High altitude has both short-term and long-term effects on the eyes. The short-term effects include high-altitude retinopathy, change in corneal thickness, and photokeratitis. Long-term effects include pterygium, cataract, and dry eye syndrome.

High altitude can definitely cause a variety of eye problems due to the decreased atmospheric pressure and lower oxygen levels (hypoxia), along with increased ultraviolet (UV) radiation. The most common issue is dry eye syndrome, as the air at high altitudes is significantly thinner and less humid, causing tears to evaporate quickly. More seriously, climbers and high-altitude travelers may experience High-Altitude Retinal Hemorrhages (HARH), where small blood vessels in the retina leak due to the physiological stress of hypoxia; while often asymptomatic, they can cause blurred vision. In 2026, experts also warn about "Snow Blindness" (photokeratitis), which is essentially a sunburn on the cornea caused by UV rays reflecting off snow. At extreme altitudes, some individuals experience temporary changes in their cornea's shape, which can affect vision for those who have previously had LASIK surgery. To prevent these issues, it is critical to wear Category 4 UV-protection sunglasses, stay hydrated, and use lubricating eye drops to combat the harsh, dry environment found in mountainous regions.