Keratoconus treatment has changed much over the past several years. Avedro’s U.S. Food and Drug Administration (FDA) approval of corneal cross-linking has given more patients hope for better vision.
In the past, we could only watch and wait, hoping that keratoconus patients would not progress enough to have significantly reduced vision or require a corneal transplant. Cross-linking has given our patients the opportunity to get on with their lives without fear of reduced quality of life from ectatic disease.
The practice where I work was a clinical trial site for cross-linking, and now our offices perform cross-linking for progressive keratoconus and ectasia on a near-daily basis. I have been fortunate to see a wide range of patients undergo this procedure and to be able to participate in their pre- and postop care.
But with a new paradigm comes new responsibilities for screening, diagnosis, and care. Here are answers to 10 common questions about cross-linking.
1. What are the results of cross-linking?
Cross-linking has been accepted as the standard of care in many countries outside the United States for some time as a safe and effective treatment to stabilize the disease. The international literature suggests that progression of keratoconus is halted in nearly all patients (92 percent to 100 percent) who undergo the procedure,1 and that stabilization of the cornea is maintained over the long term, for at least 10 years after treatment.2
In the United States, three prospective, randomized, controlled trials were conducted, enrolling a total of 335 patients. Among the subjects with progressive keratoconus, maximum keratometry values (Kmax) improved by 1.60 D ± 4.20 D from baseline to one year in the treated group and worsened by 1.00 D ± 5.10 D in the control group. Eyes treated with cross-linking had a mean gain of 5.5 ETDRS letters, with 24 percent gaining two or more lines of corrected distance visual acuity (CDVA).3
2. What is approved in the United States?
The U.S. clinical trials led to approval of cross-linking for the treatment of progressive keratoconus or corneal ectasia following refractive surgery using the Avedro KXL System with photoenhancing solutions Photrexa or Photrexa Viscous. No other cross-linking system is approved for use in the United States, and other systems may be used only as part of a formal investigational new drug (IND) study being conducted in coordination with the FDA.
3. Who should have cross-linking?
All patients with keratoconus should be evaluated to determine whether progression is occurring and whether cross-linking is indicated. As we know, keratoconus often progresses rapidly during puberty and the young adult years. Cross-linking is intended to prevent further progression but may not restore vision that has already been lost. Therefore, it is our responsibility to identify these patients early and educate them regarding the opportunity for cross-linking treatment.
Delaying treatment may result in a greater chance of corneal thinning, scarring, hydrops, and corneal transplant. Progression often slows or stops in patients over age 35 or 40; however, we have seen patients who continue to progress through their 40s and 50s, and therefore it is certainly worth monitoring these patients for progression.
While the corneal stroma must be at least 400 µm thick to proceed with cross-linking, Photrexa is available to thicken the corneal stroma to enable cross-linking in many cases.