Inordertodeterminetheappropriatetreatmentinterval,267patientswhounderwent3sessionsoftreatmentwithQ-switchedalexandritelaserwerepidedinto4groupsaccordingtotreatmentinterval,andtheirclinicalresponseswerecompared.Amongthem,187wereaskedabouttheprocessofpigmentfading.Moreover,lightandtransmissionelectronmicroscopywereperformed.Itwasnotedthattheclinicalresponseofthe5-6monthintervalgroupwassignificantlybetterthanthatofthe3-4monthgroup,butshowednosignificantdifferencefromthatofthe7-8or≥9monthgroup.80.21%ofinvestigatedpatientsstatedthatmarkedpigmentfadingcouldnolongerbeobserved7monthsafterirradiation.4monthsafterirradiation,thedegeneratedmelanosomesandcelldebriswerestillscatteredamongcollagenfibers,scavengedgraduallybymacrophage.Inconclusion,anappropriatetreatmentintervalis5-6months.
