Glaucoma ICD-10 Codes: H40 Staging, Laterality and the 7th Character Explained

A patient returns for a glaucoma follow-up. The right eye still has no field loss; however, the left eye now shows loss in both hemifields. That one visit needs two glaucoma ICD-10 codes, two stages and two laterality digits, and if any of them is off, the visual field, OCT or laser claim tied to it can deny.

Glaucoma ICD-10 codes are precise by design. Each H40 code carries the glaucoma type, the eye and, for most types, the disease stage. Below, we take each of those pieces in turn, then put them together the way they appear on real charts.

How Glaucoma ICD-10 Codes Are Built

Most staged glaucoma codes follow the same pattern. For example, take H40.1121, primary open-angle glaucoma, left eye, mild stage:

• H40.11 names the glaucoma type, here primary open-angle glaucoma (POAG).
• The 6th character gives laterality: 1 for right, 2 for left, 3 for bilateral and 9 for unspecified eye.
• The 7th character gives the stage, from 0 (unspecified) to 4 (indeterminate).

However, some codes have no eye indicator, such as H40.10X- for unspecified open-angle glaucoma. They use an X placeholder in the 6th position so the stage can still sit in the 7th. The AAO glaucoma quick reference maps every combination, and the H40 codes did not change in the FY2027 update effective October 1, 2026.

What Each Glaucoma Stage Indicates

The stage comes from the optic nerve exam and the visual field, and the physician must document it. Therefore, coders should not assign a stage from test results alone.

However, indeterminate (4) and unspecified (0) are not interchangeable. Indeterminate means the physician tried to stage the eye and could not; unspecified means no stage was recorded, which should prompt a query.

Coding Each Eye When Stages Differ

The ICD-10-CM Official Guidelines for glaucoma (Chapter 7) set three rules that decide how many codes a patient needs.

Same type and stage in both eyes

In that case, use the bilateral code with the shared stage, such as H40.1132 for moderate POAG in both eyes.

Same type, different stages

Code each eye separately when the code has an eye indicator, such as H40.1111 (right, mild) and H40.1123 (left, severe). For types without an eye indicator, such as H40.10X-, code the stage of the more severely affected eye.

Different types in each eye

Code each eye with its own type and stage, such as POAG in one eye and pigmentary glaucoma in the other.

Also, if the stage worsens during an inpatient stay, report the highest stage documented. Laterality errors are as common in glaucoma as in retinal coding; our guide to retinal detachment ICD-10 codes covers the same right, left and bilateral logic.

Glaucoma Suspect and Ocular Hypertension

Patients watched for glaucoma, but without confirmed damage, get codes from H40.0-. These codes take laterality but no stage:

• H40.01- Open angle with borderline findings, low risk
• H40.02- Open angle with borderline findings, high risk
• H40.03- Anatomical narrow angle (primary angle closure suspect)
• H40.04- Steroid responder
• H40.05- Ocular hypertension
• H40.06- Primary angle closure without glaucoma damage

Once the physician documents glaucomatous damage, move the patient to a staged H40 code. Suspect codes still support monitoring tests when the record shows the risk being tracked.

Which Glaucoma ICD-10 Codes Need a Stage

However, not every H40 code has a 7th character. As a result, knowing which ones do prevents both truncated codes and invented stages.

Types that require a stage

• Primary open-angle (H40.11-), low-tension (H40.12-), pigmentary (H40.13-) and capsular or pseudoexfoliation glaucoma (H40.14-)
• Chronic angle-closure glaucoma (H40.22-)
• Unspecified open-angle and primary angle-closure glaucoma (H40.10X-, H40.20X-)
• Secondary glaucomas from trauma, inflammation, other eye disorders or drugs (H40.3- through H40.6-), which use an X placeholder

Types without a stage

• Residual stage of open-angle glaucoma (H40.15-)
• Acute and intermittent angle-closure glaucoma (H40.21-, H40.23-) and residual angle-closure (H40.24-)
• Other specified types in H40.81- through H40.83-

For these, the code ends at laterality, so adding a stage makes the code invalid.

Linking H40 Codes to Tests and Procedures

Glaucoma ICD-10 codes are what support visual field testing, OCT of the optic nerve, laser trabeculoplasty and glaucoma surgery. Payers check that link closely, so:

• Match the eye. For example, a left-eye laser procedure needs a left-eye or bilateral glaucoma code.
• Keep the stage current. If the latest field shows progression, the claim should carry the new stage, not last year’s.
• Use suspect codes carefully. Payers often cover monitoring tests for H40.0- patients at lower frequencies than for confirmed glaucoma.

For the procedure side of glaucoma care, see our post on cataract and glaucoma billing, and for broader specialty rules, our ophthalmology billing and coding guide.

Check Your Coding: Three Charts, Three Codes

In each case, the stage in glaucoma ICD-10 codes comes from the physician note, not from the coder reading the test. Clear documentation habits, such as those in our ocular trauma coding shortcuts, make that easy to support.

Accurate H40 Codes Protect Every Glaucoma Claim

Glaucoma claims rarely fail because of the disease itself. Instead, they fail because the code does not match the chart: a missing stage, one bilateral code when each eye is at a different stage, or a suspect code left in place after damage is confirmed. So getting the type, eye and stage right at every visit keeps visual field, OCT and laser claims paid and makes audits far easier to pass.

For practices with a large glaucoma population, these gaps usually surface only after denials start to build. MBW RCM checks H40 coding against each test and procedure before claims go out, through dedicated ophthalmology billing services.

Glaucoma ICD-10 Codes FAQs