For a patient with >2.50D corneal cylinder and a spectacle cylinder not equal to 1.5x corneal cylinder, which GP lens type is recommended?

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

Answer: (D)

When corneal astigmatism is high and the spectacle cylinder doesn’t match the corneal cylinder in magnitude or axis, a lens that can bring toricity to both surfaces is the best choice. A bitoric GP lens has toricity on the posterior surface to address the corneal astigmatism and toricity on the anterior surface to correct residual refractive/orientation-related astigmatism independently. This dual-surface control provides more reliable neutralization of total astigmatism and a stable, comfortable fit for cases where a single toric surface design isn’t sufficient.

Spherical lenses won’t correct the high astigmatism. A back-surface toric can help but may fall short if the spectacle-cyclinder relationship isn’t the typical one (e.g., not around 1.5x corneal cylinder) or if alignment issues arise. Front-surface toric alone can be unstable due to rotation and may introduce optical complications. Therefore, a bitoric design is the best option in this scenario.