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S Padroni, G Milne, DJ Schanzlin, CJ Connon, AJ Quantock; Ultrastructural Evaluation of the Corneal Stroma after a Lamellar Incision . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1697.
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Purpose: Established refractive surgeries such as LASIK routinely make use of lamellar incisions in the anterior cornea, several millimetres in diameter. We investigated some morphological characteristics of the corneal stroma healing after a microkeratome-made lamellar incision. Methods: Three adult rabbits underwent a surgical procedure whereby an anterior lamellar cap, 6mm in diameter and 80% deep, was resected from the cornea with a Barraquer microkeratome then re-sutured in place with a 10-0 nylon running suture. Gentamicin sulfate (12mg) and dexamethasone (1.2mg) were administered subconjunctivally, and the lid was sutured closed for 3 days to aid healing. One, two and three weeks after surgery corneas were prepared for transmission electron microscopy with Cuprolinic blue (0.05%) included in the fixative in a critical-electrolyte-concentration mode (0.1M MgCl2) to allow visualisation of negatively charged, sulfated proteoglycans. Results: In the weeks after surgery, corneas displayed regions of normal stroma along with some areas of stromal disorganisation. Tissue regions highly populated by sulphated proteoglycan filaments were readily identified, and invariably these filaments were much larger (often up to 300 nm long) than those in quiescent stroma. Comparison with other work (Rawe et al., Histochem. J. 1992;24:311-318) suggests that the large proteoglycans probably contain a sizeable chondroitin/dermatan sulphate component. On occasion, such proteoglycans were noted in close association with (possibly in the process of being produced by) stromal keratocytes. Conclusion: The removal and replacement of an anterior lamellar cap formed by a microkeratome results in the appearance of large, sulphated proteoglycan filaments in the cornea in the weeks after surgery. These types of molecule have been documented in other types of wound in the rabbit cornea (e.g. full-thickness penetrating, superficial mechanical keratectomy, laser photoablation), thus their appearance would seem to be a normal feature of wound healing.
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