The medical terms for the rather trivializing term snow blindness are actinic keratosis and photokeratitis. It is damage to the cornea of the eye caused by strong UV radiation, which can typically occur when staying in the snow at high altitudes or e.g. B. by observing the electric welding with unprotected eyes. Depending on the severity of the burns on the cornea, snow blindness can be extremely painful and cause a foreign body sensation in the eye. In more severe cases, immediate ophthalmological treatment is recommended.
What is snow blindness?
The two medical terms actinic keratosis and photokeratitis indicate damage to the cornea by radiation or by exposure to light. The cornea seals the eyeball from the outside and performs important functions for vision, such as refraction and the unclouded passage of incident light rays. See bestitude for Meaning of Dental Fear.
The outermost layer of the cornea, which – similar to “normal” skin – is constantly renewed, is always wetted with tear fluid in order to be able to perceive its functions. If the UV radiation is too strong, the outermost layers of the cornea can actually be “burned”, which then fulfills the criteria for snow blindness.
Since the cornea of the eyeball is criss-crossed by numerous nerve endings, damage to the cornea as a result of UV radiation can lead to severe pain and extreme sensitivity to light after a latency period of 3 to 12 hours.
The unprotected eyes tolerate daylight and sunlight (not directly in the eyes) in a normal snow-free environment without suffering damage. An increased UV component in sunlight can lead to repairable, but also irreparable damage to the cornea.
The cornea absorbs much of the UV-A and UV-B content of sunlight, protecting the retina and particularly the macula at the back wall of the eyeball, the small area of the retina that allows us to see color and see clearly. If the UV-B component in the incident light becomes too strong, the uppermost layers of the cornea swell up like edema and the dying cells are eroded in an uncontrolled manner.
This process is comparable to a mechanical injury to the cornea. An increased UV component, to which the eye should not be exposed without protection, occurs above all in the high mountains during skiing, on the sea in southern latitudes and at high altitudes (airplane cockpit).
Symptoms, Ailments & Signs
Exposing your eyes to sunlight for too long can damage them. Snow blindness is roughly comparable to sunburned skin. Instead of the skin on the back or shoulders, the cornea and conjunctiva burn here. The snow reflects the sunlight particularly well. Therefore, the symptoms occur especially after spending time in the snow. Symptoms appear a few hours after unprotected eye contact.
It can take up to twelve hours for the affected person to experience severe pain in their eyes and a foreign body sensation. The patient thinks he has sand in his eyes and feels the urge to rub it out of his eyes. The conjunctiva reddens and swells. The symptoms are roughly comparable to conjunctivitis.
Likewise, the eyes often begin to water. Eyelid spasms are also typical of snow blindness. Since the eyes are particularly sensitive to light, the affected person often closes their eyelids. This happens compulsively. The disease, also known as photokeratitis, can also lead to slight visual disturbances.
In some cases, sunburn on the skin was observed at the same time. The symptoms are usually harmless and subside within two days at the latest. If this is not the case, the ophthalmologist should be consulted.
Diagnosis & History
Red and slightly burning eyes can be a first indication of snow blindness. If the eyes have previously been exposed to increased UV radiation without protection, e.g. B. by skiing in the high mountains or after spending hours at sea, this strengthens the suspicion of snow blindness.
If symptoms worsen, an examination and diagnosis should be carried out by an ophthalmologist. The degree of damage to the cornea can be diagnosed using a slit lamp and fluorescein staining.
Severe cases of photokeratitis can lead to irreversible visual impairment due to scarring of the cornea. If one or more of the following symptoms occur, specialist medical attention should be sought immediately:
Snow blindness or flashing can be associated with severe pain because the nerve endings of the UV-damaged outer cornea are exposed. At the same time, the eyelids cramp so that it is no longer possible to open the eyes. Depending on the severity of the flash, vision loss can last for hours or days.
In order to calm the eyes and, if necessary, treat them with antibacterial agents and thus prevent possible complications, you should definitely see a doctor – even if the symptoms seem to subside quickly. Complications can arise, among other things, from additional inflammation of the cornea. Desquamation of the retina is also possible as a result of a flash, which prolongs the healing process, the painful sensations are prolonged and the ability to see again is delayed.
