Practitioner guidelines for continuous wear with high Dk silicone hydrogel contact lenses.
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Biomedical subjects
Publications and source records attributed to Deborah F Sweeney.
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PURPOSE: This study evaluated an improved perfluoropolyether polymer formulation designed for use as a corneal onlay to correct refractive error. METHODS: Collagen I coated perfluoropolyether lenticules were implanted in feline corneas exposing a 6-mm diameter area of lenticule surface for epithelial growth. A parallel series of sham-wounded corneas were also studied. All corneas were monitored clinically for 4 or 8 weeks after surgery when animals were terminated and corneas used for histology with light and electron microscopy. RESULTS: Postoperative epithelial growth began on days 1 and 2. Lenticule surfaces were fully epithelialized by days 5 to 11. Corneas remained clear, and the lenticules maintained epithelial cover until the designated time points. Histology of the implanted corneas showed that the lenticules were well tolerated by the cornea. Each lenticule was fully covered by a multilayered epithelium with microvilli, desmosomes, and a differentiated basal cell layer. Epithelial adhesive structures (basal lamina, hemidesmosomes, and anchoring fibrils) had assembled at the tissue-lenticule interface. CONCLUSIONS: Collagen coated perfluoropolyether lenticules implanted in the feline cornea supported the growth of a stable stratified squamous epithelium. These encouraging results are a step further in the development of a corneal onlay for correction of refractive error.
PURPOSE: The aim of this investigation was to measure levels of corneal staining in successful daily and extended wearers of disposable hydrogel contact lenses. METHODS: Twenty-four subjects on a daily wear (DW) schedule and 20 subjects on an extended wear (EW) schedule were examined at six-monthly intervals over a two-year period. Subjects wore two types of disposable hydrogel lenses. Measurements were taken from the eye wearing an etafilcon A contact lens only. The cornea was divided into five equally sized zones and the extent and depth of corneal staining were assessed on a zero to four scale. RESULTS: The overall levels of corneal staining were low with median values below or equal to grade 0.5 in all groups. There was no difference in the extent, depth or geographical distribution of corneal staining between the DW and EW groups. Staining was more frequently recorded in the superior and inferior areas of the cornea than in the central, nasal or temporal regions (Pearson's Chi-Square, p < 0.10). CONCLUSIONS: The mode of wear with disposable contact lenses is not a contributing factor to the amount of corneal staining seen in successful wearers. Low levels of corneal staining should be expected in successful DW and EW wearers.