March 2014 Online Photo Diagnosis

By Luciano Bastos

This image shows a resultant circular, ring-shaped mark on a keratoconus patient’s cornea following the Keraflex KXL Accelerated Corneal Cross-Linking (CXL) procedure, performed with Avedro’s Vedera System. This novel procedure to treat keratoconus is still in clinical trials² and is not commercially available except in a few countries.

The Keraflex Microwave System refractive correction procedure is a microwave-based, non-incisional ophthalmic procedure for flattening the cornea without the removal of tissue. The treatment takes less than a second, and it is enhanced through a subsequent treatment of CXL using Avedro’s KXL System for accelerated cross-linking^{1, 3, 4}.

A Case of Keratoconus

This patient from Brazil underwent the Keraflex KXL procedure in 2012 in Turkey, as it was not available in Brazil, the United States, or the United Kingdom at the time. He had traveled to Turkey specifically to get the procedure with the hope of eliminating his bilateral keratoconus and obtaining a less irregular corneal topography through the accelerated CXL. He was very optimistic about the possible prognosis and the thought of eliminating his condition.

The patient was a 32-year-old policeman who had mild-to-moderate keratoconus prior to the procedure. His previous experiences with GP corneal contact lenses were not successful, and he wanted to undergo this procedure to help him achieve better visual acuity and to avoid a more invasive procedure, such as penetrating keratoplasty.

Post-Procedure Initial Difficulties

In the first six to eight months after the procedure, the patient complained of vision fluctuation and reported that his vision was worse than it had been before the procedure. At the time of his first visit with us, we observed that both eyes had a circular mark from the procedure. This mark was better observed after fluorescein instillation (Figure 1). The mark probably results when the Keraflex procedure cools the area adjacent to where the microwave pulse is applied. Figure 2 shows his corneal biomicroscopy. His topography was very irregular, although it seemed that there was a significant flattening effect.

Figure 1. Circular ring observed after fluorescein instillation.

Figure 2. Corneal biomicroscopy of the patient’s cornea (identical for both eyes).

Figure 3 show his corneal topography images from just prior to the procedure. We observed that after the procedure, his corneal topography changed over approximately 10 to 12 months before it stabilized. It is important to note that the flattening that we initially observed did not remain, and ectasia was evident in recent Pentacam (Oculus) anterior segment tomography images (Figure 4). Figure 5 shows the Pentacam Scheimpflug and three-dimensional (3D) modeling images, which were also taken 18 months after the procedure.

Figure 3. Patient’s corneal topography prior to the treatment.

Figure 4. Pentacam images 18 months after the procedure.

Figure 5. The Pentacam Scheimpflug and 3D modeling images also show the circular ring mark at the paracentral axis of the cornea.

The visual fluctuation that the patient experienced may be due to instability of the cornea’s biomechanical resistance and the viscoelastic properties. We did not investigate this, as our focus was to restore the best visual correction to the patient.

Contact Lens Fitting

We attempted a contact lens fitting in March 2013. We observed that the patient had a tear breakup time of only 6 to 7 seconds, which is relatively low for his age. We discussed the possibility of scleral lens fitting and diagnostically fit both scleral and GP lenses. We ultimately fit the patient with the Ultracone design (Ultralentes) with a nice result (Figure 6).

Figure 6. Final fit with the Ultracone design for keratoconus.

In subsequent follow-up visits, the patient reported good vision and less visual fluctuation. He wears his lenses for 10 to 12 hours a day, instilling lubricants when he feels dryness. This may have been the first Brazilian patient to undergo this type of procedure, so it was a unique fitting and experience.

The Keraflex technology seems to be a promising procedure, but our experience indicates it may need to be improved to avoid the visual fluctuation that frustrated this patient. After 18 months, he reported less fluctuation, but a light corneal haze remains present.