Without medical treatment, there is a risk of super- or secondary infections. This leads to an additional bacterial infection of the damaged tissue. In the worst case, this in turn can lead to permanent blindness. Complications during the healing phase or additional pain that occurs should always be reported to the doctor treating you so that the treatment measures can be adjusted if necessary.
When should you go to the doctor?
In the event of snow blindness, a doctor should always be consulted. In the worst case, snow blindness can lead to complete blindness of the affected person and therefore make everyday life of the patient significantly more difficult. To prevent further complications and symptoms, the sufferer should contact a doctor at the first sign of snow blindness. A doctor should be consulted if vision is reduced and the conjunctiva becomes red or even swollen. A doctor should be consulted, especially after a stay in snowy areas, if these symptoms occur and do not go away on their own.
In general, visual disturbances are indicative of snow blindness and should be investigated if they occur without a specific reason. As a rule, a doctor should be consulted after two or three days at the latest if these symptoms have not yet disappeared on their own. Snow blindness is treated by an ophthalmologist. In emergencies, however, a hospital can also be visited. The life expectancy of the affected person is not limited by the snow blindness.
Treatment & Therapy
Lighter forms of snow blindness heal on their own after 2-3 days because the top layers of the cornea regenerate themselves through natural replenishment. Similar to the skin, new cells are constantly being supplied to replace the cells that have been shed.
Immediate measures for severe forms of snow blindness are staying in a darkened room, resting in bed and cooling pads on both eyes. In more severe forms of the disease, therapy is aimed at treating pain, preventing infections in the injured cornea and supporting measures to promote the natural regeneration of the cornea. For the treatment of acute pain, a single application of locally effective eye drops is recommended because repeated use of the drops increases the already existing damage to the epithelial layer of the cornea.
If pain persists, systemic pain management by taking common pain relievers such as ibuprofen and others can provide relief. Anti-inflammatory and pain-relieving eye drops can also be used. Disinfecting eye ointments containing antibiotics can be used to prevent superinfections on the cornea.
The best protection against snow blindness is provided by suitable sunglasses that almost completely filter out UV light up to 380 nm and also filter out protection in the violet and blue range up to around 480 nm. Glasses that meet this requirement are marked with UV-400. Glasses offer good protection for the other wavelength ranges if the light transmittance is 2% – 8% in the blue range, 10% – 40% in the red to green range and less than 50% in the infrared range (above 780 nm).
Follow-up care by an ophthalmologist is necessary and even indispensable for snow blindness. Severe disease progression can lead to irreversible damage to the cornea and conjunctiva. Because of such dangers alone, medical follow-up care is essential to ensure that the affected person’s eyesight is preserved. Professional aftercare is necessary just to relieve the painful symptoms.
The direct influence of particularly intense UV radiation triggers the symptoms. In mild cases, no permanent damage remains. A follow-up check is nevertheless advisable in order to check the completed healing process again. In the future, the patient can take care of himself by avoiding bright light sources.
A pair of sunglasses can help with this. Another flare-up is prevented. In this case, prevention makes more sense than follow-up care. If there is no noticeable improvement after two to three days, the ophthalmologist will arrange for further examinations. The aim is to determine which eye disease is actually causing the symptoms.
The healing progress is monitored at the follow-up appointments. Surgery may be required to completely eliminate the condition. Regular checks after the inpatient stay are common in any case. The doctor checks whether the eyes have healed as expected.
You can do that yourself
The best self-help measure for snow blindness is prevention. The risk of flashing is particularly high when doing winter sports in the high mountains. Therefore, when the weather is nice and the sun is intense, you should always wear sunglasses suitable for high mountains or appropriate ski goggles.
Water does not only strongly reflect UV rays when it is frozen. The risk of snow blindness therefore also exists with water sports or boat and ship trips. Even crossing smaller bodies of water on a ferry can be risky in strong sunlight. Good sunglasses should therefore also be worn on these occasions. Safety goggles provided by the staff must be used in solariums, as the risk of damage to the eyes from UV light is particularly high here.
If flashes still occur in the eyes, shadows must be provided immediately and a doctor, or even better an ophthalmologist, must be consulted. If those affected do not have protective goggles with them, they should borrow one for the way to the doctor in order to relieve the injured eyes as much as possible.
The eyes often react to the corneal erosion caused by UV radiation with severe itching, and there is often a foreign body sensation. Nevertheless, under no circumstances should scratching or eye contact be made, as otherwise there is a risk of the damaged cornea becoming inflamed.