Dr.Gitansha Sachdev, Dr.Shreyas Ramamurthy
ABSTRACT
Purpose: To evaluate the safety and efficacy of photorefractive intrastromal crosslinking (PiXL) for the treatment of low myopia using epithelium-on approach with supplemental oxygen.
Setting: The Eye Foundation, Coimbatore, India
Design: Prospective interventional case series
Methods: Myopic patients with healthy non-ectatic corneas underwent photorefractive intrastromal crosslinking (PiXL) using the Mosaic system. Ultraviolet-A (UV-A) irradiation of 365nm wavelength was delivered as a central 4 millimeter beam in an accelerated (30mw/cm2) pulsed (1 second on-1 second off) approach to provide a total fluence of 15J/cm2. Supplemental oxygen (concentration greater than 95%) was provided to increase the efficacy of the epithelium-on approach. Efficacy was determined by improvement in manifest refractive spherical equivalent (MRSE) and keratometric flattening. Safety was determined by loss of lines of best corrected visual acuity (BDVA), endothelial cell loss and adverse events.
Results: Fifty eyes of 26 patients with a mean age of 22.73 ± 3.74 years were included in the study. A significant improvement in UDVA from baseline (Log MAR 0.63 ± 0.25) was noted at 3 (0.08 ± 0.15) and 6 months (0.13 ± 0.18) follow-up visits(p<0.001). Significant keratometric flattening from baseline was noted at all follow-up visits (p<0.001). No significant endothelial cell loss or adverse effect were noted. A significant correlation was noted between the change in MRSE and preoperative corneal biomechanics (deformation amplitude ratio).
Conclusion: Transepithelial PiXL with supplemental oxygen is a safe and effective approach for correction of low myopia. The change in MRSE and keratometric flattening was greater in comparison to earlier protocols, including the epithelium off approach.
Key Words: Photorefractive Intrastromal Crosslinking; PiXL; myopia; transepithelial CXL
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