Risk of Pseudophakic Cystoid Macular Edema in Eyes With Previous Pars Plana Vitrectomy

Importance: Whether prior pars plana vitrectomy (PPV) independently increases the risk of cystoid macular edema (CME) following cataract surgery remains unknown. Objective: To evaluate associations between prior PPV and incidence of CME after cataract surgery. Design, Setting, and Participants: This retrospective cohort study was conducted using the TriNetX US Network, a multicenter federated electronic health record network from December 2005 to December 2025 including academic and community hospitals in the US. Adults aged 18 years or older who underwent cataract surgery were categorized into those with vs those without a history of PPV (≥6 months prior to cataract surgery), excluding those with preexisting CME or risk factors for CME. Data were analyzed from December 2025 through January 2026. Exposure: History of PPV performed more than 6 months prior to cataract surgery. Main Outcomes and Measures: The primary outcome was the incidence of CME within 30 to 90 days postoperatively, identified by International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) diagnostic codes. Risk ratios (RR) were used to compare outcomes. Propensity score matching was performed for demographic and clinical covariates (age, sex, race, hypertension, hyperlipidemia, diabetes, myopia, retinal detachment [RD] history). Results: After propensity score matching with 615 983 patients undergoing cataract surgery, 7422 patients had a prior PPV. After propensity score matching, among patients with prior PPV, mean (SD) age was 62.0 (11.6) years, and 3623 patients (49.5%) were female; among the non-PPV group, mean (SD) age was 61.9 (12.2) years, and 3625 patients (49.5%) were female. Among 14 636 patients representing 7318 propensity score-matched pairs, CME occurred in 336 of 7318 patients with prior PPV (4.59%) compared with 90 of 7318 non-PPV controls (1.23%) (difference, 3.36%; 95% CI, 2.82%-3.90%; RR, 3.73; 95% CI, 2.97-4.70; P < .001). Elevated CME risk persisted in subgroup analyses evaluating prior PPV for RD (5.65% vs 1.22%; absolute difference, 4.43%; 95% CI, 3.48%-5.38%; RR, 4.62; 95% CI, 3.20-6.67; P < .001), as well as those for non-RD indications (3.99% vs 1.23%; absolute difference, 2.76%; 95% CI, 2.06%-3.48%; RR, 3.26; 95% CI, 2.36-4.50; P < .001). Furthermore, after excluding patients with intraoperative and postoperative complications of cataract surgery, the prior PPV group was still found to have a higher risk of CME (4.59% vs 1.26%; absolute difference, 3.32%; 95% CI, 2.77%-3.88%; RR, 3.63; 95% CI, 2.88-4.58; P < .001). Conclusions and Relevance: Results of this cohort study suggest that eyes with vs without prior PPV have higher incidences of postoperative CME. However, numerous limitations, including dependence on coding-based diagnoses and lack of visual acuity outcomes, preclude determining the role of prophylaxis or monitoring for CME in vitrectomized eyes undergoing cataract extraction.