Multiple studies have been performed to examine the efficacy of microdermabrasion. Initial studies using microdermabrasion assessed their effects in patients suffering from acne scars, traumatic scars, surgical scars and burns scars. Patients reported significant improvements in appearance. Subsequent studies identified measured improvements in skin roughness, pigmentation and overall appearance in patients seeking facial rejuvenation. Effects of microdermabrasion on deeper wrinkles extending beyond the epidermis and into the dermis were found to be limited. Microscopic studies demonstrated improvements in the thickness of the epidermis as well increased levels of collagen and elastin under the microscope. More recently researchers have focussed on the effects of microdermabrasion in combination with other procedures.