Current status of accelerated corneal cross-linking

Abstract

Corneal cross-linking with riboflavin is a technique to stabilize or reduce corneal ectasia, in diseases such as keratoconus and post-laser-assisted in situ keratomileusis (LASIK) ectasia. There is an interest by patient as well as clinicians to reduce the overall treatment time. Especially, the introduction of corneal cross-linking in combination with corneal laser surgery demands a shorter treatment time to assure a sufficient patient flow. The principles and techniques of accelerated corneal cross-linking is discussed.

Current Protocols of Corneal Collagen Cross-Linking: Visual, Refractive, and Tomographic Outcomes

“…Hence, a reduction of the treatment time by simply increasing the intensity might not be efficacious in stopping the progression of corneal ectasia thereby leading to higher failure rates. 16 A demarcation line noticed after CXL which denotes the area of keratocyte apoptosis caused by riboflavin penetration gives an indirect measure of the depth and effectiveness of this procedure. 17,18 Pahuja N et al, in their study on the depth of penetration of riboflavin using a microscope-integrated real time spectral domain optical coherence tomography in keratoconus patients undergoing ACXL with and without epithelium debridement have shown adequate penetration of riboflavin into the anterior stroma at the end of procedure in both groups.…”

In Vivo Confocal Microscopy after Corneal Collagen Crosslinking

“…14 conventional CXL were generally not detectable after TE-CXL treatments, as confirmed by IVCM and spectral domain corneal OCT. [15][16][17][18]29,75 According to IVCM findings, biomechanical studies, and clinical evidence, TE-CXL as classically conceived with 3mW/cm 2 UV-A power associated with "enhanced" riboflavin solutions can be considered limited and inferior to other methods. "Supporters" of TE-CXL are directing their efforts to ionthophoretic electric-assisted delivery of riboflavin into the corneal stroma via an "apparently" intact epithelium combined with ACXL at 9 mW/cm 2 of UV-A power.…”

“…No endothelial damage was observed in terms of morphology and cell count after ACXL. [15][16][17][18]29,75 IVCM is useful not only for assessing the safety and efficacy of conventional, transepithelial and accelerated cross-linking but also for elucidating the mechanisms by which cross-linking works. There is a reasonable correlation between confocal aspects and tomographic data that helps to explain the functional and biomechanical effect of cross-linking.…”

“…On the other hand, the Bunsen-Roscoe's law of reciprocity that was established for photochemical reactions paved the way for ACXL protocols, showing it was safe for endothelium and posterior ocular structures. ACXL penetration reaches the anterior part of the stroma, stiffening the cornea between 150 and 200 µm, with relative differences between the different protocols.17,18,26,30 …”

Riboflavin photo­protection with cross-linking effect in photorefractive ablation of the cornea

“…Такой подход, на наш взгляд, имеет преимущества перед методикой ускоренного кросс-линкинга, при которой рекомендуется применение 0,25% раствора рибофлавина, а сама методика его выполнения имеет различные модификации [12,13]. Это обусловлено прежде всего тем, что исклю-чается дополнительная УФ-нагрузка на роговицу, которая уже подверглась оксидативному стрессу в процессе фотоабляции.…”