  In a recent publication [Phys. Rev. Lett. 107, 103901 (2011)], Wahlstrand et
al. reported to observe no indications for the appearance of the higher-order
Kerr effect in a parameter regime that was previously found to display this
phenomenon [Opt. Express 17, 13429 (2009)]. Here we show that careful analysis
of the original experimental data of Wahlstrand et al. reveals a 22%
saturation, i.e., direct proof for the appearance of the higher-order Kerr
effect. In the light of these findings, the validity of Wahlstrand et al.'s
main conclusions appears highly questionable.
