Eyeworld

by Matt Young EyeWorld Contributing Writer The future of refractive surgery: Nonsurgical? New results from Greece suggest myopia, hyperopia, and astigmatism can be corrected without lasers or incisions R efractive procedures almost always involve lasers or incisions, even at the most non-invasive levels, but change is in our midst. A new procedure called PiXL (photorefractive intrastromal crosslinking, Avedro, Waltham, Mass.) aims to use crosslinking and UV light to alter corneal collagen and thereby cause a refractive change. It's the kind of procedure that makes one wonder whether the refractive surgery of the future is surgery at all. "It's extraordinarily innovative," said Peter Hersh, MD, Cornea & Laser Eye Institute, Hersh Vision Group, Teaneck, N.J. "By focally al- tering the biomechanical properties of the cornea, it is an absolutely novel approach of correcting refrac- tive errors." So far, much of the research into PiXL has been performed in Greece under the watchful eye of A. John Kanellopoulos, MD, director of LaserVision, Athens, Greece. In 50 eyes, Dr. Kanellopoulos has used PiXL to treat mild to moderate myopia, hyperopia, and astigmatism safely, effectively and often leaving the corneal layers— including the epithelium—intact. Innovation with a question Researchers of crosslinking came up with the idea for PiXL with a simple question. "Can we predictably in a normal cornea use collagen crosslinking to change the cornea's refractive power?" Dr. Kanellopoulos said. "In a nutshell, that's what we're able to do with PiXL." Previously, crosslinking has been used notably for treating keratoconus and stabilizing ectasia. Avedro has been pushing the envelop with crosslinking. For example, a procedure called LASIK Xtra uses crosslinking on corneas at risk for ectasia, on hyperopic patients and for high myopes under- going LASIK. Now, Avedro's innovation and promotion of PiXL has "elevated the standard crosslinking procedure to a new platform," Dr. Hersh said. Essentially, the procedure— using riboflavin, UV light, and a few other tools like cornea topography analysis and eye tracking—provides a change in corneal biomechanics to change the corneal optics, rather than use a laser to sculpt tissue. EW International 64 April 2014 A patterned UV energy beam delivers energy to the cornea. "Theoretically, you could write your name with the device," Dr. Kanellopoulos said. That's because patterns can be programmed by clinicians—including everything from butterfly to donut-like shapes. The best modality to deliver the treatments currently is under review. Both "transepithelial" and "epi-off" procedures are being reviewed, according to Dr. Kanellopoulos. C orneal crosslinking is now widely accepted as the treatment of choice to stabilize corneal ectasia. As clinicians have gained experience with crosslinking, it has become evident that selective application may also create a beneficial refractive effect. The earliest generation of crosslinking served to limit the progression of keratoconus. The next step in the evolution of this technique is to reduce the optical aberrations at the same time. An equally exciting concept is the potential that crosslinking may be effective in correcting refractive errors in otherwise normal corneas. Presented here is an up- date on some of the innovative work being done to explore the use of crosslinking for refractive correction. John A. Vukich, MD, international editor These images depict a PiXL toric treatment. 1) The original keratoconus image at the first evaluation of this patient. 2) The pretreatment image documenting progression of the ectasia. 3) The image 6 months flowing PiXL treatment showing the toric treatment. The bottom right image shows the achieved flattening and toric correction. This is a 2.5 D correction of myopia (left before and right 6 months later) with PiXL alone, stable for 6 months. There is no tissue removed here as with traditional laser, and the centration and form of the corneal change is very much "excimer-like." Source (all): A. John Kanellopoulos, MD International outlook

• Cover