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S. Thota, J. Perrigin, W. Miller, N. Leach, J. Bergmanson, A. Back; Conjunctival Flaps in Silicone Hydrogel Lens Wearers . Invest. Ophthalmol. Vis. Sci. 2006;47(13):82.
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Silicone hydrogel contact lens wearers on a continuous wear schedule have recently reported on occasion to develop conjunctival flaps (CF), which are of unknown morphology. The purpose of this study is to describe the composition and cellular health of these features.
Two adapted silicone hydrogel lens wearers exhibited bilateral CF after approximately 1 week of continuous wear. One subject (S1) wore lotrafilicon B lenses with an 8.6 mm base curve and the other subject (S2) wore lotrafilicon A lenses with an 8.4 mm base curve. One flap from each eye of the two subjects was sampled using impression cytology with cellulose acetate filters. The specimens were subsequently stained with hematoxylin and microscopically analyzed. The cytoplasm to nucleus ratio was assessed in 20 peripheral cells and 20 internal cells in each CF. Each subject completed a validated dry eye questionnaire (DEQ).
The location of the CF was found inferiorly in S1 and superiorly in S2 approximately 1 mm away from the limbus and peripheral to the lens edge. CF cytology showed multi–layered tightly packed sheets of polygonal epithelial cells. All flaps had a uniform cytological composition. In both subjects, all peripheral cells displayed a nucleus–cytoplasm ratio of 1:2. 65% of the internal cells in S1 were found to be 1:1 while 35% had a 2:1 ratio. For S2, 25% of the internal cells were found to be 1:1 and 75% were 2:1. Similar nuclear cell size and shape was noted in all cells within the CF, which also contained goblet cells. No inflammatory cells, basement membranes or stromal tissue were observed in any of the samples examined. S1 and S2 reported mild dry eye symptoms and scored normal and abnormal on the DEQ, respectively.
CEF appear strictly comprised of healthy and vital epithelial cells as well as goblet cells. The likely etiology may be mechanical in nature due to the shape of the lens edge together combined with the higher modulus of the silicone hydrogel material. We propose that the edge of the lens is impinging and prematurely separating superficial from deeper conjunctival cells and, thus, forming a heap–like flap.
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