  In their article -Appl. Opt. 58, 1010_1015 (2019)- Gonz\'alez-Acu\~na et al
claimed:"an analytical closed-form formula for the design of freeform lenses
free of spherical aberration and astigmatism." However, as we show here, their
formula can only be applied when the object and image are both real and the
image is inversed, additionally, the refractive index in the object and image
media is the same. Here, we present the complete solution of this particular
formula.
