For a patient with >2.50D corneal cylinder and a spectacle cylinder equal to 1.5x the corneal cylinder, which GP lens type is recommended?

• A. Spherical
• B. Back surface toric
• C. Front surface toric
• D. Bitoric

Answer: (B)

When corneal astigmatism is high, using a toric GP lens helps neutralize the cylindrical error directly at the cornea. In this scenario, the corneal cylinder is greater than 2.50 D and the spectacle cylinder ends up about 1.5 times the corneal cylinder, so the primary goal is to neutralize the corneal curvature with a stable, predictable lens design. A back surface toric GP places the toricity on the posterior lens surface to match the corneal contour, which effectively neutralizes the main astigmatic error while keeping the anterior surface relatively simple. This setup provides better rotational stability and centration than a front surface toric, which is more prone to rotation and less predictable in high astigmatism. Bitoric lenses, while useful for complex cases, add complexity and aren’t typically needed here if the main corneal cylinder can be addressed with the back surface toric alone. Therefore, back surface toric is the most appropriate choice.