Adult-onset vitelliform macular dystrophy (AVMD) is an eye disorder that can cause progressive vision loss. AVMD affects an area of the retina called the macula, which is responsible for sharp central vision. The condition causes a fatty yellow pigment to accumulate in cells underlying the macula, eventually damaging the cells. Some people remain without symptoms throughout their life. Other people with AVMD may slowly develop blurred and/or distorted vision, that can progress to central vision loss over time. In the past, AVMD was believed to be mainly a genetic disorder caused by genetic changes in the PRPH2, BEST1, IMPG1, and IMPG2 genes; however, recent studies focused on genetic testing suggest that the genetic cause for most cases of AVMD has not been found. Sometimes AVMD clearly runs in families in an autosomal dominant manner, but the inheritance is suspected to be more complicated in the majority of cases.