During dermabrasion the upper layers of the skin are removed mechanically using a small wheel rotating at high speed. This can result in the smoothing out of irregularities in the skin's surface, thus improving its appearance. Dermabrasion can also achieve improvements in the structure of the skin's surface, in particular in the case of pronounced scars or irregular scar tissue; acne scars and, in some cases, also wrinkles. Alternatively ablative lasers (erbium lasers, CO2 lasers) can be used for this purpose; however dermabrasion allows more precise work and smoother transitions. A special scraping instrument is used to remove only the uppermost layer of skin. The layers underneath remain untouched. Treatment can be carried out without an anaesthetic or, if necessary, using a topical anaesthetic. Following treatment the skin will be reddened for a few days and may be somewhat swollen. Any exposure to the sun must be avoided for around 6 weeks afterwards.