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.
Lenses with Precision Balance 8|4™ Design