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P. Fagerholm, N. Lagali, M. Griffith; Biosynthetic Corneas - Evaluation in Humans. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1508.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate biosynthetic constructs as substitutes for donor corneas in deep lamellar corneal grafting
Collagen-based biosynthetic corneas designed to mimic the extracellular matrix of the corneal stroma have been developed and extensively evaluated in a range of animal models over the last 7 years. Recombinant human collagen type III (RHC III) was crosslinked with watersoluble carbodiimides and fabricated into optically, corneal substitutes for transplantation. Following study approval of the Medical Product Agency, Sweden and the Human Ethics Committee, University of Linköping, Sweden ,a Phase I study was initiated. 10 patients who were scheduled for corneal grafting were enrolled into the study. Nine had keratoconus and one had a deep scar following Pseudomonas keratitis.A central 6 mm in diameter deep lamellar button was excised and was replaced by a 6.25 mm in diameter 500 µm thick construct. Six overlying sutures were used to anchor the graft. Topical 0.1% dexamethasone and chloramphenicol was used for the first 1 month postoperatively. The sutures were removed after 5-7 weeks.The patients were followed clinically evaluated for UCVA, BSCVA and VA with contact lenses. Sensitivity (Bonnet-Cochet) and tear production (Schirmer ) were tested. Photography, OCT (Visante), topography (Orbscan II) and in vivo confocal microscopy (Heidelberg) was documented.
At 9 months, all patients had stably epithelialized and implants were anchored by keratocyte ingrowth. The BCVA was ≥ 20/ 40 in 6 patients and ≥ 20/200 in all patients.The mean central thickness was 416.7 µm (SD± 75.4 µm). The mean Schirmer values were 16.3 mm / 5 minutes (SD: ± 8.4) in the operated eyes and 17 mm/ 5 minutes(SD: ±9.3) in the fellow eye. The mean sensitivity was lower in the operated eye than in the control fellow eye. In-vivo confocal microscopy revealed beginning ingrowth of corneal nerves .
Although the results at 1 year are yet to come, we nevertheless have shown for the first time that bioengineered collagen-based corneal substitutes are fully biocompatible and promote regeneration of corneal cells. They can be used as temporary patches , and in vitro studies show support of corneal limbal and endothelial cells . With further development and testing, such substitutes could be a complementary source of material for corneal transplantation.
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