AIM: To evaluate the influence of pars plana vitrectomy (PPV) on ocular surface using Keratograph 5M. METHODS: Totally 30 consecutive patients (30 eyes) undergoing primary 23-gauge PPV were recruited in the study. Ocular Surface Disease Index (OSDI) questionnaire was performed. Ocular surface parameters, including tear meniscus height (TMH), noninvasive tear break up time (NITBUT) and bulbar redness score were obtained preoperatively, in 1, 2, 4, 8 and 12wk postoperatively by Keratograph 5M. Correlations between all the clinical parameters were analyzed further. RESULTS: The percentages of both photophobia and gritty within 4wk after PPV were significantly higher than pre-operation, while they decreased to the preoperative levels in both 8wk and 12wk postoperatively. The percentage of sore eyes in the first week postoperatively was significantly higher than pre-operation, but there were no significant differences between the percentages of pre-operation and 2, 4, 8, and 12wk postoperatively. OSDI score increased significantly within 4wk postoperatively, but it returned to the preoperative level in 8 and 12wk. TMH increased with 2wk postoperatively, but there were no significant differences compared with preoperation. Both NITBUT-first and NITBUT-average shortened significantly within 8 weeks postoperatively, but they gradually improved to the preoperative levels in 12wk. Bulbar redness score was significantly higher than the preoperative level within 4wk postoperatively, but it returned to the preoperative level in 8wk. NITBUT-first and NITBUT-average had a significant positive correlation at each visit. TMH had a significant positive correlation with NITBUT-average in the first week postoperatively. CONCLUSION: Keratograph 5M can provide a reliable noninvasive method to assess the influence of PPV on the ocular surface. PPV may cause various changes in both symptoms and signs of ocular surface damages at the early stage, while all these changes will return to preoperative levels gradually in 12wk postoperatively.