Extended Wear in Perspective

Uptake and Release of Dexamethasone Phosphate From Silicone Hydrogel and Group I, II, and IV Hydrogel Contact Lenses

“…On eye closure, the oxygen delivery to the ocular surface by a contact lens material is substantially reduced, 25,26 potentially resulting in severe hypoxic conditions, which may impede the healing rate of an already compromised ocular surface in the case of ocular surface inflammation or infection. Traditional hydrogel materials based on poly-2-hydroxyethyl methacrylate (HEMA) do not provide sufficient degrees of corneal oxygenation during overnight wear to prevent corneal hypoxia, 27 and there is also an increased risk of microbial keratitis with these materials.…”

The Repeatability of Corneal Thickness Measures

“…Valid and repeatable estimates of corneal thickness are necessary to determine the level of corneal edema and, thus, to ensure that a contact lens is appropriate for extended wear. 1 Corneal thickness measures are also critical in determining patient eligibility for refractive surgery, the safety of a given procedure, and the amount of correction that can be performed while maintaining cornea stability postoperatively. 2,3 A number of techniques may be used to measure corneal thickness.…”

Adverse Events and Discontinuations During 18 Months of Silicone Hydrogel Contact Lens Wear

“…8,12 In this study, approximately half the subjects wore lenses on a daily-wear basis, and results have shown a higher incidence of adverse events with continuous wear than with daily wear of silicone hydrogel lenses. 34 No significant differences were found in the incidence of discontinuations between lens types or wearing regimens. The latter is surprising because of the difference of adverse events between lens types and wearing regimens and may be attributed to the population recruited in this study.…”

“…10,29 Differences in materials, designs, and modulus of rigidity between the two lenses do not seem to play an important role in the development of mechanically related adverse reactions owing to the similar incidence of CLPC and SEALs between the two lens types found in this study. 18,32 A higher incidence of adverse events was found with continuous wear than with daily wear of silicone hydrogel contact lenses, 10,23,33,34 and this difference may be attributed to differences in epithelial cell size and desquamation, central epithelial thickness, and tear lactate dehydrogenase between the two modalities of wear. 35 It may also be attributed to differences in tear exchange and stagnation between the two wearing modalities.…”