FIGURE. Drops of riboflavin applied to a patient’s cornea while she undergoes corneal collagen cross-linking
Until recently, there were few treatment options for keratoconus, a condition characterized by the progressive thinning and bulging of the cornea that leads to myopia and irregular astigmatism. To treat the condition, patients were given increasingly stronger prescriptions for corrective lenses, hard contact lenses, and possibly intrastromal corneal ring segments for support. Eventually, some would require a corneal transplant.
In spring 2016, the US Food and Drug Administration approved collagen cross-linking to treat keratoconus. The treatment involves using riboflavin plus ultraviolet light to strengthen the collagen of the cornea (Figure). Although it is not curative, the treatment halts disease progression, helping patients avoid a corneal transplant and its associated risks. The Duke Eye Center is 1 of only a few centers in the southeastern United States to offer the treatment.
“As a corneal specialist, I routinely see patients in their 30s who are getting corneal transplants,” says Duke corneal specialist Preeya K. Gupta, MD, who uses the treatment. “My hope is that we do fewer and fewer transplants for keratoconus because patients will have received cross-linking earlier in their disease course so it never progresses to the stage at which they need a corneal transplant.”
Gupta says that a secondary benefit of the treatment is that it may provide some visual improvement for patients: Studies show it can flatten the cornea by about 1.5 to 2 diopters, on average. However, she cautions that the change is not likely to be dramatic, especially in patients with more advanced disease, and she says she’s careful to set reasonable expectations for patients. In the future, Gupta expects it will be possible to pair cross-linking with refractive surgeries to not only halt keratoconus but also further improve visual acuity.
Ideal candidates for collagen cross-linking are younger because the earlier a patient develops the disease, the more years they have for the disease to progress and worsen. In addition, the progress of keratoconus tends to slow with age, so older patients do not tend to experience as much benefit. The exception to this would be a patient who is older but shows documented disease progression—in such a case, it might be appropriate to pursue cross-linking.
Gupta notes that the new treatment is an important step forward for the field: “A lot of times, even for a patient with mild disease, people will say, ‘Well, there’s not much we can do,’ but I think this treatment has the potential to change the paradigm of treatment. We now have a treatment that can stop disease progression, so it’s a huge benefit to patients to be diagnosed and treated early.”