Phototherapeutic Keratectomy: Science and Art.

Abstract

To describe, with videos, the principles of excimer laser phototherapeutic keratectomy (PTK) for the treatment of corneal scars, corneal surface irregularity, and recurrent corneal erosions. Depending on the pathology in a treated cornea, the epithelium is removed either by transepithelial PTK ablation with the excimer laser or thorough scraping with a scalpel blade. Stromal PTK can be performed with or without photorefractive keratectomy (PRK), depending on the refractive status of both eyes. Residual surface irregularity is treated with masking-smoothing PTK. Typically, 0.02% mitomycin C treatment is applied for 30 seconds to corneas treated with PTK for scars and surface irregularity. Transepithelial PTK with masking-smoothing typically improves corrected distance visual acuity in the eye even if the entire stromal opacity cannot be removed and can be used to debulk surface irregularity to facilitate subsequent therapeutic customized wavefront-guided or optical coherence tomography-guided PTK or PRK. PTK for recurrent erosion is performed after thorough mechanical epithelial debridement of redundant epithelial basement membrane (EBM) with a scalpel and should only include a dusting of excimer laser to remove residual EBM without inducing central irregular astigmatism or damaging limbal tissues. Meta-analyses are provided for PTK treatment for corneal scars, corneal dystrophies, and recurrent corneal erosions. Excimer laser PTK is a highly effective treatment for superficial corneal scars, central corneal irregular astigmatism, and recurrent corneal erosions unresponsive to medical treatment or mechanical epithelial debridement alone. [J Refract Surg. 2017;33(3):203-210.].