PURPOSE: To evaluate surgically induced changes in corneal viscoelastic properties of patients undergoing 23-gauge transconjunctival sutureless vitrectomy (23-G TSV). METHODS: The study group consisted of 29 eyes of 29 patients undergoing 23-G TSV. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), corneal compensated intraocular pressure (IOPcc) and central corneal thickness (CCT) were measured by ocular response analyser (ORA), preoperatively and 1 and 3 months postoperatively. Goldmann applanation tonometry (GAT) was also performed in the same time periods. The ORA measurements before and after the surgery were compared statistically. In addition, the ORA measurements of a control group comprising of 29 normal subjects were also compared with the preoperative measurements of the patient group. Finally the relationship between the CH values and the CCT and GAT values was also assessed. RESULTS: The preoperative ORA measurements of the study group were similar to those of the control groups' (p > 0.05 for all). In the study group, mean CH decreased and mean IOPcc increased significantly at 1 month compared with their respective preoperative values (p = 0.04 and p = 0.03, respectively). However CH and IOPcc measurements at 3 months were similar to the preoperative measurements (p > 0.05). Mean CRF, IOPg, GAT and CCT measurements did not change significantly during the study period (p > 0.05). CH was weakly correlated with CCT preoperatively, 1 and 3 months postoperatively (r = 0.33, r = 0.33, r = 0.43, p < 0.05 for all, respectively). There was also a weak but significant correlation between CH and GAT preoperatively (r = 0.42, p = 0.008), 1 month postoperatively (r = 0.36, p = 0.03), 3 months postoperatively (r = 0.40, p = 0.01). CONCLUSION: Corneal viscoelastic properties are not significantly influenced in the late postoperative period by 23-G TSV which is a minimal invasive vitreoretinal surgical technique.