There are many causes of yellowing of the eyes. The most common one is yellowing of the conjunctiva due to age-related conjunctival degeneration. The conjunctival tissue, due to long-term physicochemical stimulation or metabolic abnormalities, has a tendency to keratinize the exposed areas of the conjunctival epithelium, so the transparency of the bulbar conjunctiva decreases and the elastic fibers of the subepithelial tissue atrophy and gradually disappear, making the bulbar conjunctiva thinner and more fragile, along with age-related pigmentation, so the conjunctiva becomes yellow and sometimes brown in color. Some patients may present with a yellowish-white elevation of the local conjunctiva in the lid fissure area, which may be associated with long-term exposure to smoke and sunlight stimulation later, clinically known as lid fissure, a precursor to pterygium. In the early stages, no treatment is usually necessary, but if you feel that it affects the cosmetic appearance, surgical removal may be considered. In addition, localized brown or tan pigmentation may appear on the conjunctiva, which may be residual pigmentation from foreign body contact or from various metabolic processes. Yellowing of the eyes is also associated with systemic diseases, usually considered to be caused by liver and biliary diseases. Therefore, if you notice a gradual yellowing of the whites of both eyes, and if it is accompanied by yellowing of the skin and yellowing of the urine, it is best to visit a hospital internal medicine department in a timely manner, as it is often seen in jaundice, or bilious hepatitis. The yellowing of the eyes must be examined by the hospital eye and the necessary treatment should be carried out according to different conditions.