Central Toxic Keratopathy After Epithelium-Off Corneal Cross-Linking For Keratoconus: A Series Of 17 Eyes Treated At The Same Hospital

To investigate the occurrence of central toxic keratopathy (CTK) in patients after epi-off corneal cross-linking (CXL), a rare but serious complication characterized by sudden cloudiness in the cornea that can affect vision. CTK may develop after procedures like CXL due to changes in the cornea's structure and cell loss. This study focuses on understanding how often CTK occurs after epi-off CXL, what contributes to its development, and its effects on patients' vision, aiming to improve treatment safety and outcomes.

This study was conducted at the ELZA Institute, Dietikon, Switzerland, focusing on patients who previously received epi-off CXL elsewhere, all at the same hospital.

In this case series, 17 patients who developed central toxic keratopathy (CTK) post-epi-off CXL at the same hospital, from 2011-2016 were reviewed. ^After presentation to our clinic (2016-2023), patients underwent comprehensive ophthalmic assessments, including CDVA, manifest refraction, and AS-OCT (CSO Italia) for high-resolution corneal imaging. All cases received detailed evaluations with anterior curvature maps, corneal and total wavefront analysis, analysis of point spread function, image convolution analysis, and Pentacam densitometry.

AS-OCT imaging revealed significant scar tissue in 10 eyes and deep stromal haze in 7, indicating varied severity of CTK complications post-epi-off CXL. Case examples: 1) A 33-year-old with central dome-shaped opacity and corneal stromal thinning, resulting in decreased CDVA. 2) A 34-year-old male patient exhibited central corneal melting with increased density, leading to reduced visual acuity. 3) A 32-year-old female showed haze and hyperreflectivity on AS-OCT, correlating with decreased CDVA. These cases illustrate the profound impact of CTK on visual outcomes, emphasizing the risk associated with the procedure.

The aetiology of CTK is uncertain, but UV exposure, choice of the riboflavin solution containing dextrane as a carrier and certain intraoperative triggers appear to be implicated. These cases of CTK following CXL suggest that there may be potential issues with UV overexposure and the usage of riboflavin with dextran as a vehicle. Despite CXL's well-established safety and efficacy profile, CTK can remains a serious potential risk of the procedure. This underscores the need for continued research into safer alternatives, such as epi-on CXL, and reinforces the importance of precise procedural controls to enhance patient safety and treatment outcomes.