PURPOSE: To compare the visual outcomes, rate of cystoid macular edema (CME), and additional associated complications in eyes that exhibited zonular dialysis (ZD) during phacoemulsification to a reference group of uneventful phacoemulsification eyes. METHODS: A retrospective multicenter comparative database study. We pooled data from 8 United Kingdom sites between 2003 and 2015. The main outcome measures were the mean postoperative visual acuity (VA) at 12-24 weeks and the rates of CME and additional associated complications. RESULTS: We included 1074 eyes in the ZD group and 112,479 in the reference group. Logistic regression analysis showed that pseudoexfoliation was the strongest associated factor of ZD (OR: 6.1), followed by previous glaucoma surgery (OR: 4.4). Mean logMAR preoperative VA was 0.8 ± 0.6 in the ZD group vs. 0.6 ± 0.5 in the reference group ( CONCLUSIONS: The occurrence of ZD was associated with worse postoperative vision, an increased rate of vitreous loss and PCR, and a higher risk of CME.