Surgically induced changes in corneal biomechanical parameters after 23 gauge pars plana vitrectomy

Surgically Induced Changes in Corneal Biomechanical Parameters After 23 Gauge Pars Plana VitrectomyPurpose: To evaluate surgically induced changes in corneal biomechanical properties of patients undergoing 23 gauge transconjunctival sutureless vitrectomy (23 G TSV).Methods: We prospectively examined 29 eyes of 29 patients who underwent 23 G TSV. Corneal biomechanical properties, including corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (İOPg) and corneal compensated intraocular pressure (İOPcc) were measured by Ocular Response Analyser (ORA) before, 1 and 3 months postoperatively. Topographic mesaurements were obtained and recorded at the same time periods. Taking these mesaurements into account, induced astigmatism values were determined. The ORA and topographic measurements before and after the surgery were compared statistically.Results: There were no statistically significant difference between the preoperative and postoperative mean CRF and IOPg measurements in the study group. Mean CH was 9.12±1.83 mmHg preoperatively, 8.15±2.16 mmHg 1 month and 8.55±1.61 mmHg 3 months postoperatively (p=0.04, p=0.11 and p=0.25, respectively). The mean IOPcc was 17.72±6.23 mmHg preoperatively, 20.28±6.50 mmHg 1 month and 18.74±5.76 mmHg 3 months postoperatively (p=0.03, p=0.45 and p=0.23, respectively). There were significant differences between preoperative and 1-month postoperative mean CH and IOPcc measurements (p=0.04 and p=0.03, respectively). There were no statistically significant difference between the preoperative and postoperative mean Sim K values. Surgically induced astigmatism was 1.98 ± 1.20 D and 3.22 ± 1.77 D at postoperative 1 and 3 months respectively.Conclusion: Although CH decreased and IOPcc increased in the early postoperative period, the parameters reached preoperative values by 3 months postoperatively, showing that corneal biomechanical properties are not influenced by 23 G TSV which is a minimal invasive vitreoretinal surgical technique.Keywords: corneal hysteresis, corneal resistance factor, ORA, vitrectomy.