Over the years, we have managed many patients with keratoconus during every stage of the disease, from initial diagnosis to specialty contact lens fitting to end-stage treatment with corneal transplantation. Now that eyecare professionals have an FDA-approved therapeutic treatment for the disease, it’s more important than ever for optometrists to not just diagnose keratoconus but identify signs of progression and refer those patients for treatment.
Corneal collagen cross-linking (CXL) can help slow or prevent progression of keratoconus1,2 and should be considered as part of treatment plans in addition to maintaining good vision with glasses and disposable contact lenses. In addition, the majority of private insurers now cover the FDA-approved epi-off CXL procedure with Photrexa (Avedro).
Related: Best practices for managing crosslinking patients
Patients doing well
Keratoconus is thought to be a progressive ectatic disease in a large percentage of patients. Over time, progressive keratoconus can make contact lens wear increasingly difficult, so the ideal strategy is to intervene early in the disease state.
Early diagnosis and treatment is the best way to preserve a variety of options for vision correction. If the patient is still able to wear glasses or soft disposable lenses, stabilizing the topographic changes with corneal cross-linking could mean that he will continue to succeed in these methods of vision correction.
In addition, early intervention may help patients to avoid the cost and complexity of managing corneal or scleral gas permeable (GP) lenses, which are typically reserved for more complex or advanced cases of keratoconus.
When a patient seems to be doing well in contact lenses, ODs can be tempted to put off a referral for cross-linking. But waiting too long to treat progressive keratoconus increases the chance of decreased best-corrected acuity as the cornea becomes more irregular.3 In some of these cases, the only way to restore acuity is via a corneal transplant.
Related: Collagen corneal cross-linking for keratoconus
Corneal transplant surgery, while still the most successful of all transplant surgeries,4 remains an invasive surgical procedure that has a long healing process and presents many postoperative challenges. It is also associated with a number of potential complications, including the possibility of graft failure.5 Younger patients with progressive keratoconus are more likely to reach a stage requiring a corneal transplant, typically in a more rapid fashion.6
Corneal collagen cross-linking should be a first-line treatment for young patients with progressive keratoconus with the goal of reducing preventable vision loss and the need for corneal transplants.
It is important to understand that CXL alone does not correct the patient’s vision. Although the procedure is commonly associated with some flattening of the corneal curvature as well as post-crosslinking changes in refraction, in our experience patients will generally still need contact lenses or glasses to correct their vision. This maintains optometrists as integral care providers for these patients.
Related: Simplifying the corneal alphabet soup
Corneal irregularity and progression
Topography is an important tool in diagnosing and managing keratoconus. In order to identify the earliest keratoconic changes, the posterior cornea needs to be examined with a more advanced tomography device. There are many uses for a topographer in an optometry office, but it is harder to justify the purchase of a tomographer. If you are suspicious a patient might have an irregular cornea, consider a referral to another colleague (OD or MD) who has access to a tomographer for baseline scans.
Clinicians without access to tomography or topography can still monitor for progression because there are a number of warning signs to be on alert for:
• Frequent prescription changes
• Changes in cylinder
• Inability to refract the patient to 20/20 visual acuity
• Unexpected decrease in visual acuity
• Difficult retinoscopy (scissor reflex)
• Additionally, have a higher degree of suspicion for keratoconus in patients with
- History of eye-rubbing
- Ethnic background with higher rates of the disease (such as Middle Eastern descent)
- Down syndrome
- Atopic disease
One or more of these factors can serve as a diagnostic clue that keratoconus may be an underlying factor.
Related: Pearls for managing keratoconus with CXL
There is no national standard yet for what constitutes “progression” of keratoconus. Many cross-linking and keratoconus research guidelines require a change in refractive cylinder of 1.00 D, steepening of Kmax of 1.00 D, or change in manifest refraction spherical equivalent (MRSE) of at least 0.50 D over a 24-month period.
When progression has not yet been documented, younger patients should be followed more frequently than annually because there is a possibility they can progress rapidly.
