Purpose: To assess the treatment effect of AVD-104 in eyes with geographic atrophy (GA) secondary to dry age-related macular degeneration (AMD) by multifocal electroretinography (mfERG) and evaluate mfERG as a potential clinical endpoint in dry AMD studies. Methods: This prospective case series included 6 patients enrolled in part 1 of the phase 2/3 SIGLEC clinical trial, all of whom were diagnosed with advanced bilateral GA. Subjects received a single intravitreal injection of AVD-104 in the study eye. At a screening visit, baseline, and months 1, 2, and 3, mfERG testing and best-corrected visual acuity (BCVA) were collected in the study eyes. mfERG testing was also collected at a screening visit, baseline, and month 3 in fellow eyes. We analyzed the overall N1-P1 response density, overall P1 implicit time, junctional N1-P1 response density, and junctional P1 implicit time at each visit. Results: After AVD-104 treatment, the largest improvements in mean overall N1-P1 response density and junctional N1-P1 response density occurred at month 2, with gains of 17.1% (P = .47) and 40.1% (P = .01), respectively. Five of 6 study eyes achieved a greater than 20% gain in mean junctional N1-P1 response density at month 2, and 3 study eyes maintained more than a 20% gain at month 3. Mean BCVA also improved incrementally at each follow-up visit, reaching +6.0 letters over baseline at month 3 (P = .04). Conclusions: mfERG and BCVA data supported the benefit of AVD-104 treatment in eyes with GA and revealed the potential to recover retinal function in the junctional zone 2 months after treatment.