The last two answers are correct and hence are the same. Your equation is $$\mathrm{log}_{10}\frac{d}{L} = a$$ $$\frac{d}{L} = 10^{a}$$ $$L = \frac{d}{10^{a}} = \frac{d}{10^{-0.22}} = d\,10^{0.22}$$ We let $a=-0.22$, $d=$ corneal diameter, and $L=$ axial length.