BACKGROUND: To investigate the possible mechanisms by which cataract surgery aggravates meibomian gland dysfunction (MGD), we evaluated the changes in tear cytokines and ocular surface parameters after cataract surgery according to the preoperative MGD grade. DESIGN: Prospective, observational case series. PARTICIPANTS: A total of 50 eyes from 50 patients who underwent cataract surgery were included. METHODS: Patients were classified into two groups: Group I had no or minimal MGD, and group II had grades 2-4 MGD. Ocular surface parameters were measured, including tear film break-up time, Schirmer I test, ocular surface staining and Ocular Surface Disease Index, and tear cytokine levels were measured. MAIN OUTCOME MEASURES: The main outcomes were changes in ocular surface parameters and inflammatory tear cytokine concentrations. RESULTS: In group II, preoperative MGD grade, ocular surface staining, tear film break-up time and Ocular Surface Disease Index were worse, and mean interleukin (IL)-2, IL-6 and TNF-α levels were higher than those of group I. MGD and ocular surface parameters were worsened to a greater degree after surgery in group II than in group I (P < 0.050). In group II, IL-6 and TNF-α levels significantly increased at postoperative 1 month, and there were significant correlations between changes in ocular surface parameters and tear cytokines (IL-2, IL-6 and TNF-α; P < 0.050). CONCLUSIONS: The extent to which the MGD grade was aggravated following cataract surgery differed based on preoperative MGD grade. Preoperative MGD and ocular surface status should be carefully evaluated.