Chan MMH, et al. - In this retrospective observational study, researchers compared risk factors in individuals with a central retinal vein occlusion (CRVO) in the first eye and a subsequent retinal vein occlusion (RVO) in the fellow eye compared with those with only unilateral CRVO. For this investigation, they assessed medical records of patients who presented to the Duke Eye Center with unilateral CRVO. To identify potential covariates of subsequent development of RVO in the fellow eye, logistic regression models were performed. During a mean ± standard deviation follow-up of 36.7 months ± 38.86 months, 31 of the 287 patients with CRVO in one eye developed an RVO in the fellow eye. Data reported that the conversion rate of unilateral-to-bilateral RVO was 3.4% per year. In the fellow eye, patients using oral pentoxifylline or those with an ischemic CRVO were less probable to develop an RVO. This data can be used to develop a predictive model to evaluate the risk of developing bilateral RVO in unilateral CRVO patients.