Snow blindness is a painful, transient loss of vision due to overexposure to the sun's Ultraviolet rays. It is medically termed as photokeratitis; where "photo" means light, and "keratitis" means inflammation of the cornea. Photokeratitis can be caused by the reflection of the sun from sand, water, ice, and snow. One may also get snow blindness if they stare at the solar eclipse without any special device. The outcome of the same without taking proper protection of the eyes can be harmful in the long run, resulting in serious corneal damage. Snow can reflect over 80% of the UV rays, so the chances of getting snow blindness at high altitudes with stronger UV rays are relatively higher.

Symptoms of Snow Blindness:

Some snowboarders use the term ‘Sunburned eyes’ to describe Snow Blindness. The symptoms include pain, tearing, redness, swelling, headache, gritty feeling, halos around lights, hazy vision, double vision, and temporary colour change or loss of vision; but are not only restricted to it. Different people have different reactions to snow blindness. Like any sunburn, the effect of this condition isn't felt until hours after exposure. A mild case of snow blindness will make your eyes teary and bloodshot. While a more severe one will make your eyes feel like they are full of sand and may even swell shut.

Vision loss from snow blindness typically resolves in 24 to 48 hours but can take up to 5-7 days to completely recover with good care. The condition doesn't cause actual blindness but can impair your vision considerably, making it unsafe to drive.

Causes of Snow Blindness:

Snow blindness usually occurs at high altitudes on highly reflective snow fields or, rarely with a solar eclipse. Artificial sources of UVB can also cause snow blindness. The sources include sun tanning beds, a welder's arc, carbon arcs, photographic flood lamps, lightning, electric sparks, and halogen desk lamps.

Treatment and Relief:

Photokeratitis and snow blindness normally go away on their own, so treatment is focused on making one feel better as the eyes start to heal. If a person who wears contact lenses faces symptoms of snow blindness, it is advised to take the lenses off immediately and to refrain from wearing them again until the eyes heal completely. Moving away from the sun and getting inside a dark room is the first thing one should do. Sunglasses work wonders for the treatment of this condition as it reduces pain and discomfort.

Doctors often recommend covering both eyes with half-inch-thick pads of soft cloth or gauze bandages. This will protect the eyes from the sunlight and help in reducing irritation caused by eyelid movement. The injury has to be checked at half-day intervals and when one can keep their eyes open comfortably, remove the dressing.

For further relief, one may try out the following:

• Place a cold, dampened washcloth over closed eyes for comfort. To keep the infected eyes well-moistened, use artificial tears. Choosing preservative-free formulations for mild dry eyes help in avoiding sensitive reactions from preservatives. It also reduces the chances of increased blurred vision from drops that are too thick.

• Pain relievers can be taken after proper consultation with an ophthalmologist. It is highly advisable to stick to the dosage instructions. Be sure to check if you are allergic to any of the components.
• Eye-drop antibiotics also work well but use it only after an ophthalmologist recommends it.

It is important to avoid rubbing the eyes as a person heals, for it will only worsen the condition further.

How to Prevent Snow Blindness:

• One can wear sunglasses that guarantee to block the sun's UV rays completely during daylight.
• Sun-sensitive photochromic lenses serve as a convenient alternative.
• For skiing, snowboarding, water sports, or any plan that involves spending long hours outdoor, invest in proper sunglasses that have a wrap-style frame to keep the eyes safe from indirect as well as direct sunlight.
• To be completely safe from the condition, one can also use snow goggles or sports goggles which prevent sunlight from entering through any direction.
• Polarized sunglasses are an ideal fit as they reduce the intensity of reflected glare.

How to protect during the trek:

Treks have various health benefits, but it comes with a fair share of distraction that one needs to be aware of. The treatment for snow blindness is readily available, but ‘prevention is better than cure’. It is important to take measures that would protect your eyes from the harmful UV rays of the sun. UV rays are made up of two components, UVA and UVB; while UVA rays cause serious harm to the retina, UVB rays get absorbed by the cornea. The chances of getting snow blindness are relatively higher during treks. It is mainly due to two reasons:

• The atmosphere layer in the mountains is thin. The density keeps on decreasing with an increase in altitude and reduces the capacity of filtering UV rays. This makes it easier for a person to get snow blindness.
• The intensity of UV rays is higher in places with snow and glacier because they tend to reflect 95% of Ultraviolet rays.

It is very important to have the right kind of eye protection while going on a trek. Sunglasses are an absolute essential. If you are an avid trekker, it is advisable to get UV protected sunglasses custom made by your optician. Do not wear contact lenses when you are trekking. Polarized clips can be used over your daily spectacles. Polarised sunglasses with photochromic lenses can also be used as they reduce the amount of reflected glare. It is not recommended to use gradient sunglasses in snowfields and glacier zones. The tints of colour approved for the lens in such cases are Red-orange, Brown, Amber, and Grey. The ideal percentage of VLT, i.e Visible Light Transmission in a lens depends on the altitude of the trek. VLT is the amount of visible light that passes through a lens. If the trekking adventure involves more snow and glacier, the VLT percentage should be lesser and vice versa.

Measures of Added Protection:

• Anchor straps help in keeping the sunglasses safe when not in use.
• Temple pads give added protection to the temple area and ensure that one doesn’t overstrain themselves from wearing sunglasses at all times.
• Nose grips allow the sunglasses to stay in place, without causing discomfort.
• An anti-fogging coat on your sunglasses will prevent the formation of fog on your glasses and help in maintaining the clarity of vision.

Is Snow Blindness Permanent?

In the majority of the cases, snow blindness is temporary. People suffering from snow blindness start healing with proper treatment and rest. But in some cases, the loss of vision could be permanent if the eyes had been exposed to the reflected light for too long resulting in solar retinopathy.

How Long Does Snow Blindness Take To Go Away?

The speed of recovery of a patient is dependent on various factors. To start with, the amount of time the eyes were exposed to the UV rays without any protection plays a very important role in determining the pace of recovery. The intensity of the UV ray matters, as with lesser strength UV rays the damage won’t be serious and could be healed easily. While in the case of direct contact with strong Ultraviolet rays, the healing process is relatively time-consuming.

People having mild snow blindness may recover within 24 to 48 hours with accurate treatment and adequate rest. But for normal to relatively serious conditions of snow blindness, it takes around 5 to 7 days for a complete recovery with good treatment. Nevertheless, in very extreme cases, the damage caused could be everlasting.

If you are a frequent trekker or have been planning to go on a trek, you must consider implementing the necessary safety measures. Reading well about the trek before deciding on it will ensure a better understanding of the journey and the preparations required.