Background Dry eye is a common condition affecting many patients after different ocular surgeries. The recent technique of pars plana vitrectomy as 23- or 25-G vitrectomy has an overt advantage over the traditional 20-G vitrectomy in causing less damage to the conjunctival tissue. Patients and methods This is a prospective randomized study, which enrolled 16 eyes that underwent traditional 20-G vitrectomy (group 1) and were compared with 15 eyes that underwent 23-G vitrectomy (group 2). Preoperative and postoperative (first day, first week, first month, and third month) Schirmer 1 (ST1) test and tear break-up time test (TBUT) were used to evaluate the tear film amount and quality. The postoperative symptoms and signs of dry eye were observed and compared in both groups. Results No significant differences were found between the two groups regarding the mean age, sex distribution, comorbidities, and preoperative ST1 or TBUT tests. Both groups experienced excess tears at the first postoperative day. At the end of the first postoperative month, group 1 showed significantly lower values of ST1 and TBUT tests than group 2 (P=0.002 and 0.05 for both tests). Patients in the 23-G group reported significantly less incidence of ocular pain and red eye at the first week and first month after surgery. Conclusion 23-G vitrectomy has less damaging effects on the conjunctival tissue, reflected as less reduction in the tear film quantity and lower rates of dry eye, than the traditional 20-G method.