Crosslinking meets the previously unmet needs of progressive keratoconus patients and provides an opportunity to increase engagement with optometrists, explain John Berdahl, MD, and George O. Waring IV, MD.
By John Berdahl, MD, and George O. Waring IV, MD; Special to Ophthalmology Times
As surgeons who have been involved with collagen corneal crosslinking (CXL) research over the past decade, we were enthusiastic about the approval in 2016 of the first crosslinking system available in the United States (KXL with Photrexa Viscous and Photrexa riboflavin ophthalmic solutions, Avedro).
CXL provides an opportunity to stop the progressive corneal steepening that can lead to loss of best-corrected visual acuity (BCVA), scarring, contact lens intolerance, and corneal transplant.1 The incidence of keratoconus, as reported in peer-reviewed literature, is about 1 in 2,000.2
With the advent of advanced technology that enables detection of anterior/posterior corneal irregularity-including corneal tomography-clinicians now have the tools to detect keratoconus earlier and with greater sensitivity. Findings from international studies applying this technology suggest the incidence of keratoconus may be greater than previously reported.3
Now that there is an effective treatment that may help stop the disease from progressing, it is much more critical to diagnose these patients before visual function is lost. There are inherent challenges in doing so, as patients in the early stages of keratoconus may be comfortably fit in contact lenses or glasses, and may not present with overt slit lamp findings.
It is incumbent to make sure partners in primary-care optometry are educated about the availability of CXL and the responsibility to refer patients with progressive keratoconus for treatment while they still have the best chance of preserving their vision.
Insurance coverage for CXL is increasingly available. There are patient-assistance programs available to ensure access by providing the photoenhancing riboflavin solutions (Photrexa Viscous or Photrexa) at no charge to low-income uninsured patients and to minimize out-of-pocket expenses for the riboflavin solutions in cases of insurance denials. Coding, reimbursement, and co-management protocols are all still evolving.
For ophthalmologists who already have a strong optometric network, it is easy to inform these existing partners when first performing CXL (or any other new procedure).
In reaching out to potential new partners, it is essential to communicate effective screening criteria, the range of patients that CXL may be able to help, the results obtained in clinical trials, and expectations for follow-up care.
CXL also represents an opportunity for ophthalmologists to differentiate their practices and expand their optometric networks. Unlike laser vision correction, where optometrists may have some ambivalence about referring contact lens or spectacle patients for surgery, CXL is filling an unmet need for keratoconus patients that the optometric community has been highly engaged in and enthusiastic about its development. This is important, because-also unlike LASIK-patients are not going to “self-refer” for keratoconus evaluations unless they already have advanced disease or a well-known family history.
There are still relatively few providers of CXL to meet the needs of patients spread across the country. In rural areas, it is not uncommon for patients to have to travel 4 to 6 hours for a CXL procedure. Developing relationships with potential optometric partners across a wider geographic range for this procedure makes sense and can expand to other referrals in the future.
Given that the diagnosis of keratoconus is primarily a topographic one, it would be ideal for primary eye-care providers (ECPs) to perform high-quality, Placido disc-based topography or corneal tomography on every patient. These diagnostic tools are increasingly being adopted by optometrists, but the reality is many practices do not have the patient volume to support the purchase of advanced imaging devices.
For that reason, we have encouraged primary ECPs in our network to refer any young patient who is not correctible to high-quality, 20/20 or better vision for a keratoconus evaluation if there is no other explanation for decreased BCVA.
Any history of eye rubbing or other risk factors (e.g., atopy or a family history of keratoconus) should heighten suspicion. Referring physicians should know that, for best results, contact lens wearers should be out of soft contact lenses for 1 to 2 weeks and out of rigid lenses for 3 to 4 weeks for every decade of wear prior to CXL evaluation.
Keratoconus is known to be progressive-particularly in the teens and 20s-and clinicians want to diagnose early to minimize any changes in the cornea that could result in loss of visual acuity.
Standards and expectations for keratoconus treatment in patients in their 40s and beyond are still developing.
We encourage referrals of these individuals for evaluation if there has been any progression in the previous 5 years. While progression generally slows or stops in older patients as they become naturally crosslinked, it is a misconception that the disease stops progressing by age 40 in all cases. We have successfully treated patients as old as 65 years.
There will continue to be cases where patients have progressed to the point that CXL cannot be performed. These patients will still need to be managed with specialty contact lenses or penetrating keratoplasty. In the future, we hope to have far fewer patients reach this stage through earlier diagnosis and appropriate treatment.
Post-CXL, the number of visits and type of follow-up care is similar to PRK, so we have found that optometrists who are comfortable and knowledgeable in following PRK patients are well-qualified to follow CXL patients.
Most patients appreciate the opportunity to have appointments closer to home, but it is important to inform patients they have a choice on where they do their follow-up and explain all the costs of that follow-up.
Many cornea specialists will send patients back to their primary ECP before or just following the 1-month visit, after ensuring that the cornea has stabilized and re-epithelialized. We provide optometric partners with written guidelines detailing postoperative medications, the time course of recovery, and expected outcomes
Getting the patient into a well-fitting rigid, hybrid, or scleral contact lens after re-epithelialization is critical in visual rehabilitation, so the optometrist’s contact lens-fitting skills become an important part of providing optimal patient care.
By establishing a system for continuity of care that takes advantage of the skills and expertise of both ophthalmologists and optometrists, CXL can be made more accessible and convenient for patients. CXL provides an opportunity for ophthalmologists not only to perform more procedures, but also to build or strengthen optometric networks.
1. Hersh PS, Stulting RD, Muller D, et al; U.S. Crosslinking Study Group. United States multicenter clinical trial of corneal collagen crosslinking for keratoconus treatment. Ophthalmology 2017 [Epub ahead of print].
2. National Eye Institute (NEI). Facts about The Cornea and Corneal Disease. http://www.nei.nih.gov/health/cornealdisease/#12
3. Godefrooij DA, de Wit GA, Uiterwaal CS, et al. Age-specific incidence and prevalence of keratoconus: A nationwide registration study. Am J Ophthalmol 2017;175:169-72.
John Berdahl, MD
Dr. Berdahl is associate professor of ophthalmology at the University of South Dakota and in practice at Vance Thompson Vision in Sioux Falls, SD. He also serves as medical director of the South Dakota Lions Eye Bank and is a member of the Avedro Medical Advisory Board.
George O. Waring IV, MD
Dr. Waring is assistant professor of ophthalmology at the Medical University of South Carolina (MUSC), director of refractive surgery at MUSC’s Storm Eye Institute, and medical director of MUSC’s Magill Vision Center. He is a member of the Avedro Medical Advisory Board.