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- Jenny Brookes, MBBS FACEM MHPE Emergency Physician
Snow blindness is not a cold or heat injury, but is included because it is a highly debilitating but entirely preventable injury associated with altitude and snow.
Snow blindness is the burning of the front surface of the eye (the cornea) from exposure to ultraviolet (UV) radiation, rather like sunburn damage to the skin. Exposure to UV radiation is increased with altitude and in snow conditions, and reflection of UV radiation onto the eyes from the snow can greatly increase exposure.
Although damage can occur from a short period of exposure (e.g. 60 minutes), symptoms do not occur until 8 to 12 hours after the actual injury, so will not become apparent until later in the day or the following day.
Snow blinded eyes are very painful, feel irritated and gritty, and are sensitive to light. The eyes may water profusely, have swollen lids and the surface of the eye may be red and swollen. Without treatment, the eyes will usually heal themselves over the following 24–36 hours or so. However, the discomfort experienced in the meantime may be severe and render the patient quite incapacitated.
Resting with eyes closed and in a dark environment will give some relief. Cold compresses applied gently to the closed eyes may also help relieve discomfort. Contact lenses should be removed while recovery occurs, and the patient discouraged from rubbing their eyes, which may cause additional irritation.
Painkillers (e.g. paracetamol) or anti-inflammatory drugs (e.g ibuprofen) may assist. Snow blindness is a very distressing condition for the patient and reassurance and explanation should be provided. Full recovery is normal.
Snow blindness is entirely preventable with effective eye protection. Snow goggles and sunglasses should have an Eye Protection Factor (EPF) of at least 10. Protection can be improvised by cutting narrow viewing slits in an opaque piece of foam, cardboard or cloth, and securing it around the eyes.
Even on overcast days, UV exposure can be high and eye protection should be worn.