Toric Lenses Practice Test

The main idea here is how tolerant toric lenses are to axis misalignment. A toric lens corrects astigmatism along a specific axis, and if that axis rotates away from the ideal orientation, the cylinder correction is no longer perfectly aligned. For a medium-strength cylinder, the residual blur remains essentially unnoticeable up to about 10 degrees of axis misalignment, so visual acuity stays stable. Beyond roughly 10 degrees, the misalignment creates enough residual astigmatism to degrade VA. That’s why the range of about plus or minus 10 degrees is the correct window. A smaller range like plus or minus 5 degrees is within that tolerance but doesn’t reflect the full stability the lens can provide, while larger misalignments such as plus or minus 15 or 20 degrees exceed the tolerance and lead to poorer acuity.