If residual cylinder is 0.75 D OR greater AND at least 25% of the spherical refractive error, which lens type is recommended?

• A. A sphere
• B. A bifocal lens
• C. A spherical lens with higher index
• D. A toric lens

Answer: (D)

When there is meaningful astigmatism that the lens must correct, you choose a toric design. A residual cylinder of 0.75 diopters or more means the eye still has a noticeable cylindrical error after factoring the sphere, and if the spherical error makes up at least 25% of the total refractive error, that cylinder is clinically significant. A spherical gas-permeable lens won’t correct that cylinder, so vision will remain blurred along the astigmatic meridians. A toric gas-permeable lens, on the other hand, is made to correct cylinder and axis, providing a sharper, more stable vision by neutralizing the astigmatic component while also delivering the spherical correction. The other options don’t address asteroid correction: a spherical lens can’t fix cylinder, a bifocal lens targets near vision, and a spherical lens with higher index only reduces thickness without correcting astigmatism.