EyeWorld Asia-Pacific December 2016 Issue

December 2016 44 EWAP refractive Predictable refractive outcomes: The future of keratoconus treatment by Liz Hillman EyeWorld Staff Writer Experts say PiXL procedure is promising but still has ‘a long way to go’ “ E xtremely interesting and positive.” That’s how Roberto Pinelli, MD , founder of the Switzerland Eye Research Institute, Lugano, Switzerland, described the current state of crosslinking in ophthalmology. While excitement certainly continues after the U.S. Food and Drug Administration (FDA) approval of Photrexa and Photrexa Viscous (Avedro, Waltham, Massachusetts) as well as the company’s KXL System for treatment of progressive keratoconus earlier this year, the riboflavinUV light procedure— first described decades ago and available internationally for years—is not remaining stagnant in its technology or technique. There have been modifications as well as new indications for the procedure in recent years. Conventional crosslinking stabilizes and strengthens the cornea for progressive keratoconus and ectasia patients, but some physicians have been working with the technology and refining the technique to obtain predictable refractive outcomes as well. “We know that crosslinking for keratoconus is a very good treatment,” Anders Behndig, MD , Umeå University, Sweden, said at the 2016 ASCRS•ASOA Symposium & Congress. “We do the same treatment protocol in all cases of keratoconus though, which from a refractive standpoint might not be so good. “Of course, the main purpose of the treatment is to halt the disease, which [crosslinking] does, but it would be nice to control the refractive effects of the treatments, too,” Dr. Behndig continued. For both refractive effects and corneal stability, crosslinking is now regularly coupled with A 45-year-old male with 2 D myopia received epi-on PiXL treatment. His preop meas- urements are on the left, postop in the middle, and the difference between the two on the right. These are the difference maps (preop top right, postop bottom right, and preop minus postop left) documenting excimer-like correction with crosslinking alone in a pseu- dophakic female who achieved 2.5 D of myopic correction with PiXL treatment. continued on page 46 topography-guided photorefractive keratectomy (PRK), intrastromal rings, and even LASIK. Dr. Behndig thinks there could be another option for predictable refractive outcomes in keratoconus treatment: photorefractive intrastromal crosslinking (PiXL, Avedro). This topography-guided crosslinking, which has been available internationally for the last few years, is marketed by Avedro as the “next revolution in refractive correction” in low myopic or postcataract patients. Dr. Behndig spoke at the ASCRS•ASOA Symposium & Congress about PiXL in the context of providing customized, refractive keratoconus treatment. PiXL, which Avedro describes as using “precise, patterned, topography-guided accelerated crosslinking,” involves real-time eye tracking and a higher UVA power. The UV light is customized and directed in a specific pattern based on the patient’s topography to flatten the cornea where most needed. According to his own research involving 12 months worth of data on 25+25 eyes, Dr. Behndig said he found that PiXL offered a significant refractive advantage over conventional crosslinking in keratoconus. He admitted, however, that the difference was not huge. “The effects are promising so far. Of course, the method will need further fine tuning, but my impression is that this procedure has the potential to become valuable in treating keratoconus in the future.” Dr. Pinelli, who patented the transepithelial riboflavin solution ParaCel, now owned by Avedro, has had a similar experience with the technology. “Obviously the customization based on topography is theoretically interesting, but we have no difference in our cases