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Ping Situ, David J. McCanna, Maud Gorbet, Lyndon W. Jones; Confocal Imaging Of Hyper-reflective Corneal Epithelial Cells During And After Contact Lens Wear. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4698.
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Hyper-reflective corneal cells have been observed with solution-induced corneal staining (SICS). In an attempt to understand the cellular basis of the hyper-reflective corneal cells in SICS, this study examined corneal epithelial cells during and after contact lens wear using in vivo confocal and laboratory-based confocal microscopy.
The study used a double-masked, randomized and contralateral eye design; six participants wore a balafilcon A lens soaked overnight in polyhexamethylene biguanide (PHMB)-based solution in the test eye, while a balafilcon A lens pre-soaked in hydrogen peroxide-based solution served as a control in the contralateral eye. In vivo confocal microscopy was used to examine the corneal epithelium before and after lens removal and hyper-reflective cells of given frames were counted manually. Corneal cells were collected by saline irrigation using the Ocular Surface Cell Collection Apparatus (OSCCA). The viability of shed epithelial cells was assessed by laboratory-based confocal microscopy using fluorescent viability dyes. In one group, sodium fluorescein was instilled prior to cell collection. Corneal fluorescein staining was also graded after lens removal and eye irrigation.
The number of hyper-reflective cells in the epithelium observed using in vivo confocal microscopy and the corneal staining score by conventional slit lamp were significantly higher with the combination of balafilcon A and PHMB-based solution compared to the control (all p< 0.02). Hyper-reflective cells in the epithelium were observed prior to lens removal and remained visible after lens removal and the OSCCA wash with buffered saline. Irrespective of lens-solution combination, cells that were collected from the corneas following irrigation revealed both a population of viable fluorescein-stained cells and a population of fluorescein-stained cells in the process of undergoing apoptosis.
Clinical and laboratory confocal microscopy is capable of studying human corneal epithelial cells during and after contact lens wear. A direct link between hyper-reflective cells, shed epithelial cells and fluorescein-stained cells could not be established in this study.
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