[Effects of encircling scleral buckling on the morphology and biomechanical properties of the cornea].

Objective: To investigate the effects of encircling scleral buckle (SB) on corneal biomechanical properties of the cornea and its morphological parameters.

Methods: We prospectively examined twelve eyes diagnosed with vitreous haemorrhage undergoing pars plana vitrectomy (PPV), and fifteen eyes undergoing combined PPV and scleral buckle (PPV/SB) for repair of rhegmatogenous retinal detachment (RRD). Corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF), were measured with an Ocular Response Analyser (ORA) before and 1-month postoperatively. The ORA also determined the values of intraocular pressure (IOPg) and corneal compensated IOP (IOPcc). Finally, four morphological parameters of the cornea were measured with the Orbscan II topographer (Orbtek, Inc.): mean corneal power, thinnest corneal point (μm), and anterior chamber depth (ACD).

Results: CH decreased significantly from 10.2+/-1.7mmHg to 7.6+/-1.1mmHg after PPV/SB (p=0.003), but not after PPV alone (9.8+/-3.2mmHg vs 11.6+/-2.7mmHg, P=.465). CRF did not change significantly after surgery in both groups. IOPg and IOPcc increased significantly in the PPV/SB group (P=.019 and P=.010, respectively) but not in PPV group (P=.715 and P=.273, respectively). Unlike the PPV group, values were significantly higher than IOPg values before (P=.001) and after surgery (P=.003) in the PPV/SB group IOPcc. Neither the PPV/SB group nor the PPV group showed any significant changes in the corneal morphological parameters after surgery (P>.05).

Conclusions: SB surgery leads to a change in the corneal biomechanical properties without altering corneal morphological parameters. It may cause an underestimation error in IOP measurement. PPV may be a less invasive surgical approach for the repair of noncomplex RRD than PPV/SB.