Functional recovery following vitreoretinal surgery

The general aim of this thesis was to evaluate functional outcome following vitreoretinal surgery for idiopathic epiretinal membranes (iERM) and rhegmatogenous retinal detachment (RRD). Idiopathic epiretinal membrane Pars plana vitrectomy with removal of the iERM is considered to be the standard treatment, but the indication and timing of surgery has not been standardized and clinical outcome varies. Individual visual outcome is hard to predict. Therefore, we provide a systematic review of the literature on potentially predictive factors for postoperative visual acuity in iERM. The integrity of the inner segment / outer segment junction on optical coherence tomography (OCT) was probably, and central foveal thickness was not associated with postoperative visual acuity. The severity of metamorphopsia, the integrity of cone outer segment tips on OCT, and fundus autofluorescence are potential promising predictive factors. In a retrospective cohort study, we found that preoperative visual acuity was correlated to postoperative visual acuity after 3 months. A prospective cohort study yielded a prognostic model including preoperative visual acuity, the presence of an iERM or vitreomacular traction in the fellow eye, and hyperfluorescence on fundus autofluorescence which could explain 71.8% of the change in visual acuity 6 months following surgery. Rhegmatogenous retinal detachment We address the clinical and functional findings, and the pathophysiology of unexplained visual loss following silicone oil (SO) tamponade. In general, the visual prognosis after surgery for RRD with an attached macula is very good. In certain types of RRD, intraocular SO is indicated as an intraocular tamponade. Recently, a number of case series were published on a profound and unexplained visual loss that occurred during SO tamponade or following SO removal. Hitherto, the underlying pathophysiology is unknown. In a retrospective cohort of patients with a macula-on RRD treated by either SO or gas tamponade, an unexplained visual loss was found in 30% of the eyes treated by SO and the duration of tamponade was identified as the only risk factor. Microperimetry revealed a specific deep and small central scotoma in eyes suffering from silicone oil related visual loss (SORVL) and therefore could be valuable in the diagnostic work-up of low visual acuity following the use of SO. In a prospective cohort study, we demonstrated that this central scotoma could also be observed in eyes following SO tamponade for a macula-off RRD and that subtle abnormalities on microperimetry were observed in some eyes following SO tamponade for macula-on RRD. The ganglion cell layer (GCL) together with the inner plexiform layer (IPL) on OCT was thinner in all patients following SO tamponade compared to gas tamponade. We aimed to localize the functional deficit of SORVL by means of electrophysiology. It was found that multifocal electroretinograms were consistently abnormal in all eyes, indicative of retinal damage. We tested the hypothesis that potassium accumulates in the fluid around the SO bubble (retro-oil fluid) leading to SORVL. Potassium was not increased in retro-oil fluid, which makes the ‘potassium accumulation’ hypothesis unlikely. Magnesium concentrations were significantly lower in eyes with SO tamponade.