PRECISION BALANCE 8|4® is a patented lens design for toric contact lenses. It was developed by Alcon, the global leader in innovative eye care.
PRECISION BALANCE 8|4 is a modified prism-ballast design. Unlike traditional prism-ballasted designs, this design features two anchor points at 8 and 4 o’clock, rather than just one. With PRECISION BALANCE 8|4, the upper lid provides pressure on the top of the lens, pushing it towards the lower lid. The lower lid then keeps the anchor points balanced for stabilization.
Aside from ensuring exceptional stability, PRECISION BALANCE 8|4 also maximizes oxygen transmissibility at 6 o’clock. In all, these modifications allow for a wider optic zone that helps to provide reliable, consistent vision during blinking and eye movements.
Why is stability key for toric contact lenses?
Astigmatism is an imperfection in the curvature of the eye that causes blurred vision. In astigmatism, the refraction of the eye differs between the vertical and horizontal planes.
People with astigmatism experience blurred vision when wearing standard contact lenses. This is where toric lenses come in. These contacts provide different refractive powers on the vertical and horizontal planes to correct astigmatism. The planes must be oriented in just the right way and remain stable to correct vision.
To help orient the lenses properly and keep them in place, manufacturers design toric contacts with certain stabilizing features. These features include:
- Thin-thick zones – Some toric contacts have areas that are thicker than the rest of the lens. These thick zones help to orient the contacts properly and keep them from rotating.
- Lens truncation – When a lens is truncated, a portion of it is cut off. The size of the portion cut off will depend on the size of the lens. The truncation primarily serves to stabilize the lens when the lower flat edge comes to lie adjacent to the lower eyelid margin.
- Ballasting – In ballasting, a prism is used to orient and stabilize the lens. In contact lenses with a prism-ballast design, a portion of the lens is heavier than the rest. This portion acts as a weight to keep the lens from rotating out of its proper position. Manufacturers determine the amount and location of the prism in their toric contact lens designs, so no two designs are the same.
Contact Lenses With PRECISION BALANCE 8|4 Lens Design
PRECISION BALANCE 8|4 is unique to Alcon’s Air Optix® for Astigmatism, Air Optix plus HydraGlyde® for Astigmatism, Dailies Total1® for Astigmatism, and PRECISION1® for Astigmatism.
AIR OPTIX for Astigmatism contact lenses provide superior comfort from day 1 to 30 for those with astigmatism. PRECISION BALANCE 8|4 design keeps these contacts in place to avoid blurriness, while SmartShield® Technology protects them from irritating surface deposits.
AIR OPTIX for Astigmatism contacts are monthly disposable lenses that can be worn daily for up to 30 days or continuously for up to six nights and seven days.
AIR OPTIX plus HydraGlyde for Astigmatism contact lenses feature a combination of innovative technologies from Alcon to keep your eyes healthy and your vision clear. PRECISION BALANCE 8|4 design keeps the contacts in place to avoid blurred vision, while SmartShield Technology and HydraGlyde Moisture Matrix ensure a comfortable contact lens-wearing experience.
As monthly disposable contact lenses, AIR OPTIX plus HydraGlyde for Astigmatism can be worn daily for up to 30 days. They’re also FDA-approved for up to six nights and seven days of extended wear.
3. DAILIES TOTAL1 for Astigmatism
DAILIES TOTAL1 for Astigmatism are the first and only daily disposable toric contact lens to feature Water Gradient surface material. This lens material features a gradual increase in water content at the surface, so all that touches the eye is a cushion of moisture.
DAILIES TOTAL1 for Astigmatism also feature PRECISION BALANCE 8|4 design for exceptional stability and SmarTears® Technology for comfort that lasts.
PRECISION1 for Astigmatism are daily disposable toric contact lenses designed to provide excellent visual acuity to astigmatic patients. Featuring the proven PRECISION BALANCE 8|4 design, these contacts ensure a stable contact lens-wearing experience. PRECISION1 for Astigmatism also feature SMARTSURFACE® Technology for superior lens-surface moisture stability.
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