The idea that neurotoxins lift the brow is an urban myth. Neurotoxins paralyze muscle. Injecting the forehead with neurotoxins will not lift, Antagonistic muscles can be played against each other. paralyzing the crows feet and not the forehead can sometimes afford some lateral lift. However, in this case, asymmetry of the crows feet could be accentuated. Treating the left forehead would be easier to drop the high side, but you would have both sides low. Also when treating sides differently, you may look good at rest, but have objectionable asymmetries when you animate. Surgery may be an option. Your best bet is to seek a meticulous examination by a board certified plastic surgeon, and get two to three different opinions. Non surgeons usually recommend non surgical options only, which may not be in your best interest.