Anterior segment changes after pars plana vitrectomy with silicone oil tamponade and after silicone oil evacuation using anterior segment optical coherence tomography

Purpose The aim of this study was to evaluate the changes in intraocular pressure (IOP) and anterior chamber parameters induced by pars plana vitrectomy (PPV) with silicone oil (SO) 1000cs tamponade by using anterior segment optical coherence tomography (AS-OCT) before PPV, post-PPV, and post-SO evacuation. Patients and methods This prospective observational study included 30 patients with rhegmatogenous retinal detachment and proliferative vitreoretinopathy grade B or C who were treated by PPV with SO 1000cs as a tamponade. The IOP was measured and AS-OCT was done before PPV, post-PPV at 1 week and at 1 and 3 months, and post-SO evacuation at 1 week and at 1 month. The outcome measures post-PPV and post-SO evacuation included the changes in IOP, anterior chamber angle, angle opening distance at 500 µm (AOD 500), and trabecular iris space area at 500 µm (TISA 500) compared with the corresponding values before PPV. Results There were statistically significant IOP ineases at all postoperative follow up visits ( P <0.001) which correlated positively with ineased central corneal thickness at 1 week and at 3-month post-PPV ( r =0.28, P =0.04 and r =0.30, P =0.03, respectively). There were significant ineases in the anterior chamber angle in all quadrants at 1 week and at 1 and 3 months post-PPV ( P <0.001) with no significant changes at 1 week post-SO evacuation, while there was a significant inease at 1 month post-SO evacuation except in the superior quadrant ( P <0.001 and 0.09, respectively). There were significant ineases in all quadrants of the AOD 500 and the TISA 500 at 1 week and at 1-month post-PPV ( P <0.05). One week post-SO evacuation, there were significant deeases in all quadrants of the AOD 500 and the TISA 500 except the temporal AOD 500 and the inferior TISA 500 ( P <0.05, 0.46, and 0.40, respectively) while at 1 month post-SO evacuation, there were significant ineases of all quadrants of the AOD 500 and the TISA 500 ( P <0.05). Conclusion PPV with SO 1000cs tamponade caused IOP rise maximally at 1 week which positively correlated with ineased central corneal thickness. The anterior chamber parameters by AS-OCT ineased significantly during the first month post-PPV, which reached to the preoperative values or deeased in the first week post-SO evacuation, and then all parameters were ineased 1 month post-SO evacuation.