Purpose: This study aimed to investigate the impact of delayed retinal clinical care during the COVID-19 pandemic on the severity of proliferative diabetic retinopathy (PDR) and drivers of follow-up delay. We compared disease severity and follow-up rates of PDR patients requiring vitrectomy to those managed nonsurgically, and identified factors associated with need for vitrectomy. Methods: The study included 739 patients diagnosed with PDR between January 1, 2018, and March 4, 2021, categorized into two groups based on outcome: vitrectomy nonvitrectomy. Statistical methods such as t-tests and chi-square tests were used to analyze differences in disease severity and follow-up rates before and after COVID-19 shutdown. A multivariate regression evaluated factors leading to vitrectomy by comparing initial ETDRS (Early Treatment of Diabetic Retinopathy Study) DR staging, disease stability, DR progression, proliferative complications, appointment intervals, follow-up variance, rescheduling rate, and no-show rate. Results: Of the 739 patients, 202 required vitrectomy, 537 were managed nonsurgically. The vitrectomy group had more severe or unstable disease before shutdown. The interval between patient visits preshutdown was 29.76 ± 45.11 days in the vitrectomy group and 40.23 ± 56.73 days in the nonvitrectomy group (p < 0.001). Both groups experienced a significant increase in appointment intervals after shutdown, with the vitrectomy group having a greater increase. Both groups had significantly increased rescheduling rate and minimally increased no-show rate. Patient-directed rescheduling was the main driver of appointment delays. Disease factors, such as tractional retinal detachment and higher ETDRS DR staging, increased the odds of vitrectomy, while appointment burden and follow-up variability had a minimal impact. Conclusions Patients with more severe PDR and greater delay in appointments due to the pandemic were more likely to require vitrectomy for proliferative complications. Patient-directed rescheduling was identified as the main driver of care delays, as opposed to clinic-directed rescheduling. This study highlights the importance of maintaining regular follow-up appointments for PDR patients during pandemics.