Toric Calculation

One component of a glasses prescription is the astigmatism. There is a lot more to astigmatism than how it manifests in a glasses prescription, but it is an informative simplification to think about it as part of the glasses prescription. The other major component of a glasses prescription is the degree of nearsightedness or farsightedness.

When we choose to alter astigmatism using a lens implant, we often use a lens that has its own astigmatism, called a toric lens implant. Of course, the idea is to use a lens implant that has the astigmatism that would be in the glasses, so then the glasses would have zero astigmatism.

There are different ways to calculate what astigmatism a lens implant should have. In the January 2023 edition of the Journal of Cataract and Refractive Surgery, Li Wang and Doug Koch published an article that showed that we are getting better at measuring more components of what adds up to the “final” astigmatism. Until recently, we did not have a useful way of measuring that many components of the astigmatism, so Drs. Wang and Koch are definitely demonstrating progress.