Question 1

What is ICD-10 code H18.603?

Accepted Answer

H18.603 is the ICD-10-CM diagnosis code for keratoconus, unspecified, bilateral. A condition where the cornea (clear front of the eye) becomes progressively cone-shaped in both eyes, without specification of whether it is stable or worsening. H18.603 sits in the ICD-10-CM chapter for diseases of the eye and adnexa (h00-h59), within the section covering disorders of sclera, cornea, iris and ciliary body (h15-h22).

H18.603 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

This bilateral code should only be used when keratoconus affects both eyes; if only one eye is affected, use the appropriate unilateral code.

Question 2

Is H18.603 an HCC code?

Accepted Answer

No. H18.603 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is H18.603 billable?

Accepted Answer

Yes. H18.603 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. H18.603 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

What is the V28 vs V24 difference for H18.603?

Accepted Answer

H18.603 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards H18.603 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting H18.603?

Accepted Answer

This bilateral code should only be used when keratoconus affects both eyes; if only one eye is affected, use the appropriate unilateral code If stability status is documented, use H18.613 (stable) or H18.623 (unstable) instead

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H18.603

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H18.603 ICD-10-CM Code: Keratoconus, unspecified, bilateral

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H18.603

Is H18.603 an HCC code?

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Child Codes

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Open H18.603 in the Interactive Encoder