to impaired optic nerve function
- Nausea or vomiting – Can accompany sudden IOP spikes
Diagnosis
Diagnosis of Glaucoma in diseases classified elsewhere includes tonometry (IOP measurement), optic nerve evaluation, visual field testing, gonioscopy, and optical coherence tomography (OCT). Early detection is critical to prevent vision loss.
ICD10 Code Usage
ICD10 code H42 is used by ophthalmologists and optometrists in routine screenings, surgical referrals, chronic disease management, and systemic disease tracking. It also supports insurance documentation for glaucoma medications, laser treatments, and surgical procedures.
Related Codes
FAQs
Q1: What is ICD10 code H42?
A: It designates Glaucoma in diseases classified elsewhere, referring to optic nerve damage often linked to high eye pressure and requiring long-term management.
Q2: Can glaucoma be cured?
A: No, but early diagnosis and treatment can prevent or slow vision loss.
Q3: What treatments are available?
A: Options include medicated eye drops, laser trabeculoplasty, filtering surgery, or minimally invasive glaucoma surgery (MIGS).
Q4: What is secondary glaucoma (H42)?
A: It occurs due to systemic or ocular conditions like uveitis, trauma, or steroid use.
Q5: Who manages glaucoma?
A: Ophthalmologists primarily, with optometrists involved in monitoring and initial detection.
Conclusion
ICD10 code H42 helps ensure early identification, treatment planning, and long-term management of Glaucoma in diseases classified elsewhere, preventing vision impairment and enhancing patient outcomes through regular monitoring and intervention.