Microneedling using 1.5-2mm depth: how frequently?

Hello, thanks for sharing your query. Microneedling can be done every 3-4 wks to get optimal results. Microneedling alone may not be sufficient to treat all type of scars and may need additional treatment like peels, dermaabrasion, punch grafting, subsision, laser etc. Microneedling is not safe in under eye region as the skin is very thin and can cause bruising. Consult a board certified dermatologist.

Dear rocknroutlaw,
To achieve the best outcome with microneedling, I would recommend seeing an experienced physician. Different areas of the face require different depths and the lower eyelids can be treated as well but the skin is typically thin in the area so you should be careful. Microneedling may improve some of your acne scars but may not get rid of the deep ones which may require other treatments such as TCA cross. The frequency of the microneedling depends on the depth but typically can be repeated at monthly intervals. 
Best,
Dr. Liu