BARCELONA, Spain -- One-year results with the second-generation ELZA-sub400 protocol for corneal cross-linking showed efficacy in halting keratoconus progression in ultrathin corneas, according to a study presented here.
"The second-generation ELZA-sub400 protocol presents an updated accelerated approach to managing progressive keratoconus in patients with ultrathin corneas. One-year follow-up data look promising," Emilio Torres-Netto, MD, PhD, said at the European Society of Cataract and Refractive Surgeons meeting.
The study included 29 eyes with pre-irradiation corneal thickness ranging from 246 µm to 399 µm. No significant changes in maximum keratometry, spherical power and cylindrical power in both visual acuity and corneal topographical parameters were observed compared with baseline values. Endothelial cell density counts remained stable, suggesting that the higher ultraviolet (UV) fluences had no adverse effects on deeper corneal layers.
The original ELZA-sub400 protocol was designed to strengthen corneas with a thickness between 180 µm and 400 µm using epithelium-off cross-linking. A validated algorithm adjusted UV irradiation intensity and duration based on pre-irradiation thinnest point stromal pachymetry, maintaining a 70 µm uncross-linked safety margin at the base of the stroma to protect the corneal endothelium from UV-induced damage. This technique utilized an irradiation intensity of 3 mW/cm², delivering a fluence of 5.4 J/cm² at 400 µm stromal thickness.
In the updated second-generation protocol, two modifications were introduced to reduce treatment time while maintaining similar efficacy to the first-generation protocol. UV irradiation intensity was tailored to corneal thickness, with 9 mW/cm² applied to corneas measuring between 330 µm and 400 µm and 3 mW/cm² for corneas thinner than 330 µm. At 400 µm stromal thickness, the fluence was set at 10 J/cm², which was progressively reduced with respect to the thinnest point stromal thickness according to a previously published algorithm.
"The ELZA-sub400 protocol builds on the first-generation protocol by not only accelerating the procedure but also applying higher depth-adjusted UV fluences to ensure no cross-linking efficacy is lost through the acceleration of UV fluence delivery," Torres-Netto said.