INCREASED INTRAOCULAR PRESSURE IS A RISK FACTOR FOR UNEXPLAINED VISUAL LOSS DURING SILICONE OIL ENDOTAMPONADE

Purpose: To identify the incidence rate and risk factors for unexplained visual loss associated with silicone oil endotamponade used during primary repair of macula-sparing rhegmatogenous retinal detachments. Methods: This retrospective cohort study included patients undergoing pars plana vitrectomy for primary surgical repair of macula-sparing rhegmatogenous retinal detachments in whom silicone oil endotamponade was used. The primary outcome measure was the incidence rate of unexplained visual loss and identification of risk factors associated with vision loss. Results: Of 1,218 eyes undergoing pars plana vitrectomy for primary retinal detachment repair, 44 eyes were included for analysis. In 9 eyes (20%), an unexplained vision loss occurred. Logistic regression identified increased intraocular pressure (IOP) (prospectively defined as IOP readings during silicone oil endotamponade >21 mmHg on two consecutive visits or >= 25 mmHg at any time during this period) as significant predictor (odds ratio =4.9; P = 0.04) and a classification tree ranked IOP as the most important variable for vision loss. Incidence rate of vision loss in eyes experiencing IOP increase was 4.5 vision loss events per 1,000 days at risk compared with 1 event per 1,000 days in eyes without IOP increase, yielding an incidence rate ratio of 4.5 (95% confidence interval: 1.1-17.9; P = 0.02). Conclusion: Sufficient control of IOP during silicone oil endotamponade for primary retinal detachment repair is warranted to reduce the probability of vision loss.