Second-generation ELZA-sub400 protocol: Individualized high-fluence cross-linking for ultra-thin keratoconus corneas

Hafezi, Farhad, Akcan, Rüstü Emre, Kling, Sabine, Kollros, Léonard, Depczyńska, Michalina, Awwad, Shady, Knyazer, Boris, Hafezi, Nikki, Blaser, Frank, Hillen, Mark and Torres-Netto, Emilio A. 2026. Second-generation ELZA-sub400 protocol: Individualized high-fluence cross-linking for ultra-thin keratoconus corneas. American Journal of Ophthalmology 290 , pp. 318-328. 10.1016/j.ajo.2026.06.034

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Abstract

PURPOSE To evaluate the safety and efficacy of a second-generation individualized corneal cross-linking (CXL) protocol (ELZA-sub400) using high-fluence UV-A irradiation in ultrathin ectatic corneas. DESIGN Retrospective, single-centre, consecutive interventional case series. METHODS Twenty-nine eyes of 24 patients with progressive keratoconus or post-LASIK ectasia and a post-soak intraoperative thinnest stromal thickness <400 µm were included. After epithelial removal and riboflavin soaking, continuous UV-A irradiation (365 nm) at 3 or 9 mW/cm² was delivered with total fluence titrated up to 10 J/cm² based on intraoperative ultrasound pachymetry and a previously published nomogram targeting an uncross-linked stromal margin of approximately 70 µm above the endothelium. Outcomes were assessed at baseline and up to 12 months using corrected distance visual acuity (CDVA) and corneal parameters measured using Scheimpflug tomography and anterior segment OCT (AS-OCT) with Placido-based topography. The main outcome measure was the proportion of eyes without progression at 12 months, defined as <1.0 D increase in maximum keratometry (Kmax). Secondary outcomes included changes in CDVA, refraction, Kmax, stromal thickness, demarcation line depth, densitometry, and safety parameters. RESULTS At 12 months, 22/29 eyes (76%; 95% CI, 57.9%–87.8%) met the non-progression criterion. Mean change in Kmax was −0.77 ± 5.10 D (95% CI, −2.71 to 1.17; p=0.418). Mean demarcation line–to–anterior stroma distance was 205 ± 64 µm (95% CI, 180.7–229.3), and demarcation line–to–endothelium distance was 64 µm (IQR, 49–152). All demarcation lines remained within the stromal layer; 15/29 eyes (51.7%) had a demarcation line located ≤70 µm from the endothelium. Median CDVA changed from 0.10 to 0.32 logMAR (p=0.142). Minimum stromal thickness showed a median change of 4.0 µm (p=0.309). No significant change was observed in densitometry, and no eye developed deep stromal haze or endothelial decompensation. CONCLUSIONS Second-generation ELZA-sub400 CXL halted ectasia progression in 76% of ultrathin corneas at 12 months and was associated with an acceptable short-term safety profile, including stromal-confined demarcation line formation and no observed endothelial decompensation. The numerical decline in spectacle CDVA observed in this severely affected cohort did not reach statistical significance but is clinically important and warrants confirmation in larger prospective studies.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Optometry and Vision Sciences
Additional Information:	License information from Publisher: LICENSE 1: Title: This article is under embargo with an end date yet to be finalised.
Publisher:	Elsevier
ISSN:	0002-9394
Date of Acceptance:	19 June 2026
Last Modified:	04 Aug 2026 13:11
URI:	https://orca.cardiff.ac.uk/id/eprint/187961

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