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R. R. Krueger, H. Sheardown, X. Duan, S. Herekar; Photochemical Corneal Augmentation: Crosslinking Clear Liquid Collagen for Corneal Repair and Refractive Correction. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5363.
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To introduce a novel photochemical method for augmenting the shape and thickness of the cornea in-situ.
Clear liquid collagen (both porcine & recombinant human), at varying concentrations (5 to 15% weight/volume), was mixed with a PriaVision customized crosslinker at 1:500 to 5:100 dilution ranges, and exposed to ~370nm UVA light at various intensities (6 to 30 mW/cm2) and exposure times (1 to 15 minutes) to determine the optimal augmentation parameters. Multiple ex vivo enucleated bovine and cadaver eyes were tested by molding various thicknesses (100um, 200um, 300 um) of the augmented collagen layer onto the de-epithelialized cornea. Additionally, 5 rabbits were augmented unilaterally beneath UVA transmissive contact lenses with an injection of collagen/XL mixture, and UVA irradiated for up to 15 minutes. The rabbits were examined, tested and followed for two months.
The crosslinked collagen solidifies to demonstrate optically clear gelation and biomechanical adherence properties in vitro. The optimal parameters for augmentation, based on preliminary ex-vivo globe experiments, are outlined in the Table below. The optical clarity, refractive index, diffusion permeability, mechanical suture strength and rheometric data were compared to native corneal stromal tissue and found to be equivalent or better. Preliminary rabbit results demonstrate rapid re-epithelialization (<7 days postop), uniformity of hydration, good tear film quality & volume, stable IOP & thickness, and neuronal regrowth based on esthesiometry by 4 to 6 weeks postop.
Photochemical corneal collagen augmentation demonstrates superior biocompatibility, as well as optical, biomechanical and adhesive properties, making it suitable for clinical use. We believe it has the potential to reconstruct and strengthen diseased and ulcerated corneas, as well as provide a substrate for refractive onlay/ inlay procedures and lamellar transplantation.
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