muramidase and Refractive-Errors

The purpose of this study was to investigate the impact of using a rewetting drop (RWD) containing surface active agents (OPTI-FREE RepleniSH; Alcon, Fort Worth, TX) on the clinical performance and protein deposition when using a continuous-wear (CW) silicone hydrogel (SH) contact lens.. Subjects wore lotrafilcon A SH lenses on a 30-day CW basis for two consecutive 1-month periods while inserting either 0.9% unpreserved unit-dose saline (control) or multidose OPTI-FREE RepleniSH (test RWD). Subjective comfort and symptoms were assessed after 2 and 4 weeks with each product. After 1 month of wear with each product, lenses were collected and analyzed in the laboratory for total protein, total lysozyme, and percentage of denatured lysozyme.. Symptoms of dryness and comfort varied across the day regardless of drop type (p < 0.001) with dryness being maximal on waking, least in the middle of the day, and increased towards the evening. The test RWD provided greater comfort on insertion (p = 0.02), better visual quality (p < 0.01), and less mucous discharge on waking (p = 0.02) than the control product. Lysozyme deposition was significantly reduced after the use of the test RWD as compared to saline (0.73 +/- 0.5 microg/lens vs. 1.14 +/- 0.7 microg/lens; p < 0.001) as was total protein deposition (1.17 +/- 0.7 microg/lens vs. 1.86 +/- 0.8 microg/lens; p < 0.001). Lysozyme denaturation was also reduced with the use of the test RWD compared with the control (76 +/- 10% vs. 85 +/- 7%; p < 0.01).. The use of a RWD containing surface active agents provided greater subjective satisfaction, reduced lysozyme and total protein deposition, and reduced denatured lysozyme than a RWD containing saline alone.

Topics: Adult; Blotting, Western; Contact Lenses, Extended-Wear; Cross-Over Studies; Dry Eye Syndromes; Electrophoresis, Polyacrylamide Gel; Follow-Up Studies; Humans; Hydrogels; Muramidase; Ophthalmic Solutions; Prospective Studies; Prosthesis Design; Refractive Errors; Silicones; Surface-Active Agents; Tears; Treatment Outcome

The major complications with extended wear lenses are due to hypoxia and lens deposits. Certain patients tend to deposit proteins and lipids on the lens surface with daily wear and at a greater frequency during prolonged wear. A build-up of these deposits can be associated with decreased vision, conjunctival irritation, and giant papillary conjunctivitis. Frequent lens cleaning and the frequent use of concomitant topical artificial tears will hopefully reduce the incidence of lens deposits and their complications. Superficial circumlimbal vascularization occurs in a large percentage of patients who have worn lenses for weeks at a time. Corneal edema, ocular irritation, and decreased vision are also the hallmarks of a decreased oxygen supply to the cornea. A thin-loose-fitting lens will increase the percentage of patients who are able to successfully use extended wear lenses by increasing the amount of oxygen available to the cornea. Cessation or reduction in duration of lens wear will decrease the frequency and severity of this complication. Conjunctival and corneal infections are real risks; lens loss, breakage, deformation, or discoloration also occur during extended wear.

Topics: Calcium; Conjunctivitis; Contact Lenses, Hydrophilic; Cornea; Eye Diseases; Humans; Hypoxia; Keratitis; Lipid Metabolism; Muramidase; Proteins; Refractive Errors; Time Factors