Acucela Inc., of Seattle, reported findings in Retina: The Journal of Retinal and Vitreous Diseases about the safety and tolerability of ACU-4429, its small-molecule visual cycle modulator, in a single-center, randomized, double-blinded, placebo-controlled, dose-escalation Phase I study. Data from the trial demonstrated a well-tolerated, dose-dependent modulation of the visual cycle using electroretinography.