There are many kinds of lasers, different lasers, different diseases, different intervals during treatment, and the time required varies due to individual differences and other reasons. For example, intense pulsed light, or photorejuvenation, requires two sessions with an interval of 3-4 weeks. Laser hair removal requires different intervals depending on the hair area and growth rate. As the treatment cycle increases, the rate and density of hair growth decreases accordingly, and the treatment interval will gradually increase to about 3-8 weeks. For the treatment of nevus of Ota with Q-modulated laser, the interval period is about 3 months at the beginning, and then the interval period needs to be extended as the color of the spot becomes lighter and lighter. For example, Q-modulated laser treatment of cheekbone nevus requires a longer interval of about 3-6 months. Therefore, the interval of laser treatment is determined by different factors.