For astigmatism contact lens conversion formulas refer mainly to the principle of equivalent spherical lenses for conversion. Astigmatism is obtained by dividing the prescription by 2 and adding it to the spherical lens to get the equivalent spherical lens prescription. If you try on frames according to the equivalent spherical lens, you can wear contact lenses according to this prescription if you don’t get dizzy when looking at things and if they are more permanent and clear. However, if you do not see clearly or are dizzy, you cannot simply wear glasses at this prescription. If you are more dizzy and need to reduce the prescription, but after reducing the prescription it may also cause unclear looking, you should consider toric contact lenses, because nowadays some contact lenses are designed to replace or appear as toric prescription, so wearing contact lenses with toric design can solve this kind of unsuccessful conversion problem.