The study will assess the rate of change of the area of GA secondary to AMD by measuring FAF in up to 330 participants with GA due to AMD being treated with IONIS-FB-LRx. The study is a Phase 2, double-masked, randomized, stratified, placebo-controlled study conducted at multiple centers. It is an adaptive design in which three dose levels will be evaluated in a subset of participants (Stage 1) and, following an interim analysis, the number of participants in two of the dose cohorts will be expanded (Stage 2).