Sunglasses Nepal Altitude UV Guide

Overview

Photokeratitis (snow blindness) is a UV burn of the cornea caused by intense UV radiation reflected from snow and ice. Above 4,500 metres in Nepal, particularly on open glacier or snowfield sections near Everest Base Camp, Kala Patthar, or Thorong La, the UV exposure from reflected snow can cause snow blindness in as little as 30 minutes of unprotected exposure. The condition is extremely painful, causes temporary vision loss, and requires 24-48 hours of rest in darkness to heal.

Standard sunglasses with UV400 rating block UV reaching the eye directly from above. They do not block UV entering from the sides. Above 4,000 metres, wrap-around or glacier-style sunglasses with side shields are required. This is not a preference — it is a medical necessity on snow.

The CE Category 4 lens rating (the highest available) reduces visible light transmission to below eight percent and is appropriate for glacier conditions. Category 3 is adequate for trail use at lower altitudes. Lens darkness is distinct from UV protection — dark lenses without UV coating are worse than light lenses with full UV protection because they cause pupil dilation, admitting more UV.

Julbo, Oakley, and Cébé all produce mountain-specific sunglasses with proper side shields. Julbo Explorer or Vermont models are specifically designed for Himalayan conditions. Budget alternatives exist in Thamel but UV protection quality on cheaply made glasses is unreliable — inspect the CE certification mark on the lens.

FAQ

Q: Can I use ski goggles instead of sunglasses above 5,000 metres?
A: Yes. Ski goggles provide excellent UV protection and full peripheral coverage. They are less practical for general trekking due to poor ventilation but ideal for pass crossings in high wind and cold.

Q: Do prescription sunglasses work at altitude?
A: Yes, as long as they are prescription glacier glasses with side shields. Many major optical centres offer prescription glacier glasses.