Twelve-Months Outcomes and Optical Coherence Tomography (OCT) Biomarkers After Intravitreal Dexamethasone Implant in Pseudophakic Eyes with Post-Vitrectomy Cystoid Macular Edema (CME), Refractory to Medical Therapy

Background: To evaluate the incidence of postsurgical cystoid macular edema (PCME) after small-gauge pars plana vitrectomy (PPV) for different retinal pathologies and to assess the role of optical coherence tomography (OCT) biomarkers to guide treatment decision in patients with PCME, refractory to medical therapy. Materials and Methods: Medical records of consecutive pseudophakic patients, who underwent PPV for different retinal pathologies, were retrospectively evaluated in this single center, uncontrolled study. The incidence of post-PPV CME was assessed in this population. Eyes that presented with post-PPV CME within the first 2 months after surgery were considered for further evaluation. A minimum follow-up of 12 months, history of previous cataract surgery performed not earlier than 1 year before PPV, the availability of full clinical and OCT data at 1, 3, 6, 9 and 12 months after PPV, constituted the minimal requirements to be included in the 12-months assessment. Mean best corrected visual acuity (BCVA; LogMAR) together with mean central macula thickness (CMT; m) change, and response to different treatments (medical therapy and dexamethasone intravitreal implant) were evaluated. The impact of specific clinical and structural OCT biomarkers on the exposure to dexamethasone (DEX) intravitreal treatment was assessed. Eventual ocular and non-ocular adverse events, potentially related to the treatment, were investigated as-well. Results: Of 346 pseudophakic patients (352 eyes) enrolled in the study, 54 (54 eyes) developed CME within the first 2 months after PPV (incidence of 15.3%). After the exclusion of 6 subjects, the remaining 48 pa-tients were dimed eligible for the 12-months analysis. Preoperative mean BCVA (1.44 ± 0.99 LogMAR) sig-nificantly improved to 0.32 ± 0.37 LogMAR at 12 months (P< 0.001). Mean baseline CMT of 347 (± 123.5) m, significantly decreased to 290 m (± 80.4; P=0.003) by the end of the FU. Twenty-five eyes (52%) re-quired one or more DEX intravitreal implants for CME, refractory to topical therapy. The correlation analy-sis disclosed the existence of significant correlations between mean CMT values at different time points of the FU. Additionally, patients who required intravitreal therapy at months 3 and 9, were more likely to present with the following features at 1 month OCT: intraretinal fluid (IRF), disorganization of inner retinal layers (DRIL), disorganization of outer retinal layers (DROL) and hyperreflective foci (HRF). No major safe-ty issues arose. Conclusion: Topical therapy alone can be a valuable option for post-PPV CME in approximatively 50% of pa-tients. Significant visual acuity recovery and CMT reduction at 12 months, demonstrated DEX intravitreal implant can be a safe and effective second-line treatment for pseudophakic patients with post-PPV CME, refractory to medical therapy. The presence of specific OCT biomarkers may indicate a more severe CME that might benefit from the intravitreal therapy.