Thank you for your question. Just treating one area can cause there to be some irregular skin color in the area. See a qualified office, Board Certified Plastic Surgeon, Board Certified Dermatologist to make a plan and determine your risk profile. I hope this helps!
Spot Treatment with Fractional 1540
Yes, it can be done as a spot treatment on dilated pores, acne scars and any other type of scars (surgical or non surgical).
1540 fractional erbium laser treatments should not change skin color
Because the 1540 is an erbium laser skin color change should not happen. Spot treatment of dilated pores, acne scars and other types of scars can certainly be done.
Spot treatment with Lux1540
In general, it is best to treat an entire face for best results. However, if you are using the Lux1540 to treat pores, for example, you may consider doing an isolated treatment of the T zone. I would not expect a difference in coloration as a result of treatment.