Tx cause. Depends on the cause. If from "pink eye"-time & maybe antibiotic eye drops. If from allergies-tx w/ allergy med. If from subconjunctival hemorrhage (tiny broken blood vessel in 1 eye only)-heals on it's own w/in 2 wks. If from corneal abrasion or ulcer-need to see eye doc for tx. If from lack of sleep-sleep more. If not improving w/ initial tx-pls see your doc. Good luck!