Clinical bottom line
Novel corneal cross-linking (CXL) techniques for keratoconus, including customized microneedle-assisted riboflavin delivery and epithelial-on (epi-on) protocols, show promise in enhancing treatment safety, efficacy, and patient comfort. These innovations aim to improve riboflavin penetration while minimizing epithelial disruption, potentially reducing complications and accelerating recovery. Early clinical data suggest comparable biomechanical stabilization to conventional epi-off CXL, but longer-term outcomes and standardized protocols remain under investigation. Clinicians should consider these emerging approaches as adjuncts or alternatives in select patients, balancing efficacy with safety and individual risk profiles (Yang M et al., 2024; Khan et al., 2024; Raiskup et al., 2024).
What the evidence shows
Yang M et al. (2024) describe a customized CXL technique using microneedle-mediated riboflavin delivery, which enhances stromal penetration without full epithelial removal. This method demonstrated improved corneal stiffening effects in early clinical studies, with reduced postoperative discomfort and faster epithelial healing compared to standard protocols.
Khan et al. (2024) review advances in epi-on CXL and combined “CXL-plus” procedures, highlighting that preserving the epithelium reduces infection risk and patient morbidity. Although epi-on CXL traditionally showed lower riboflavin stromal saturation, adjunctive methods such as iontophoresis and enhanced formulations are narrowing this gap, with promising visual and topographic stabilization outcomes.
Raiskup et al. (2024) provide a systematic analysis of transepithelial CXL in progressive keratoconus, reporting stabilization rates comparable to epi-off techniques in mild to moderate disease, though with variable penetration depth and biomechanical effects.
Yang Q et al. (2023) discuss molecular mechanisms underlying CXL, emphasizing that newer delivery methods may optimize collagen cross-linking efficiency by targeting enzymatic and oxidative pathways involved in keratoconus progression.
Alqudah et al. (2024) summarize imaging modalities that support customized treatment planning, enabling tailored CXL protocols based on corneal thickness and disease severity.
Caveats and uncertainty
Most novel CXL techniques have limited long-term follow-up data beyond 2–3 years.
Heterogeneity in protocols, riboflavin formulations, and UVA dosing complicates direct comparisons.
Epi-on methods may be less effective in advanced keratoconus due to limited stromal penetration.
Microneedle-assisted delivery requires specialized equipment and training.
Standardized outcome measures and multicenter trials are needed to validate efficacy and safety.
How this may change practice
Clinicians may increasingly adopt customized and less invasive CXL protocols to improve patient tolerance and reduce complications.
Microneedle-assisted riboflavin delivery could become an option for patients with thinner corneas or higher risk of epithelial healing issues.
Epi-on CXL with enhanced delivery techniques may expand eligibility to patients previously contraindicated for standard CXL.
Integration of advanced imaging can facilitate personalized treatment planning and monitoring.
Ongoing research will refine indications and optimize protocols, potentially shifting the standard of care toward safer, patient-centered approaches.