To evaluate the risk of a rhegmatogenous retinal detachment (RRD) in the fellow eye using posterior hyaloid status as determined by OCT at the time of initial RRD.Retrospective chart review.Patients with a diagnosis of RRD.Posterior hyaloid status-presence or absence of a posterior vitreous detachment (PVD)-in both eyes at the time of initial RRD was determined by OCT imaging. Baseline characteristics, including lattice degeneration, refractive error, prior ocular laser procedures, lens status, and family history of RRD, were recorded.The main outcome measures were the development of fellow-eye RRD and the time to fellow-eye RRD. In addition, OCT imaging was used in those fellow eyes with a visible posterior hyaloid to document whether a PVD developed during follow-up and time to such an event.A total of 1049 patients with an RRD were followed up for an average of 5.7 ± 0.3 years. Overall, 153 patients (14.6%) received a diagnosis of bilateral sequential RRD during this follow-up period. OCT images were available for 582 fellow eyes; PVD was noted in 229 fellow eyes (39.3%), and an attached hyaloid was noted in 353 fellow eyes (60.7%). An RRD occurred in 7 fellow eyes (3.1%) with a PVD at presentation. Within the cohort of fellow eyes with an attached hyaloid, 28 eyes (7.9%) demonstrated an RRD during follow-up; however, when evaluating only those in which a PVD developed during follow-up, 23.7% of such eyes were found to have an RRD as well. At the time of PVD development in the fellow eye, an additional 21 eyes (17.8%) were noted to have a retinal tear that was treated without progression to RRD.OCT imaging of the fellow eye at the time of presentation with an RRD offers a significant amount of information regarding risk stratification for RRD in this eye. Patients noted to have a completely detached posterior hyaloid are at a significantly lower risk of RRD than those with a visible posterior hyaloid, who need to be monitored closely at the time of PVD development.The author(s) have no proprietary or commercial interest in any materials discussed in this article.