Precision Balance 8|4™ is a trademarked, unique design for toric contact lenses that was developed and implemented by Alcon Inc.
The goal of this design is a stabilized lens fitting and wearing experience using two specific points of stability and to reduce any type of interaction of the lens with the eyelid. Alcon also implemented three scribe marks at 3, 6 and 9 o'clock to support the correct insertion and fitting of the lenses.
Precision Balance 8|4 further explained
Stability is key, especially when wearing contact lenses for astigmatism. When blinking, the eyelids engage the lens at 8 and 4 o'clock. These two areas are slightly thicker than the rest of the lens, and due to their interaction with the eyelids, they support stabilizing the lens and locking in acuity with just five degrees or less of oscillation with each blink. Oscillation is a measure of how much your lens rotates clock- or counter-clockwise during that short moment of blinking. Keeping the level of oscillation as small as possible encourages a more stabilized lens and a better overall lens wearing experience.
Are there any scientific studies on Precision Balance 8|4?
Yes. There are some interesting studies regarding the effectiveness of Presision Balance 8|4 with its approach to minimize contact lens rotation and disalignement caused by eye movement.
One study 1 looks at the impact of various factors on visual performance, such as clock-wise orientation and position, readjustment time, and contact lens center deviation. The study includes four popular toric lenses and one Alcon lens with Precision Balance 8|4 design. The findings suggest that Alcon's lens with Precision Balance 8|4 design helps to mitigate the effects of blinking and eye movement by reducing lens rotation and vertical misalignment.
Another study from 2008 2 compares one toric Alcon lens to one Acuvue lens and compares - among others - visual acuity, vertical and horizontal lens orientation, comfort, and overall preference. The results indicate a general prefererence for Alcon's lens with Precision Balance 8|4 due to better handling and fewer fluctuations in vision stability.
Lenses with Precision Balance 8|4™ Design
AIR OPTIX plus HydraGlyde for Astigmatism is a silicone hydrogel lens introduced by Alcon...
1 Objective evaluation of static and dynamic behavior of different toric silicone-hydrogel contact lenses
by: Ángel Sánchez-García, Javier González-Pérez - Faculty of Optics and Optometry, University of Santiago de Compostela
Published by: Science Direct - April 2021
2 Comparing Two Silicone Hydrogel Toric Lenses
by: Jeffrey Sonsino, OD, FAAO
Published by: Contact Lens Spectrum