Collagen cross-linkage: A comprehensive review and directions for future research
ABSTRACT Individuals with keratoconus form a significant proportion of patients for a practitioner specialising in corneal diseases. Yet it is a disease where the pathogenesis is poorly understood, and until recently, there has been no treatment apart from transplantation that could be offered that was curative or even capable of slowing the progression of the disease. Collagen cross-linking treatment using riboflavin and UV light has been developed to address this need, and the initial results are promising. The purpose of this review is to critically evaluate this treatment in light of the scientific basis for cross-linking, to highlight the strengths and limitations of the evidence in terms of efficacy and long-term safety, and finally to identify areas for future research in this area with a significant potential to change the way we treat our keratoconus patients. In addition, we hope that our unbiased review for the first time would bring together, in a concise fashion, scientific information for a practitioner contemplating on offering this treatment and to help inform their patients of its potential risks and benefits.
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ABSTRACT: The last 2 years has seen a marked increase in the prominence of corneal collagen cross-linking as a treatment strategy for progressive keratoconus. This interest has arisen from a body of laboratory evidence documenting the biomechanical and cellular changes induced by cross-linking. The findings of this research provide a plausible rationale for its use in keratoconus to retard the progression of this common disease. The rapidly growing number of clinical reports suggests, not only a consistent stabilizing effect of cross-linking, but that a variable improvement in corneal shape and visual function may also occur in some patients. However, the marked variation in the clinical course of keratoconus, together with the challenges of accurately evaluating refractive error, visual acuity and even corneal shape in this condition, demands further evidence from randomized controlled clinical trials. The aim of this review is to summarize the theoretical basis and risks of corneal collagen cross-linking, along with the available evidence for its use in keratoconus and other corneal disease states.Clinical and Experimental Ophthalmology 03/2010; 38(2):141-53. DOI:10.1111/j.1442-9071.2010.02228.x · 1.95 Impact Factor
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ABSTRACT: To assess the safety, efficacy, stability, and predictability of collagen copolymer toric phakic intraocular lens (pIOL) implantation to correct myopia and astigmatism in eyes with keratoconus. Fernández-Vega Ophthalmological Institute, Oviedo, Spain. This prospective study comprised keratoconic eyes that had implantation of a toric Intraocular Collamer Lens. Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, and postoperative complications were evaluated 1, 3, 6, and 12 months postoperatively. Preoperatively, the mean spherical equivalent in the 30 eyes (21 patients) was -5.38 diopters (D) +/- 3.26 (SD) (range -13.50 to -0.63 D) and the mean cylinder, -3.48 +/- 1.24 D (range -1.75 to -6.00 D). At 12 months, 86.7% of the eyes were within +/-0.50 D of the attempted refraction and all eyes were within +/-1.00 D. For the astigmatic components J0 and J45, 83.3% of eyes and 86.7% of eyes, respectively, were within +/-0.50 D. The mean Snellen UDVA was 0.81 +/- 0.20 and the mean CDVA, 0.83 +/- 0.18; CDVA was 20/40 or better in 29 eyes 96.7% of eyes and 20/25 or better in 22 eyes (73.3%). No eyes lost more than 2 lines of CDVA; 29 eyes (96.7%) maintained or gained 1 or more lines. The efficacy index was 1.07 and the safety index, 1.16. There were no complications or adverse events. The results confirm that toric ICL implantation is a predictable, effective procedure to correct ametropia in eyes with keratoconus. Predictability and stability were achieved early and remained fairly stable up to 12 months.Journal of Cataract and Refractive Surgery 06/2010; 36(6):906-16. DOI:10.1016/j.jcrs.2009.11.032 · 2.55 Impact Factor
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ABSTRACT: The ability to clearly observe one's environment in the visible spectrum provides a tremendous evolutionary advantage in most of the world's habitats. The complex optical processing system that has evolved in higher vertebrate animals gathers, focuses, detects, transduces, and interprets incoming visible light. The cornea resides at the front end of this imaging system, where it provides a clear optical aperture, substantial refractive power, and the structural stability required to protect the fragile intraocular components. Nature has resolved these simultaneous design requirements through an exceedingly clever manipulation of common extracellular-matrix structural materials (e.g., collagen and proteoglycans). In this review, we (a) examine the biophysical and optical roles of the cornea, (b) discuss increasingly popular approaches to altering its natural refractive properties with an emphasis on biomechanics, and (c) investigate the fast-rising science of corneal replacement via synthetic biomaterials. We close by considering relevant open problems that would benefit from the increased attention of bioengineers.Annual review of biomedical engineering 07/2010; 13:269-95. DOI:10.1146/annurev-bioeng-070909-105243 · 12.45 Impact Factor