UV-Related Cataract: How Sunlight Clouds the Lens of the Eye

A cataract is a cloudy area that forms in the normally clear lens of the eye, scattering light and progressively impairing vision. It develops gradually, can affect one or both eyes, and is the single largest cause of blindness globally, responsible for roughly 39.6% of blindness cases in 2020 and leaving about 20 million people blind. Prevalence rises steeply with age: in the United States about 68% of people over 80 have cataracts. **Symptoms** include faded or yellowed colors, blurred or double vision, halos around lights, glare and trouble with bright light, and difficulty seeing at night, making driving, reading, and recognizing faces harder over time. **UV as a risk factor:** aging is the dominant cause, but chronic ultraviolet radiation exposure, specifically UVB, is a well-documented contributor. The lens absorbs UVB that the cornea lets through, and over decades this oxidative damage promotes clouding. Studies indicate that wearing sunglasses from an early age can slow cataract development later in life. Other major risk factors include diabetes, smoking, eye trauma, ionizing radiation, and long-term corticosteroid use. **Treatment** is highly effective: there is no drug to reverse a cataract, but surgery to remove the clouded lens and implant an artificial intraocular lens restores vision in the large majority of cases, with about 90% of patients reaching 20/40 vision or better. **Prevention** for the UV component is straightforward, UV400 sunglasses and a wide-brimmed hat. See UV Eye Damage: Why Sunglasses Are Medical Equipment, Not Just an Accessory for the broader UV picture and Pterygium (Surfer's Eye): A UV-Driven Growth on the Surface of the Eye for another chronic UV condition. *General informational content, not medical advice.*