NEWS & OPINION 58 EWAP SEPTEMBER 2022 by Neal Patel, MD, and Nandini Venkateswaran, MD Contact information Lorch: Alice_Lorch@meei.harvard.edu Patel: neal_patel@meei.harvard.edu Venkateswaran: nandini_venkateswaran@meei.harvard. edu Review of ‘Comparison of contact lens-assisted and transepithelial corneal crosslinking with standard epithelium-off crosslinking for progressive keratoconus: 24-month clinic results’ Over the last decade, corneal crosslinking (CXL) has rapidly grown in popularity among ophthalmologists for its ability to halt the progression of keratoconus and other corneal ectasias. The Dresden protocol is widely regarded as the standard for CXL, against which other protocols for CXL are compared.1 In this standard epithelium-off (epi-off) techniµue, the central n mm of corneal epithelium is removed before saturation of the corneal stroma with riboyavin and subseµuent treatment with UV-A.2 Removing the epithelium has been shown to allow improved absorption of riboyavin and 1V-A penetration into the corneal stroma.3–5 owever, this techniµue is relatively contraindicated in corneas with pachymetry less then 400 microns after epithelium removal due to risk of endothelial damage by UV-A.6 Additionally, epithelial debridement is associated with complications including increased postoperative pain, corneal haze, and risk of infective keratitis.7 Several alternative techniµues have been described to overcome these limitations of epi-off techniµues and improve the safety of CXL in thinner corneas. Among these techniµues are transepithelial CXL (TECXL) and contact lensassisted CXL (CACXL). TECXL avoids epithelial removal and uses a riboyavin solution containing substances that enhance epithelial penetration.8 This techniµue has been demonstrated to have improved postoperative comfort and reduced corneal haze, however, the efficacy of this techniµue as compared to standard epi-off 8L has been µuestioned.9–11 CACXL involves the use of a riboyavin-soaked 1V barrier- free contact lens placed on a deepithelialized cornea to compensate for reduced corneal thickness and prevent damaging levels of UV-A from reaching the endothelium.12 In this study, the authors retrospectively compared outcomes of TECXL and A 8L techniµues along with standard epi-off CXL in patients with progressive keratoconus. Design and methods This retrospective, single-center study included 58 eyes that underwent CXL for progressive keratoconus at the Cornea Services of Advanced Eye Center in Chandigarh, India, between January 2013 and June 2018. Patients were included if they had keratoconus with evidence of progression, as defined by consistent changes in keratometry, refraction, and/or pachymetry on two consecutive visits and had post-procedure follow-up of at least 2 years. Keratometry and corneal thickness measurements were performed with Scheimpyug imaging on Pentacam (Oculus). The standard epi-off techniµue was used only in eyes with minimal corneal thickness (MCT) of at least 450 microns as measured with an intact epithelium. TECXL and CACXL were used for patients with MCT between 350 microns and 450 microns. There were no predetermined criteria or systematic approach to select among epi-off, TECXL, and A 8L techniµues in patients, except that TECXL was initially avoided in patients under the age of 18 years due to concern of possible reduced efficacy in the pediatric population.13 All patients were examined on the first and fifth postoperative day, 1 month, 3 months, and 6 months, followed by every È months. Efficacy of each 8L techniµue was udged based on the ability of the procedure to halt or stabilize ectasia. Progression, stabilization, or regression of ectasia was determined by change in maximum keratometry (Kmax) at the 2-year follow-up as compared to baseline, with This article originally appeared in the June 2022 issue of EyeWorld. It has been slightly modified and appears here with permission from the ASCRS Ophthalmic Services Corp. Alice Lorch, MD Residency Program Director Massachusetts Eye and Ear Boston, Massachusetts Neal Patel, MD Resident Massachusetts Eye and Ear Boston, Massachusetts Nandini Venkateswaran, MD Cornea, Cataract, and Refractive Surgeon Massachusetts Eye and Ear, Waltham Waltham, Massachusetts
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