Will TCA Peel Minimize Demarcation Lines from Phenol Peel?

Deep laser or phenol depigments, reduces pigment permanently. Patchy application of deep peeling agents will result in a patchy appearance, either through removal of sun damage or through direct depigmentation (including apoptosis).

The best way to camouflage a problem with demarcation is to resurface all around the area, usually with the Co2 laser set to a very conservative setting.

There is unfortunately no accepted way to bring the pigment cells back to life.

We have long given up phenol peels for this reason, and only perform CO2 laser conservatively.

We never do deeper peels just around the mouth or the eyes either to avoid a patchy "raccoon" look..

If you are extrmemely fair (ie burn) nd do not tan, you could consider phenol under the eyes with TCA for blending. It sounds like your doctor feels you need a lighter peel on the rest of your face and a deeper peel under your eyes.
Another approach that may look more natural is to do a fractionated CO2 laser, which would tighten under your eyes and can be blended on the rest of the face.
The problem with phenol is that it does lighten the skin because of it's effect on melanocytes. This lightening doesn't really become apparent for several months afterward and is difficult, if impossible, to re-pigment.
I hope this helps.
Dr. Sikorski

Phenol is best reserved for patients with extremely fair skin. They usually do not get the line of demarcation because it blends well enough with the fair skin. It is hard to predict if TCA will blend well enough if you are medium complexioned. If you are looking for nice results with line effacement and tightening of lax skin, consider fractional CO2. It will improve lines as well as tighten the skin around and above the eyes and if done over the entire face, it will blend better.