Central Toxic Keratopathy Following Epithelium-Off Corneal Cross-Linking: A Case Series From An External Tertiary Referral Center
Published 2026 - 44th Congress of the ESCRS
Reference: FP02.05 | Type: Free paper | DOI: 10.82333/z0p3-xc09
Authors: Mr Léonard Kollros* 1 , M. Enes Aydemir 2 , Emilio A. Torres-Netto 2 , Mark Hillen 2 , Frank Blaser 3 , Zisis Gkatzioufas 4 , Shady T. Awwad 5 , Farhad Hafezi 2
1ELZA Institute,Zurich,Switzerland;Institute of Optometry,University of Applied Sciences and Arts Northwestern Switzerland (FHNW),Olten,Switzerland;Lorella & Léonard OPTIC,Biel/Bienne,Switzerland;School of Optometry & Vision Sciences,Cardiff University,Cardiff,United Kingdom, 2ELZA Institute,Zurich,Switzerland, 3Department of Ophthalmology,University Hospital Zurich,Zurich,Switzerland, 4Department of Ophthalmology,University Hospital of Basel,Basel,Switzerland, 5Department of Ophthalmology,American University of Beirut Medical Center,Beirut,Lebanon
Purpose
To report clinical and imaging characteristics of central toxic keratopathy (CTK) occurring after standalone epithelium-off (epi-off) corneal cross-linking (CXL).
Setting
Retrospective case series of patients presenting to the ELZA Institute, Zurich, Switzerland, following treatment at an external tertiary referral center.
Methods
Fifteen eyes of 11 patients developed CTK after epi-off CXL performed at the same external tertiary center. Patients later independently sought evaluation at our institution. Clinical assessment included corrected distance visual acuity (CDVA), slit-lamp biomicroscopy, Scheimpflug tomography, anterior segment optical coherence tomography (AS-OCT), Placido-based topography, and confocal microscopy in selected cases. CXL protocols and intraoperative pachymetry data were reviewed when available.
Results
Slit-lamp examination demonstrated dense central stromal scarring in 10 eyes and central haze in 5 eyes. CDVA ranged from 20/20 to 20/200. AS-OCT revealed marked central stromal thinning and dense hyperreflectivity extending through the full stromal thickness, frequently crossing the demarcation line. Scheimpflug imaging confirmed significant thinning (<300 µm in severe cases), altered anterior and posterior curvature, and increased corneal densitometry. Confocal microscopy showed stromal hyperreflectivity consistent with fibrotic remodeling. Several cases involved accelerated protocols or substantial intraoperative corneal thinning after dextran-containing riboflavin application.
Conclusions
Central toxic keratopathy can occur after standalone epi-off CXL and may result in significant stromal thinning, scarring, and long-term visual impairment. Potential contributing factors include excessive UV exposure, intraoperative corneal thinning associated with dextran-based riboflavin, and unregulated riboflavin formulations. Strict UV calibration, intraoperative pachymetry monitoring, and careful selection of riboflavin formulations are essential to minimize risk. Surgeons should remain vigilant for CTK in the postoperative CXL setting.