To access the data, click or select the words “Appendix 1.” Forward genetics screening identified an association between a Bicdl1 mutation and mild outer retinal thinning. CRISPR-generated Bicdl1 KI mice confirmed shorter outer segments (10-30% reduction depending on the assay and age) and mild photoreceptor loss, as well as a mild decrease in visual function with age. Transcriptomic analysis suggests increased oxidative phosphorylation and modulation of protein synthesis. (Created in BioRender. 2025) https://BioRender.com/sdz34j3)