Back Toric GP lenses are more commonly used in patients with which type of astigmatism?

• A. WTR
• B. ATR
• C. Oblique
• D. No astigmatism

Answer: (B)

Back surface toric GP lenses correct corneal astigmatism by giving the lens a different curvature in two meridians on the backside. This setup works especially well when the cornea’s steep meridian is horizontal, a pattern known as against-the-rule astigmatism. The posterior toricity interacts with the tear film and eyelid dynamics to keep the lens more stable and well-centered, reducing rotation and providing clearer, more consistent optics. Because of this stability with ATR patterns, back toric designs are more commonly used for ATR astigmatism than for WTR or oblique patterns, or when there is no astigmatism.