EyeWorld Asia-Pacific March 2019 Issue

51 March 2019 EWAP REFRACTIVE and no collagen disorganization, epithelial cell and stromal [edema], intrastromal vacuole formation or endothelial cell detachment.” “[A]ll these features are associated with thermal damage to stromal tissue, so we can thus conclude that no such damage occurred,” Wang et al. continued, adding later that confocal microscopy revealed endothelial cell shape and density appeared unchanged between the treated group and controls. “We are very confident in our animal models. They are conclusive,” Dr. Vukelic said, adding that even in samples that weren’t ideal, the method of treatment proved successful every time. At this point, he and coinvestigators are researching how to reduce treatment time from about 35 minutes to 5–6 minutes, Dr. Vukelic said, adding that he hopes to start a clinical trial sometime in the next year. Research on PiXL, which is already available as a refractive treatment in Europe and Asia but not yet approved for use in the U.S., continues to progress as well. A paper session at the 2018 ASCRS•ASOA Annual Meeting included several presentations about photorefractive intrastromal crosslinking. One evaluated the safety and efficacy of PiXL with supplemental oxygen in 40 eyes of patients who were unwilling to have laser vision correction. 2 The mean change in manifest refraction from baseline was 1.18±0.5 D at 3 months postop and UDVA change was logMAR 0.526. According to this research, 78.3% of eyes were UCDVA 20/25 or better at 3 months without significant regression, hyperopic shift, endothelial cell loss, or loss of best corrected visual acuity due to haze. Another paper looked at the safety and efficacy of PiXL with supplemental oxygen with targeted, high-dose, pulsed, accelerated application. At 6 months, the mean change in manifest refraction of the 21 eyes in 11 patients was 1.6 D from baseline; there was a 1.8 D shift in spherical equivalent from baseline. UCVA improved by a mean of four lines, and there was no significant change in endothelial cell density or number of cells. 3 Lim et al. published results in 2017 showing the efficacy and stability of PiXL out to 12 months for treatment of low myopia. 4 EWAP References 1. Wang C, et al. Femtosecond laser crosslinking of the cornea for non-invasive vision correction. Nature Photonics. 2018;12:416–422. 2. Sachdev GS, Ramamurthy S. Photorefractive intrastromal crosslinking for the treatment of low myopia. 2018 ASCRS•ASOA Annual Meeting. 3. Elling Em, Dick HB. Epithelium-on photorefractive intrastromal CXL with supplemental oxygen for low myopic refractive error: six-month results. 2018 ASCRS•ASOA Annual Meeting. 4. Lim WK, et al. Epithelium-on photorefractive intrastromal crosslinking (PiXL) for reduction of low myopia. Clin Ophthalmol. 2017;11:1205–1211. Editors’ note: Dr. Vukelic has no financial interests related to his comments. Contact information Vukelic: sv2147@columbia.edu