11 ICD-10 coding

What does glaucoma diagnosis require from an ICD-10 coding standpoint?

A glaucoma diagnosis requires an appropriate ICD-10 code, with correct wording and staging.

Coding often requires specifying:

• Glaucoma type

• Laterality, when applicable

• Stage: mild, moderate, or severe

What open-angle glaucoma-related diagnoses are commonly coded separately?

Open-angle conditions include:

• Primary open-angle glaucoma

• Low-tension glaucoma

• Ocular hypertension

• Open angle with borderline findings, coded as glaucoma suspect

How should ocular hypertension and glaucoma suspect be distinguished from true glaucoma diagnoses?

• Ocular hypertension: elevated IOP without definite glaucomatous optic neuropathy or visual field loss

• Glaucoma suspect/open angle with borderline findings: suspicious optic nerve, IOP, OCT, or visual field findings without enough evidence for definite glaucoma

• Glaucoma: structural and/or functional glaucomatous damage

What angle-closure-related diagnoses should be distinguished in ICD-10 coding?

Angle-closure conditions include:

• Narrow anatomical angle → angle closure suspect

• Primary angle closure without glaucoma damage

• Acute angle closure glaucoma attack

• Intermittent angle-closure glaucoma

• Chronic angle-closure glaucoma

• Residual stage of angle-closure glaucoma

What is the coding distinction between narrow anatomical angle and primary angle closure without glaucoma damage?

• Narrow anatomical angle: patient is an angle closure suspect because anatomy is narrow or potentially occludable

• Primary angle closure without glaucoma damage: angle closure has occurred, but there is no glaucomatous optic nerve or visual field damage

How do acute, intermittent, chronic, and residual angle-closure glaucoma differ conceptually?

• Acute angle closure: sudden symptomatic IOP spike/attack

• Intermittent angle closure: episodic angle closure with IOP spikes that may normalize between episodes

• Chronic angle closure: persistent or repeated angle closure causing glaucomatous damage

• Residual stage: remaining damage after prior angle-closure disease

What secondary glaucomas require specific ICD-10 coding categories?

Secondary glaucoma categories include:

• Pigmentary glaucoma

• Capsular glaucoma with pseudoexfoliation of lens

• Glaucoma secondary to drugs

• Glaucoma secondary to eye trauma

• Glaucoma secondary to eye inflammation

• Glaucoma secondary to other eye disorders

Why is pigment dispersion/pigmentary disease important in glaucoma coding?

Pigment disease may be coded differently depending on whether glaucoma damage is present.

• Pigmentary glaucoma: pigment dispersion with glaucomatous damage

• Degeneration of iris/pigmentary condition without glaucoma: pigmentary findings without glaucoma damage

How should pseudoexfoliation be distinguished from pseudoexfoliative glaucoma in coding?

• Capsular glaucoma with pseudoexfoliation of lens: pseudoexfoliation with glaucomatous damage

• Other specified cataract/PXE-type condition without glaucoma: pseudoexfoliation-type finding without glaucomatous damage

What conditions may look related to glaucoma risk but are coded as conditions without glaucoma if no glaucomatous damage is present?

Conditions without glaucoma include:

• Degeneration of iris, including pigmentary findings

• Recession of chamber angle

• Other specified cataract, such as pseudoexfoliation-related lens findings

• Steroid responder

How does ICD-10 glaucoma staging differ from GSS staging?

GSS is used to stage visual field defects as mild, moderate, or severe for target pressure setting and disease management.

ICD-10 staging is broader and is used for billing and coding across all glaucoma types.

What are the key features of ICD-10 glaucoma staging?

ICD-10 glaucoma staging is:

• Used for billing and coding

• Broadly categorized as mild, moderate, or severe

• Used for all forms of glaucoma

• Coded separately for each eye

Why does glaucoma staging matter clinically beyond ICD-10 coding?

Staging helps guide:

• Target IOP selection

• Follow-up frequency

• Treatment intensity

• Monitoring strategy

How is mild or early-stage glaucoma defined for ICD-10 staging?

Mild or early-stage glaucoma includes optic nerve abnormalities consistent with glaucoma without standard visual field loss.

This is often called pre-perimetric glaucoma.

What does “pre-perimetric glaucoma” mean?

Pre-perimetric glaucoma means there are glaucomatous structural changes before visual field defects are detected on standard perimetry.

It may be detected by:

• OCT RNFL thinning

• Ganglion cell analysis changes

• Progressive optic nerve/rim changes

Key idea: Structure can show glaucoma before function does.

Why can OCT detect glaucoma earlier than visual field testing?

A patient may need to lose about 30% of retinal ganglion cells before visual field loss becomes detectable.

Therefore, OCT evidence of RNFL or GCA/GCC progression can identify glaucoma earlier than standard visual field testing.

Is it beneficial to detect and treat glaucoma at the pre-perimetric stage?

