AIM: To investigate the safety and efficacy of intense pulsed light in the treatment of severe chronic ocular graft-versus-host disease.METHODS: Prospective randomized controlled study. A total of 35 cases(35 eyes), who had a history of allogenic hematopoietic stem cell transplantation(allo-HSCT), admitted to the Affiliated Hospital of Xuzhou Medical University from January to September 2022 and were diagnosed by our hospital's hematology and ophthalmology departments with severe chronic ocular graft-versus-host disease(coGVHD)were selected. One eye was randomly selected for inclusion in the study if both eyes met the enrollment criteria, and the eye was selected if a single eye met the enrollment criteria. All patients were administrated with Dextran and Hypromellose eye drops 4 times a day and Cyclosporine eye drops twice a day. The experimental group was additionally treated with intense pulsed light, once every two weeks a week, for 4 times in total. The evaluation indicators were evaluated before treatment and 2wk, 1 and 2mo after treatment. The evaluation indicators include ocular surface disease index(OSDI)score, best corrected visual acuity(BCVA), intraocular pressure(IOP), tear meniscus height(TMH), non-invasive break-up time(NIBUT), conjunctival injection score(CIS), meibomian gland area proportion(MGAP), meibomian gland evaluation(MGE), cornea fluorescein staining(CFS), conjunctival lissamine green staining(CLGS), lid margin abnormality score(LMAS), and Schirmer's Ⅰ test(SⅠt).RESULTS: After treatment, OSDI score, TMH, NIBUT, BCVA, CFS, CLGS, and CIS improved in both groups compared with those before treatment(all P<0.05), with NIBUT, CFS and CLGS showing more significant improvements in the test group. In the control group, MGAP, MGE of the upper and lower eyelids and LMAS did not change significantly before and after treatment(P>0.05), while in the experimental group, MGAP of the lower eyelids, MGE of upper and lower eyelids and LMAS improved compared with those before treatment(P<0.05), except for MGAP of the upper eyelids, which did not differ from that before treatment(P>0.05). There was no difference in SⅠt and IOP between the two groups before and after treatment(P>0.05). Patients did not experience adverse reactions such as skin burns, redness and swelling in the treated area and eyelash loss during the follow-up period.CONCLUSION: Intense pulsed light is safe and effective in the treatment of severe coGVHD, which can significantly improve the symptoms and signs of patients and enhance the stability of tear film.