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JJ McNally, RL Chalmers, CD McKenney; Factors Associated With Change in Refractive Error During a Year of 6 Night or 30 Night Extended Wear . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3110.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the factors associated with clinically significant changes in myopia during a year of 6 night or 30 night extended wear (EW). Methods: After informed consent, 1395 subjects were randomized to wear either etafilcon A lenses for 6 night EW or lotrafilcon A lenses for 30 night continuous wear (CW) for one year. Subjective refractions at baseline and 12 months were compared to identify risk factors associated with changes of 0.625 D or more. Results: Of the 1158 eyes that wore etafilcon A lenses for the full year, 98 eyes (8.5%) increased in myopia by 0.625 D or more (range -0.625D to -2.63 D). Of the 966 eyes that wore lotrafilcon A lenses for the full year, 14 eyes (1.5%) increased in myopia by 0.625 D or more (range -0.625D to -1.00 D) (p<0.0001, Chi-square). Of these, 2.1% of the eyes wearing etafilcon A lenses increased by 1.00D or more compared to 0.2% of the eyes wearing lotrafilcon A lenses. Interestingly, 4.9% of the lotrafilcon eyes decreased in myopia by 0.625D or more compared to 0.8% of the etafilcon eyes. Of these, the mean refractive error was -4.68 (+/- 1.53) for the lotrafilcon A eyes and -3.11 (+/- 3.56) for the etafilcon A eyes. Risk factors studied for these refractive error changes included baseline refractive error, prior contact lens wearing history, age and gender. Conclusion: Fewer subjects experienced myopic increases while wearing lotrafilcon A lenses compared to etafilcon A. A substantial number of lotrafilcon A subjects showed clinically significant reduction in myopia. These results support the hypothesis that hypoxia is an important factor influencing myopic increases during extended wear. Patients using EW should be monitored for refractive error changes at follow-up exams.
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