OPN1SW encodes short-wavelength-sensitive opsin, a G protein-coupled photoreceptor responsible for blue light detection in cone photoreceptors 1. The protein functions as a visual pigment by binding cis-retinal to absorb visible light and activate phototransduction cascades 2. OPN1SW is essential for maintaining cone outer segment organization and ensuring correct localization of retinal membrane proteins, particularly in the ventral retina 3. Expression is regulated by RORβ (retinoid-related orphan receptor beta) in cooperation with CRX during postnatal cone development 3. OPN1SW evolution is shaped by nocturnal light environments; species in open-canopy forests experience stronger purifying selection to maintain functional SWS cones compared to closed-canopy species 4. Metabolically, OPN1SW+ cones display enriched fatty acid biosynthesis compared to other cone subtypes 1. Loss-of-function mutations cause tritan color blindness through haploinsufficiency or splicing defects 5. Gene therapy targeting OPN1SW-deficient cones shows promise for blue cone monochromacy (BCM) treatment, with early intervention (≤2 months) achieving sustained functional rescue for at least 8 months, while delayed treatment (≥5 months) shows significantly reduced efficacy 6. Rare missense mutations like p.G141S and p.R144C disrupt opsin structure and function 7.