Just apply the light effect to the text layer. If you have its background transparent, the light will not affect it. If the background is not transparent yet, use Photoshop to make it and go to After Effects.
Select the point you want, press Crtl+Shift+D it will slpit the layer in two, then go to the second one and trim it. But of course if you have a lot of frames to cut, Premiere is the best option.
Thanks for the help, I meant for “flatten text” something like a very thin text, no depht… sorry for my English, I’m brazilian and sometimes I write funny thing, because I don’t know the right way to say it… I’m still learning.
If your effect from Photoshop does not appear on After effects, you can on Photoshop create a new empty layer and merge it to the layer with the effect, by doing this, After will recognize all effects that Photoshop creates.