Corneal Biomechanical Response Following Collagen Cross-Linking With Rose Bengal–Green Light and Riboflavin-UVA

Abstract

The deformation of UVX-treated corneas was smaller than the RGX-treated corneas. However, the reconstructed corneal mechanical parameters reveal that RGX produced in fact larger stiffening of the treated region (100-μm depth) than UVX (137-μm depth). Rose bengal-green light stiffens the cornea effectively, with shorter treatment times and shallower treated areas. Dynamic air puff deformation imaging coupled with mechanical simulations is a useful tool to characterize corneal biomechanical properties, assess different treatments, and possibly help optimize the treatment protocols.

Medical Applications of Rose Bengal‐ and Riboflavin‐Photosensitized Protein Crosslinking

“…RF-CXL is toxic to stromal cells and corneal nerves although an in vivo confocal microscopy study confirmed that both the cell density and the nerve density returned to baseline levels after 1 year (92). In animal models, RF-CXL increased corneal stiffness as determined by air puff corneal deformation imaging with finite element modeling and by optical coherence elastography (93,94), consistent with previous studies in ex vivo-treated corneas that indicated~2-fold increase in Young's modulus (95)(96)(97)(98)(99). Responses to RF-CXL in rabbit corneas included downregulation of genes for ECM components and upregulation of glycan and proteoglycan glycosylation (100) as well as stromal cell death throughout the anterior and middle stroma (65).…”

Material Properties from Air Puff Corneal Deformation by Numerical Simulations on Model Corneas

“…The average time to highest concavity (HC) was 16.2 ms (± 0.24), while 18.38 ms has been reported for human corneas [35] and 17 ms in rabbits [8]. The shape of the temporal profiles is also different, being very symmetrical and steeper than real corneas in MCs (Fig 9 right), following closely the air puff pressure profile over time.…”

“…In refractive surgery, where corneal thickness is reduced as a result of corneal reshaping to eliminate refractive errors, pre-operative measurements of corneal biomechanics could help identifying patients at risk of iatrogenic ectasia [6]. Individual knowledge of the cornea can help in customizing certain treatments for keratoconus such as intracorneal ring segment implants [7] or to monitor the effectiveness of corneal collagen cross-linking [8]. …”

“…Using temporal and spatial corneal deformation data as input, optimization algorithms allows in principle retrieving corneal biomechanical parameters. In an earlier study, we reported a 2-step optimization procedure to retrieve corneal mechanical properties from corneal deformation data [8]. Simonini et al studied the corneal air puff deformation analytically and numerically [29].…”

Chondroitin Sulfate–Based Biocompatible Crosslinker Restores Corneal Mechanics and Collagen Alignment

“…7 Alternative treatments now aim to avoid UV light exposure to the eye. These include Rose Bengal green light crosslinking 8 and core protein decorin crosslinking that does not require any light exposure. 9 Collagen-based biomaterials also frequently require structural reinforcement through chemical crosslinking.…”