Low-Cost and Readily Available Tissue Carriers for the Boston Keratoprosthesis: A Review of Possibilities

Journal of Ophthalmology (Impact Factor: 1.43). 11/2013; 2013(6):686587. DOI: 10.1155/2013/686587
Source: PubMed


The Boston keratoprosthesis (B-KPro), currently the most commonly used artificial cornea worldwide, can provide rapid visual rehabilitation for eyes with severe corneal opacities not suitable for standard corneal transplantation. However, the B-KPro presently needs a corneal graft as a tissue carrier. Although corneal allograft tissue is readily available in the United States and other developed countries with established eye banks, the worldwide need vastly exceeds supply. Therefore, a simple, safe, and inexpensive alternative to corneal allografts is desirable for the developing world. We are currently exploring reasonable alternative options such as corneal autografts, xenografts, noncorneal autologous tissues, and laboratory-made tissue constructs, as well as modifications to corneal allografts, such as deep-freezing, glycerol-dehydration, gamma irradiation, and cross-linking. These alternative tissue carriers for the B-KPro are discussed with special regard to safety, practicality, and cost for the developing world.

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Available from: Roberto Pineda, Feb 12, 2014
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    ABSTRACT: Purpose: The aim of this study was to develop a modified ex vivo corneal cross-linking method that increases stromal resistance to enzymatic degradation for use as a carrier for the Boston keratoprosthesis. Methods: Ex vivo cross-linking of human corneas was performed using Barron artificial anterior chambers. The corneas were deepithelialized, pretreated with riboflavin solution (0.1% riboflavin/20% dextran), and irradiated with ultraviolet A (UV-A) light (λ = 370 nm, irradiance = 3 mW/cm) for various durations. The combined effect of UV-A and gamma (γ) irradiation was also assessed using the commercially available γ-irradiated corneal donors. The corneas were then trephined and incubated at 37°C with 0.3% collagenase A solution. The time to dissolution of each cornea was compared across treatments. Results: Deepithelialized corneas (no UV light, no riboflavin) dissolved in 5.8 ± 0.6 hours. Cross-linked corneas demonstrated increased resistance to dissolution, with a time to dissolution of 17.8 ± 2.6 hours (P < 0.0001). The corneal tissues' resistance to collagenase increased with longer UV-A exposure, reaching a plateau at 30 minutes. Cross-linking both the anterior and posterior corneas did not provide added resistance when compared with cross-linking the anterior corneas only (P > 0.05). γ-irradiated corneas dissolved as readily as deepithelialized controls regardless of whether they were further cross-linked (5.6 ± 1.2 hours) or not (6.1 ± 0.6 hours) (P = 0.43). Conclusions: Collagen cross-linking of the deepithelialized anterior corneal surface for 30 minutes conferred optimal resistance to in vitro keratolysis by collagenase A.
    Cornea 07/2014; 33(9). DOI:10.1097/ICO.0000000000000185 · 2.04 Impact Factor
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    ABSTRACT: Over 2 decades of research, several design modifications, and improvements in post-operative management have made Boston keratoprosthesis (B-KPro) a viable option for patients with corneal blindness for whom traditional keratoplasty procedure has a very low probability of success. In this systematic review, we examined the indications, visual outcomes, complications and retention rate of the literature published in the past 10 years (2005-2014). While most of the studies report smaller datasets (typically <50 eyes), some of the recent multicenter studies have reported large datasets (up to 300 eyes). Most of the literature is published from the US, however last few years have witnessed some papers reporting the successful use of B-Kpro from developing countries or arid climatic conditions (like the Kingdom of Saudi Arabia). Due to differences in the causes of corneal blindness in different geographic regions, newer indications for B-Kpro are emerging (e.g. trachoma). Additionally, improving clinical outcomes and increasing surgeon confidence have also expanded indications to include cases of unilateral visual impairment and paediatric age. We observed that there is growing body of evidence of successful clinical use of B-KPro; however, financial challenges, lack of trained surgeons, shortage of donor corneas must be overcome to improve accessibility of B-KPro.
    Saudi Journal of Ophthalmology 02/2015; 53(3). DOI:10.1016/j.sjopt.2015.02.001
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