 This multicenter, randomized, single-masked, sham injection-controlled study will investigate the exposure-response and safety of lampalizumab administered intravitreally every 2 weeks Q2W or every 4 weeks Q4W for 24 weeks in participants with geographic atrophy GA secondary to age-related macular degeneration AMD. A safety run-in assessment will be conducted prior to initiating enrollment in the randomized study. 