Yes. Early detection and treatment can help prevent progression to measurable visual field loss.

Clinical concept: Treating early disease may preserve retinal ganglion cells before functional damage is apparent.

How is moderate-stage glaucoma defined in ICD-10 staging?

Moderate-stage glaucoma means there are:

• Optic nerve abnormalities consistent with glaucoma

• Glaucomatous visual field abnormalities in one hemifield

• No involvement within 5 degrees of fixation

What visual field finding prevents a glaucoma case from being classified as moderate in ICD-10 staging?

Visual field loss within 5 degrees of fixation prevents classification as moderate.

If fixation is threatened or involved, disease is generally staged as more severe.

Why can a visual field be “mild” by GSS but “moderate” by ICD-10?

ICD-10 staging is broader and classifies any significant glaucomatous visual field loss in one hemifield as moderate, as long as fixation is not involved.

GSS may grade the same field as mild based on more detailed defect depth and extent.

How is advanced, late, or severe glaucoma defined in ICD-10 staging?

Severe glaucoma includes optic nerve abnormalities consistent with glaucoma plus visual field loss involving either:

• Both superior and inferior hemifields, or

• Loss within 5 degrees of fixation in at least one hemifield

What visual field findings upgrade glaucoma to severe stage in ICD-10?

Glaucoma is staged as severe if there is:

• Glaucomatous VF loss in both hemifields

• Or VF loss within 5 degrees of fixation

• Or fixation loss

Why can a visual field be “moderate” by GSS but “severe” by ICD-10?

ICD-10 staging is broader and emphasizes whether the defect affects both hemifields or threatens fixation.

A field that is moderate by detailed GSS criteria may still be coded as severe in ICD-10 if it involves:

• Superior and inferior hemifields, or

• The central 5 degrees near fixation

When should glaucoma be coded as indeterminate stage?

Indeterminate stage is used when the glaucoma stage cannot be determined because:

• Visual fields have not been performed yet

• Visual fields are consistently unreliable

• Patient cannot perform VF testing due to factors such as intellectual/developmental disability, dementia, or physical limitations

What is the difference between indeterminate and unspecified glaucoma stage?

• Indeterminate: stage cannot be determined despite appropriate reason, such as no reliable VF testing

• Unspecified: stage was not recorded or documented in the chart

Exam/coding pearl:
Use indeterminate when staging is truly not possible. Avoid unspecified because it usually reflects poor documentation.

Why should “unspecified stage” generally be avoided in glaucoma coding?

“Unspecified” indicates that the glaucoma stage was not documented in the record.

What ICD-10 category is used for a glaucoma suspect with open angles and borderline findings?

A glaucoma suspect with open angles and borderline findings is coded under open angle with borderline findings.

This applies when the patient has risk factors or suspicious findings but does not yet meet criteria for definite glaucoma.

How is low-risk versus high-risk open-angle glaucoma suspect determined for ICD-10 coding?

ICD-10 coding uses the number of defined risk factors:

• Low risk: 2 or fewer risk factors

• High risk: 3 or more risk factors

What risk factors are used for open-angle glaucoma suspect ICD-10 coding?

ICD-10 coding risk factors include:

• African American or Hispanic race

• Family history of glaucoma in a first-degree relative

• Thin central corneal thickness

• High IOP

• Pseudoexfoliation or pigment dispersion syndrome

What is the key difference between a glaucoma suspect and definite glaucoma?

• Glaucoma suspect: open angle with suspicious or borderline findings, but insufficient evidence of definite glaucomatous damage

• Definite glaucoma: optic nerve/RNFL/GCC damage and/or reproducible glaucomatous visual field loss

What is the main purpose of GSS compared with ICD-10 glaucoma staging?

GSS is used for detailed visual field interpretation, precise disease staging, disease management, and setting target pressures.

ICD-10 is used for diagnosis documentation in the EHR and billing/insurance coding.

High-yield distinction:
GSS = clinical management tool
ICD-10 = coding/documentation tool

What visual field features does GSS use to stage glaucoma severity?

GSS uses more precise visual field data, including:

• Mean deviation

• Precise involvement of points within fixation, especially from the decibel plot

• Number of flagged points on the pattern deviation plot

• Number of severe flagged points on the pattern deviation plot

What visual field features does ICD-10 use to stage glaucoma severity?

ICD-10 uses broader visual field features, including:

• Broad defects on the pattern deviation plot

• Whether defects involve one or both hemifields

• Whether flagged points involve the central field

• Central involvement does not require detailed interpretation of decibel level

Why can the same visual field receive different severity labels under GSS and ICD-10?

GSS uses detailed quantitative VF interpretation, including mean deviation, decibel depth, and number of flagged points.

ICD-10 uses broader coding categories based on hemifield involvement and central flagged points.

Therefore, a field may be:

• Mild by GSS but moderate by ICD-10

• Moderate by GSS but severe by ICD-10