Equine Recurrent Uveitis (ERU). ERU, also known as moon blindness, iridocyclitis, or periodic ophthalmia is a chronic immune-mediated disease characterized by recurrent inflammation within a portion of the eye called the uvea. Just one or both eyes can be affected with this condition. These episodes of inflammation are followed by periods of quiescence lasting weeks to even years. In the United States, ERU has an estimated prevalence of 2-25% and is the most common cause of blindness in the horse. To learn more about this condition, including causes, treatment, and prognosis, click here.
