What is snow blindness?
The two medical terms actinic keratosis and photokeratitis indicate damage to the cornea due to radiation or light radiation. The cornea closes the eyeball outwards and takes on important functions for seeing how light refraction and unclouded passage of the incident light rays was.
The outermost layer of the cornea, which is constantly renewing itself - similar to "normal" skin - is always moistened with tear fluid in order to be able to perform its functions. Excessive UV radiation can literally "burn" the outermost layers of the cornea, which then complies with snowblindness.
Since the cornea of the eyeball is penetrated by numerous nerve endings, damage to the cornea due to UV radiation after a latency period of 3 to 12 hours can lead to severe pain and extreme photosensitivity.
The unprotected eyes tolerate daylight and sunlight (not directly in the eyes) in a normal snow-free environment, without damage. An increased UV component in the sunlight can lead to reparable, but also irreparable damage to the cornea.
The cornea absorbs a large portion of the UV-A and UV-B content in the sunlight, protecting the retina and, in particular, the macula on the posterior wall of the eyeball, the small area of the retina that allows us to see and see colors, If the UV-B content in the incident light becomes too strong, the uppermost layers of the cornea become edematous and uncontrolled erosion of the dying cells occurs.
This process is comparable to that of mechanical corneal injury. Increased UV content, to which the eye should not be exposed unprotected, it comes especially in the high mountains for skiing, at sea in southern latitudes and at high altitudes (aircraft cockpit).
Symptoms, complaints & signs
If the eyes are exposed to sunlight unprotected for too long, they can be damaged. Snow blindness is comparable to the sunburn of the skin. Instead of the skin on the back or shoulders burn here cornea and conjunctiva. The snow reflects the sunlight especially strong. Therefore, the complaints occur especially after stays in the snow. The symptoms appear a few hours after unprotected eye contact.
It can take up to twelve hours for the person to feel great pain in their eyes and feel a foreign body sensation. The patient thinks he has got 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 start to tears. Typical for the snow blindness is also a Lidkrampf. Since the eyes are particularly sensitive to light, the affected person often closes the eyelids. This happens compulsively. The disease, also known as photokeratitis, can also lead to mild visual disturbances.
In some cases, sunburn was also observed on the skin at the same time. The complaints are usually harmless and resolve within two days at the latest. If this is not the case, the ophthalmologist should be consulted.
Diagnosis & History
Reddened and slightly burning eyes can be a first indication of snow blindness. If the eyes were previously exposed unprotected to increased UV radiation, z. B. by skiing in the high mountains or after hours at sea, which substantiates the suspicion of snowblindness.
For more severe complaints, an examination and diagnosis should be made by an ophthalmologist. How severely damaged the cornea can be diagnosed by slit lamp and fluorescein staining.
Severe cases of photokeratitis may result in irreparable visual impairment due to scarring in the cornea. If one or more of the following symptoms occur, specialist care should be sought immediately:
Snow blindness or blinding 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 burn, there may be hours or days of vision loss.
To calm the eyes and if necessary to treat antibacterial and thus prevent possible complications, the doctor should be consulted - even if the symptoms seem to fade quickly. Among other complications may be additional inflammation of the cornea. Retinal degeneration is also possible as a result of burn-in, prolonging the healing process, prolonging the painful sensations, and delaying the recovery of vision.
Without medical treatment there is a risk of super or secondary infections. This leads to an additional bacterial infection of the damaged tissue. This in turn threatens in the worst case, a permanent blindness. Complications during the healing phase or additional pain should always be reported to the attending physician, so that the treatment measures can be adjusted if necessary.
When should you go to the doctor?
In case of snow blindness, a doctor should always be consulted. In the worst case, the snow blindness can lead to complete blindness of the person concerned and therefore make the daily routine of the patient significantly more difficult. To prevent further complications and discomfort, the affected person should turn to a doctor at the first sign of snowblindness. A doctor should be consulted if it comes to a reduced visual strength and the conjunctiva reddens or even swells. In particular, after a stay in snowy areas, a doctor should be consulted if these symptoms occur and do not disappear on their own.
In general, visual disturbances indicate snowblindness and should be investigated if they have occurred without any particular reason. As a rule, a doctor should be consulted after two or three days at the latest, if these symptoms have not disappeared by themselves. The 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
Easier forms of snow blindness heal after 2 - 3 days by itself, because the uppermost layers of the cornea regenerate automatically by natural subsequent delivery. Similar to the skin, newly formed cells are constantly replenished for the rejected cells.
As an emergency in stronger forms of snow blindness stay in a darkened room, bed rest and cooling pads are announced on both eyes. In more severe forms of the disease, the therapy aims to treat pain, prevent infection of the injured cornea and supportive measures to promote natural regeneration of the cornea. For the acute treatment of pain, only a single application of locally effective eye drops is recommended because a repeated application of the drops enhances the already existing damage to the epithelial layer of the cornea.
For persistent pain, systemic pain relief can be obtained by taking common pain relievers such as ibuprofen and other relief. Accompanying the application of anti-inflammatory and analgesic eye drops can be made. To prevent superinfections on the cornea, disinfectant ophthalmics containing antibiotics may be considered.
The best protection against snow blindness is offered by suitable sunglasses, which filter out UV light almost completely up to 380 nm and also filter out protection in the violet and blue areas up to about 480 nm. Glasses meeting this requirement are labeled with UV-400. For the remaining wave ranges, glasses provide good protection when the light transmission in the blue range is 2% - 8%, in the red to green range 10% - 40% and in the infrared range (above 780 nm) below 50%.
A follow-up care by an ophthalmologist is necessary in snow blindness and even indispensable. Severe illnesses can lead to irreversible damage to the horny and conjunctival membranes. Just because of such dangers a medical follow-up must necessarily be made so that the eyesight of the person concerned is preserved. Just for the relief of painful complaints, a professional follow-up care is needed.
The direct influence of particularly intense UV radiation triggers the symptoms. With mild gradients, no permanent damage remains. A follow-up is still advisable to re-examine the completed healing process. In the future, the patient can take care of themselves by avoiding bright light sources.
Here, a pair of sunglasses is supportive. Another disease spurt is prevented. Instead of aftercare provision is useful in this case. If there is no noticeable improvement after two to three days, the ophthalmologist will arrange further examinations. It should be determined which eye disease actually underlies the symptoms.
The healing progress is monitored at the follow-up appointments. You may need surgery to completely eradicate the disease. Regular check-ups after hospitalization are always common. The doctor checks if the eyes could heal as expected.
You can do that yourself
The best self-help measure is snow blindness in precaution. The risk of blinding is especially great for winter sports in the high mountains. Therefore, in good weather and intense sunshine always high mountain sunglasses or a corresponding ski goggles should be worn.
Water strongly reflects UV rays, but not only in the frozen state. The risk of snow blindness is therefore also in water sports or boat and boat trips. Even crossing smaller waters on a ferry can be risky in strong sunlight. Therefore, on these occasions, good sunglasses should be worn. In sunbeds, goggles given by the staff must be used at all costs, as the risk of eye damage from UV light is particularly high here.
If there is still a blurring of the eyes, care must be taken immediately for shade and a doctor, better still an ophthalmologist, be visited. If the person concerned does not wear safety goggles, they should borrow one on their way to the doctor in order to relieve their injured eyes as much as possible.
The eyes often respond to UV-induced corneal erosion with severe itching, as well as a foreign body sensation. However, under no circumstances should be scratched or contemplated, otherwise there is a risk that the damaged cornea may be inflamed.