CR2-fH rescues ultrastructural changes in the outer retina in mice following cigarette exposure. Electron micrographs of the outer retina obtained from age-matched mice after 6 months of cigarette smoke exposure (CSE) or room air followed by 3 months of treatment with PBS (B) (smoke + PBS), CR2-fH (C) (smoke + alternative complement pathway inhibitor, CR2-fH), or 3 additional months of room air (A) (control, never smokers) were compared. While all animals had the same number of photoreceptors per row (∼9), the nuclei were more densely packed in the smoke + PBS– when compared to the control and CR2-fH–treated animals. IPL, inner plexiform layer; INL, inner nuclear layer; OPL, outer plexiform layer; ONL, outer nuclear layer; IS, inner segments; OS, outer segments.