Conventional Versus Accelerated Collagen Cross-Linking for Keratoconus

Abstract

: Collagen cross-linking (CXL) is a procedure that primarily aims to increase corneal stiffness. Although used for a variety of conditions, it is most commonly applied to the treatment of keratoconus. Collagen cross-linking involves irradiation of the cornea with ultraviolet A (UVA) irradiation after it has been soaked with riboflavin (vitamin B), a photosensitizer. In conventional treatment, based on the Dresden protocol, a minimum corneal thickness threshold of 400 μm is recommended and UVA (370 nm) irradiation of 3 mW/cm irradiance is applied for 30 min, resulting in a cumulative dose of 5.4 J/cm. Evidence presented in this review shows that conventional CXL stabilizes the vision and corneal topographic parameters in the majority of treated patients, with only a small failure rate. It has a good safety profile with no endothelial cell loss and a small risk of corneal infiltration and infection. To reduce the treatment duration, accelerated protocols of similar efficacy have been sought. In accelerated protocols, UVA irradiation of higher irradiance, typically 9 mW/cm, is applied for a shorter time, typically 10 min. The evidence, limited to small studies with short follow-up, shows that they may also stabilize the vision and the ectasia, with no additional safety concerns highlighted. Randomized controlled studies are, however, required to confirm the encouraging results and noninferiority to conventional treatment.

Assessment of a Novel Corneal-Shaping Device With Simultaneous Corneal Collagen Cross-Linking Using a Porcine Eye Model

“…Although there are a few preliminary reports that suggest accelerated CXL may be comparable to conventional CXL in terms of safety (measured by failure, loss of vision, and endothelial cell loss) and efficacy (measured by improvement in best corrected visual acuity and K values), these are mostly smaller studies with short-term follow-up (6-18 months). 22 Evaluation of CXL efficacy using the stromal demarcation line as a clinical marker has shown a significantly shallower depth of cross-linking in high-intensity, accelerated protocols compared with the conventional treatment, 23,24 which is corroborated by our data showing a greater demarcation line depth in group F (30 minutes, CXL + device) compared with group D (10 minutes, CXL + device). Moreover, our experimental results showing only a significant decrease in corneal curvature with our device after 30 minutes CXL (3 times the conventional CXL dose) but not after 10 minutes UV treatment (accelerated CXL protocol) may hint at limitations to the accelerated protocol, particularly if attempts are to be made to combine CXL with other simultaneous procedures that may require a minimum treatment time (eg, our corneal-shaping device).…”

Riboflavin-induced photo-crosslinking of collagen hydrogel and its application in meniscus tissue engineering

“…Previously, RFpromoted photo-oxidation has been applied to periodontal wound healing using a dental curing light [25]. Furthermore, RF-based collagen crosslinking is currently being used for cornea tissue and cartilage tissue engineering [26,27]. Our results support the notion that collagenous biomaterials can be rapidly photo-crosslinked when exposed to UV light in the presence of RF.…”

Knockdown of collagen α‑1(III) inhibits glioma cell proliferation and migration and is regulated by miR128‑3p

“…Additionally, silencing COL3A1 expression in vitro inhibited glioma cell proliferation and migration. This might be closely related to the following three primary functions of collagen in brain tumors: to act as: i) a scaffold and provide sites for cell adhesion; ii) a reservoir for extracellular matrix proteins, proteoglycans and growth factors; and iii) a ligand to activate signal transduction networks required for tumor growth, differentiation and invasion (25)(26)(27)(28)(29). Although the underlying mechanism for these effects still needs to be studied, our results gave a hint on the role of COL3A1 in collagen and brain tumor.…”