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K.L. Richdale; Evaluation of Presbyopic Soft Contact Lens Modalities . Invest. Ophthalmol. Vis. Sci. 2005;46(13):694.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare bifocal soft contact lenses with monovision for the correction of presbyopia Methods: We conducted a crossover study of 20 patients. Eligible subjects had different spectacle prescriptions for distance and near, with a reading add of at least +0.75 diopters (D). Spherical refractive error had to be between +6.00 and –10.00 D with less than –1.00 D of astigmatism. Subjects must not have worn either monovision or bifocal contact lens correction in the past. Patients were randomized into either bifocal (Bausch & Lomb Soflens Multifocal) or monovision (Soflens 59) for the first month. After one month of wear, they returned for a visual function assessment by a masked examiner. They were then re–fit into the other lens modality and the process was repeated. We measured visual acuity using a Bailey–Lovie chart (distance and near, high– and low–contrast), visual performance using a computer–based letter search, and stereo acuity. We also recorded the patient's final lens preference. Results:When asked which lens modality they preferred, 15 of the 20 patients chose the bifocal contact lens. The monovision system reduced stereo acuity compared to baseline (by 72±120 sec arc, p=0.02) and to the bifocals (by 53±101 sec arc, p=0.03). Both presbyopic contact lens modalities reduced distance, low–contrast visual acuity compared to baseline (by four letters for the bifocal, –0.08±0.11 logMAR, p=0.003; by three letters for monovision, –0.06±0.11 logMAR, p=0.04). The monovision system demonstrated more errors on a computer–based letter editing task (1.18±2.07 errors, p=0.03). Conclusions: The Bausch & Lomb Soflens Multifocal contact lenses appear to be superior to the monovision system. Stereo acuity, low–contrast visual acuity, and computer–based performance tasks are adversely affected by monovision contact lenses. Only distance, low–contrast visual acuity seems to be hindered by bifocal contact lenses. We would like to acknowledge Bausch & Lomb for their donation of the bifocal and monovision contact lenses and Renu Multipurpose solution.
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