Convert your eye prescription to visual acuity (a 20/20 vision system).
Your eye prescription is measured in Diopters. This measures the focusing power of your glasses. Conversely, 20/20 vision systems measure your visual acuity. This is a measure of how well you can see things.
We use the following paper as a source for the conversion engine; Frank Thorn et al., Optometry and Vision Science, Vol. 67, No. 1, pp.3-7.