Influence of pterygium excision surgery on corneal biomechanical properties

Purpose To evaluate biomechanical corneal changes after pterygium excision surgery. Methods Prospective, interventional study in which 22 patients with unilateral pterygium were enrolled. Patients underwent pterigyum excision surgery with conjunctival autograft transplantation. The following corneal biomechanical properties were studied using Ocular Response Analyzer (ORA), preoperatively and postoperatively: Corneal Resistance Factor (CFR), Corneal Hysteresis (CH), Goldman correlated intraolcular pressure (IOPg) and Corneal Compensated IOP (IOPcc). Results CRF increased after pterygium excision surgery. Nevertheless, CRF returned to normal values at day 30. There was a decrease in CH parameters at day 7 and at day 30 compared with preoperative values. There was an increase in IOP, IOPg and IOPcc postoperatively. Conclusion CH decreases after pterygium surgery probably because of the elimination of a biomechanical reinforcement provided by the fibrovascular tissue that invades the anterior stroma. The postoperative decrease in CH could influence the IOP measure, which could be infraestimated using the Golman applanation technique. ORA postoperavtive exploration provides more precise IOP values.