Before referring a patient for CXL, set expectations with the patient about the level of care and expertise that each doctor will provide. It’s a good idea to tell patients that they will come back to you for glasses or contact lenses after the procedure and that you may conduct some follow-up exams.
Be aware of what procedures the CXL surgeons in your area are performing. Currently, the only FDA-approved procedure (and therefore the only procedure a patient’s insurance plan will consider covering) is epi-off CXL for patients with progressive keratoconus (or post-refractive surgery ectasia) using the KXL System (Avedro). An ongoing Phase 3 clinical trial is evaluating epi-on CXL (Avedro), but this procedure is still considered investigational.
Related: Keratoconus: cracking the corneal code
When initiating a referral for a CXL evaluation, provide a succinct referral letter that briefly summarizes key findings and the reason for referral. Share what was discussed with the patient so if the surgeon makes a different recommendation, it can be made in a way that is supportive of your relationship.
Ideally, include the last two or three refractions (including cylinder) and topography Kmax readings, if available, to substantiate your findings. This is important for several reasons.
First, evidence of recent progression establishes that the patient will likely benefit from the procedure.
Secondly, it may be necessary for insurance coverage, as discussed above. For the surgical practice, having a year or two of data makes it much easier to advocate for insurance coverage on your patient’s behalf. Without historical data, even when there is high confidence that the patient has a progressive condition that should be treated, it may sometimes be necessary to wait another six months or more to sufficiently document progression. When historical information is relayed to the surgical provider at the outset, it can expedite the process.
Related: Keratoconus, crosslinking, and the changing treatment model
In most cases, surgical practices are happy to return the patient to his trusted primary eyecare provider for ongoing follow-up appointments and contact lens management. Typically, patients will return to the referring doctor at or even before the one-month mark, although this may vary according to the preferences of the referring doctor, surgeon, and/or the patient’s travel distance.
Follow-up care for patients who have undergone CXL is straightforward and can be managed readily by optometrists who are comfortable managing postoperative PRK patients because the healing process is remarkably similar, especially in the early phases. Patients undergoing epi-off CXL are typically seen at Day 1, Days 5 through 7, one month, and then at three or six months. Post-treatment visits are not part of a global period, so they can be billed as office visits.
Related: 7 strategies for fitting keratoconus patients
Patients will be in a bandage contact lens (BCL) for approximately one week. After removal of the BCL, there may be mild superficial punctate keratitis and minimal discomfort. Vision at this stage is usually about the same as preop vision, but it may be a few Snellen lines worse due to epithelial reorganization and mild edema, which are common postoperative findings.
Patients are encouraged to frequently use artificial tears throughout the day and follow the surgeon’s postoperative medication drop regimen, which includes a topical steroid, antibiotic, and sometimes a non-steroidal anti-inflammatory drug (NSAID). Most patients are able to return to soft contact lens wear in two to four weeks and GP lenses around four weeks.
Most studies show a slight flattening of the cornea following the procedure, especially in eyes with steeper corneas.7-9 There may be a small shift in the average keratometry readings within the first six months after CXL. Any changes in refraction after the procedure are likely to be subtle rather than dramatic. It is advisable to wait at least three months before prescribing new contact lenses. Treated patients should continue to be monitored at least annually.
It is important to diagnose keratoconus early and, as soon as there is evidence of progression, to consider treating with corneal collagen epi-off cross-linking. Currently it is the only FDA-approved procedure to stop the progression of the disease. By intervening early, we allow the patient to continue to have multiple options for vision correction.
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About the authorsDr. Hauswirth is director of the Dry Eye Center of Colorado and a consultant to Avedro. He enjoys his time outside clinic watching his son play hockey and spending time with his family hiking and exploring the outdoors.
Dr. Messer received her doctor of optometry degree from Southern California College of Optometry and completed a residency in cornea and specialty contact lenses. She is a member of the Contact Lens Society of America. She has no relevant financial relationships to disclose. Outside the office, Dr. Messer loves to golf, hike and visit family back in her hometown of Dickinson, ND.
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