SECOND-GENERATION “ELZA-SUB400” PROTOCOL FOR CORNEAL CROSS-LINKING IN ULTRATHIN CORNEAS: ONE-YEAR FOLLOW-UP DATA
Published 2026 - 30th ESCRS Winter Meeting
Reference: PO052 | Type: Presented Poster & Poster | DOI: 10.82333/5kp8-fj27
Authors: Farhad Hafezi** 1 , M. Enes Aydemir 1 , Mark Hillen 1 , Léonard Kollros 1 , Nikki Hafezi 1 , Boris Knyazer 2 , Ludmila Nascimento 3 , Luciene Barbosa 4 , Frank Blaser 5 , Emilio A. Torres-Netto 1
1ELZA Institute,Zurich,Switzerland, 2Ophthalmology,Soroka University Medical Center,Beer-Sheva,Israel, 3Eye Bank,UNIFESP - Universidade Federal de São Paulo,São Paulo,Brazil, 4UNIFESP - Universidade Federal de São Paulo,São Paulo,Brazil, 5Ophthalmology,University Hospital Zurich,Zurich,Switzerland
Purpose
The original ELZA-sub400 protocol is an epithelium-off (epi-off) corneal cross-linking (CXL) technique designed to strengthen ultra-thin corneas (~180–≤400 μm). It uses pre-irradiation thinnest-point stromal pachymetry and a validated algorithm to adjust irradiation duration (and therefore total UV fluence) while maintaining a ~70 μm safety margin above the endothelium.
The original ELZA-sub400 protocol employs an irradiation intensity of 3 mW/cm² and a fluence of 5.4 J/cm² for corneas of 400 μm stromal thickness.
The second-generation ELZA-sub400 protocol modifies this approach in two key ways. First, it increases the starting fluence from 5.4 J/cm² to 10 J/cm² at 400 μm stromal thickness. Second, it achieves equivalent safety and efficacy in a shorter, sub-20-minute procedure.
This study presents the one-year follow-up outcomes.
Setting
ELZA Institute, Zurich, Switzerland.
Methods
This study included eyes with progressive keratoconus and corneal thickness below 400 μm treated using the second-generation ELZA-sub400 protocol. UV irradiation intensity was adjusted according to stromal thickness: 9 mW/cm² for corneas with pachymetry ≥330–400 μm and 3 mW/cm² for corneas <330 μm. The fluence was 10 J/cm² at 400 μm and reduced proportionally following our published algorithm.
Outcome measures included keratoconus progression, visual acuity, corneal topography and tomography, and endothelial cell density in a subset of eyes. From baseline to 12 months postoperatively, no significant changes were observed in corrected distance visual acuity (CDVA; P = 0.142), sphere (P = 0.458), or cylinder (P = 0.631). No eyes exhibited endothelial decompensation.
Results
Scheimpflug imaging demonstrated a significant increase in ARC3 mm from baseline at 12 months (mean ± SD: 0.69 ± 0.40 mm; P = 0.048).
No significant differences were observed in minimum corneal thickness (median = −4.0 μm; IQR = −20.0 to 7.0 μm; P = 0.309) or
Kmax (mean ± SD: −0.77 ± 5.10 D; P = 0.418).
ARC3 mm values increased from 5.45 ± 0.95 mm at baseline to 5.75 ± 1.20 mm at 12 months, while mean Kmax decreased from 71.8 ± 13.7 D to 71.0 ± 15.3 D. No significant changes were found in CDVA, sphere, or cylinder. No eyes exhibited endothelial decompensation.
Conclusion
The second-generation ELZA-sub400 protocol provides an individualized, fluence-adjusted CXL approach for ultra-thin corneas.
By individualizing UV irradiation intensity and duration to stromal thickness, it enables safe and effective treatment within a shortened procedure time.
Early one-year data indicate stability in corneal and endothelial parameters, supporting the protocol’s safety and potential efficacy for managing keratoconus in ultra-thin corneas.