Toric contact lens featuring BLINK STABILIZED™ design has no vertical prism
SEATTLE, WA (October 25, 2013) – A new study from Johnson & Johnson Vision Care, Inc. measured seven leading toric soft contact lenses for the amount of vertical prism in the central optic zone, which can disturb a patient’s binocular vision function. All designs except for ACUVUE® OASYS® Brand Contact Lenses for ASTIGMATISM had vertical prism in the optic zone, the study found. The findings were presented today at The American Academy of Optometry meeting.
“This study demonstrates that the type of toric lens design can have an effect that goes beyond stability,” says study co-author Giovanna E. Olivares, O.D., FAAO, Global Platform Director, VISTAKON® Division of Johnson & Johnson Vision Care, Inc. “We know that vertical prism of 0.5 PD or more may lead to symptoms related to binocular disturbances, especially in patients with fragile binocularity.1,2 Therefore, in monocular astigmats fit with a toric soft contact lens or patients wearing a mix of toric lens designs, induced vertical prism imbalance could create or exacerbate disturbances in binocular vision function. Wearers fit with ACUVUE® OASYS® Brand for ASTIGMATISM, which utilizes BLINK STABILIZED™ design, would not be prone to these visual disturbances due to an induced vertical phoria.
“Clinical studies have not been done to fully characterize the clinical effects of differences in base down prism among different contact lenses,” she added.
About the Study
Seven toric soft contact lenses featuring various stabilization methods were measured for the amount of vertical prism in the central 6.0 mm of the optic zone. The vertical prism of ACUVUE® OASYS® for ASTIGMATISM, Air Optix® for Astigmatism, Avaira® Toric, Biofinity® Toric, Clariti™ Toric (monthly), Purevision2® for Astigmatism, and Purevision® Toric was computed using published refractive index and average thickness change vertically in the central 6.0 mm of the optic zone on a full lens thickness map. Thickness maps were measured using a scanning transmission microscopy method. Eight parameter combinations per product covering -6.00 DS to +3.00 DS and -1.25 DC at axes 90° and 180° were evaluated.
The results show that all designs except for ACUVUE® OASYS® for ASTIGMATISM had vertical prism in the optic zone. Mean prism ranged from 0.52 PD to 1.15 PD. The variability in prism was up to 20 percent of the mean. One design had mean prism of about 0.50 PD, three had about 0.75 PD, three had between 0.75 and 1.0 PD, and one had over 1.0 PD. Three designs had prism that varied with sphere power. The amount of prism measured in ACUVUE® OASYS® for ASTIGMATISM was statistically lower than all other toric contact lenses tested (ANOVA p<0.001)
The study was supported by funding from Johnson & Johnson Vision Care, Inc.
Source: Hawke, R, Osborn-Lorenz, K, Olivares, G, Sulley, A, “Vertical Prism in Toric Soft Contact Lenses.” Poster presented October 25, 2013 at The American Academy of Optometry 2013 meeting.
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.
ACUVUE®, ACUVUE® OASYS®, BLINK STABILIZEDTM Design, and VISTAKON® are trademarks of Johnson & Johnson Vision Care, Inc.
Third party trademarks used herein are trademarks of their respective owners.
References:
- Jackson DN and Bedell HE. Vertical Heterophoria and Susceptibility to Visually-Induced Motion Sickness. Strabismus 2012. 20(1) 17-23.
- du Toit R, Ramke J, Brian G. Tolerance to prism induced by ready-made spectacles: setting and using a standard. Optom Vis Sci. 2007 Nov;84(11):1053-9.