Prognostic factors of postoperative intraretinal cystoid spaces after primary pars plana vitrectomy for vitreomacular traction

PURPOSE: To study the anatomical and surgical prognostic factors related to developing postoperative intraretinal cystoid spaces (ICS) six months after 25-gauge pars plana vitrectomy (PPV) for vitreomacular traction (VMT). METHODS: The study is a retrospective case series of patients presenting with VMT treated primarily with PPV. All patients underwent 25-gauge PPV by the same retina surgeon. Intra-operative parameters were all recorded. Postoperative visual acuity (VA), foveal thickness, and ICS were collected over six months of follow-up. ICS were defined as hyporeflective cysts divided by hyperreflective septa on optical coherence tomography (OCT). Patients with ICS persistence 3 months postoperatively received topical treatment extension. The primary outcome measure was odds of preoperative ICS in patients with postoperative ICS compared to controls. Secondary outcome measures were odds of presence of an attached hyaloid to the optic disc, presence of pseudophakia, the use of intra-operative air, and the use of more than one intra-operative indocyanine green (ICG) injections in patients with postoperative ICS compared to controls. RESULTS: Two hundred and eighty treatment-naïve patients with preoperative diagnosis of epiretinal membrane (ERM) were reviewed. Thirty patients with VMT, confirmed both preoperatively on OCT and intra-operatively, were included. Postoperatively, 40% (n = 12) presented with ICS at 6 months. Among these, 83% (n = 10) had ICS prior to PPV. Patients presenting with preoperative ICS were significantly more at risk of having persistent ICS postoperatively (P < 0.05). The following factors did not statistically affect ICS occurrence: optic disc hyaloid attachment status, phakia/pseudophakia, intra-operative air vs. sulfur hexafluoride (SF(6)), and the number of intra-operative ICG injections. CONCLUSIONS: Our data demonstrate a predictive relationship between the occurrence/persistence of ICS post-PPV for VMT and the initial foveal status. Specifically, having preoperative ICS is a major risk factor for its persistence postoperatively. Our data highlight the pathophysiological importance of the vitreous phase and its effect on visual prognosis.