Toric Soft Contact LensStability In Extreme Versions and Postural Positions Can Affect Orientation and Visual Acuity, Study Shows
Jacksonville, FL – Toric soft contact lens design affects lens stability and visual acuity, particularly during abnormal gaze movements, such as scanning a newspaper for information, gazing to the extreme side for changing lanes while driving, or playing sports, according to a new study. The research, which compared the effect of gaze direction and posture on toric lens orientation and visual acuity of contact lenses using either an Accelerated Stabilization Design or Prism Ballast Design, is published in the current issue of Contact Lens & Anterior Eye, the official journal of the British Contact Lens Association.
Fourteen subjects participated in the randomized, unmasked, non-dispensing study, Four lens types were assessed: ACUVUE® OASYS™ Brand Contact Lenses for ASTIGMATISM (VISTAKON®), Purevision® Toric (Bausch & Lomb), O2Optix® Toric (CIBA Vision) and Proclear® Toric (CooperVision).
In the first part of the study, subjects were positioned on their side and once lenses had settled, visual acuity was measured and photographs taken of the lens orientation position. In the second part, the subjects were positioned at a slit-lamp and video-recordings taken as they changed their gaze from the primary position to each of the eight cardinal directions of gaze.
In part one of the study, all lenses rotated as a result of change in posture and head position. With subjects in a recumbent position mean rotation ranged from 11.0° with ACUVUE® OASYS™ for ASTIGMATISM to 29.1° with Proclear® Toric. The consequent mean reduction in visual acuity ranged from 0.05 logMAR for ACUVUE® OASYS™ for ASTIGMATISM to 0.15 logMAR for Purevision® Toric and was significantly worse with Purevision® Toric and Proclear® Toric compared with ACUVUE® OASYS™ for ASTIGMATISM (P less than 0.05).
In part two of the study, lenses tended to show inferio-nasal rotation on upgaze and inferio-nasal rotation on downgaze. The ACUVUE® OASYS™ for ASTIGMATISM lenses showed significantly less rotation on inferio-nasal version than each of the other designs (P less than 0.005).
Fluctuating vision is one the main reasons for dissatisfaction among astigmatic patients, according to study author Graeme Young, MPhil, PhD, FCOptom, FAAO. “This research illustrates why patients may notice a greater degree of consistent vision when wearing ACUVUE® OASYS® for ASTIGMATISM,” he says.
The study was sponsored by VISTAKON®, a division of Johnson & Johnson Vision Care, Inc., marketer of ACUVUE® OASYS™.
Source: Young, G, McIlraith R, Hunt C. ’Toric Lens Orientation and Visual Acuity in Non-Standard Conditions.’ Contact Lens & Anterior Eye, February 2010, Pages 23-26.
ACUVUE® Brand Contact Lenses are indicated for vision correction. As with any contact lens, eye problems, including corneal ulcers, can develop. Some wearers may experience mild irritation, itching or discomfort. Lenses should not be prescribed if patients have any eye infection, or experience eye discomfort, excessive tearing, vision changes, redness or other eye problems. Consult the package insert for complete information. Complete information is also available from VISTAKON®, Division of Johnson & Johnson Vision Care, Inc., by calling 1-800-843-2020 or by visiting www.jnjvisioncare.com.
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ACUVUE®, ACUVUE® OASYS™, and VISTAKON® are trademarks of Johnson & Johnson Vision Care, Inc.
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