Defining Keratoconus Progression for Cross-Linking Treatment

iLink corneal cross-linking, the only cross-linking procedure approved by the FDA and covered by insurance, is indicated for the treatment of progressive keratoconus. Keratoconus progression often needs to be proven to ensure the procedure can be covered by insurance, but how do you identify progression in your patients? A recent blog post by Sumit “Sam” Garg on Healio sought to address this question.

While there are numerous factors that go into determining the progression of keratoconus, there are three key elements that must be considered for your patients’ eligibility for cross-linking:

  • Clear evidence of keratoconus progression
  • The risk category of the patient
  • Potential documentation needed to secure third-party reimbursement

Evidence of Keratoconus Progression

A 2015 consensus paper in Cornea defines keratoconus progression as a change in the steepening of the anterior and posterior corneal surfaces, and the thinning and/or increase in the rate of corneal thickness change from the periphery to the thinnest point.

They also note that magnitude of the change must be above the normal variability of the measurement system; a meaningful increase in Kmax is what matters most.

Patient Vision & Risk Factor

Age and visual acuity are not part of the consensus definition of keratoconus progression but are important for clinical analysis. A patient younger than 30 years old with rapidly increasing myopia or astigmatism needs to be observed cautiously and consistently.

If too much time is taken to determine cross-linking eligibility in these high-risk scenarios, then the patient could progress beyond the mild stage of keratoconus before treatment is administered.

Keratoconus Progression Definitions from Third-Party Payers

It is also important to consider the definitions of keratoconus progression established by payers, as this can affect your patients’ access to treatment. Know what requirements are established for cross-linking reimbursement and be sure to serve as an advocate for your patients when they need to be treated.

For example, Anthem Blue Cross Blue Shield defines progress as any of the following changes occurring within 24 months of cross-linking treatment:

  1. Increase of 1.00 diopters (D) or more in the steepest keratometry measurement; or
  2. Increase of 1.00 D or more in manifest cylinder; or
  3. Increase of 0.50 D or more in manifest refraction spherical equivalent (MRSE)

Importance of Early Keratoconus Diagnosis & Documenting

Since 70% of keratoconus presents through optometry, optometrists also play a critical role not only in identification and treatment of the disease, but also in documentation of progression. Often their clinical findings can help to meet the requirements of payers and establish the medical necessity of cross-linking for the basis of insurance coverage.

Documenting progression to secure third-party reimbursement should be a collaborative effort between optometrists and ophthalmologists. It can directly impact a patient’s insurance coverage, and therefore access to treatment. It is critically important to work with your referring physicians to make sure they are aware of the specific criteria needed to evidence progression so that they can track this over time for their keratoconus patients and provide historical charts when warranted.

For further analysis on the definition of keratoconus progression for cross-linking treatment, click here.

Using Photrexa® Viscous (riboflavin 5’-phosphate in 20% dextran ophthalmic solution), Photrexa® (riboflavin 5’-phosphate ophthalmic solution), and the KXL® System, the iLink™ corneal cross-linking procedure from Glaukos is the only FDA-approved therapeutic treatment for patients with progressive keratoconus and corneal ectasia following refractive surgery.*1

[Photrexa IFU/p1/col1/para3/lines1-4]


Photrexa® Viscous (riboflavin 5’-phosphate in 20% dextran ophthalmic solution) and Photrexa® (riboflavin 5’-phosphate ophthalmic solution) are indicated for use with the KXL System in corneal collagen cross-linking for the treatment of progressive keratoconus and corneal ectasia following refractive surgery.

Important Safety Information

Corneal collagen cross-linking should not be performed on pregnant women.

Ulcerative keratitis can occur. Patients should be monitored for resolution of epethelial defects. The most common ocular adverse reaction was corneal opacity (haze). Other ocular side effects include punctate keratitis, corneal striae, dry eye, corneal epithelium defect, eye pain, light sensitivity, reduced visual acuity, and blurred vision.

These are not all the side effects of the corneal collagen cross-linking treatment. For more information, go to obtain the FDA-approved product labeling.

You are encouraged to report all side effects to the FDA. Visit, or call 1-800-FDA-1088.

*Photrexa® Viscous and Photrexa® are manufactured for Avedro. The KXL® System is manufactured by Avedro. Avedro is a wholly owned subsidiary of Glaukos Corporation.


1. Photrexa [package insert]. Waltham, MA: Glaukos, Inc. 2016