Photokeratitis: Difference between revisions

The injury may be prevented by wearing eye protection that blocks most of the ultraviolet radiation, such as [[Welding helmet#Goggles|welding goggles]] with the proper filters, a welder's helmet, sunglasses rated for sufficient UV protection, or appropriate snow goggles. The condition is usually managed by removal from the source of ultraviolet radiation, covering the corneas, and administration of pain relief. Photokeratitis is known by a number of different terms including: '''snow blindness''', '''arc eye''', '''welder's flash''', '''sand eyes''', '''bake eyes''', '''corneal flash burns''', '''flash burns''', '''niphablepsia''', or '''keratoconjunctivitis photoelectrica'''.

Common symptoms include pain, intense [[lacrimation|tears]], [[Blepharospasm|eyelid twitching]], [[Photophobia|discomfort]] from bright light,<ref>{{cite web|url=http://www.gpnotebook.co.uk/cache/389349390.htm |title=Arc eye – General Practice Notebook |date=2007-03-25 |access-date=2012-02-07 |archive-url=https://web.archive.org/web/20070325003031/http://www.gpnotebook.co.uk/cache/389349390.htm |archive-date=2007-03-25}}</ref> and [[Miosis|constricted pupils]].

Any intense exposure to UV light can lead to photokeratitis.<ref>{{Cite web|url=https://www.aao.org/eye-health/diseases/photokeratitis-snow-blindness|title=What is Photokeratitis — Including Snow Blindness?|last=Porter|first=Daniel|date=February 16, 2019|website=American Academy of Ophthalmology|access-date=November 22, 2019}}</ref> In 2010, the Department of Optometry at the [[Dublin Institute of Technology]] published that the threshold for photokeratitis is 0.12 J/m².<ref>{{Cite web|url=https://www.avehjournal.org/index.php/aveh/article/download/137/106 | title=Review of Photokeratitis: Corneal response to ultraviolet radiation (UVR) exposure*| publisher= The South African Optometrist | access-date=1 November 2021}}</ref> (Prior to this, in 1975, the Division of Biological Effects at the [[FDA Center for Devices and Radiological Health|US Bureau of Radiological Health]] had published that the human threshold for photokeratitis is 50 J/m².<ref>{{Cite web|url=https://books.google.com/books?id=lzhcL6PiXgIC&pg=PA4 | title=A Review of Biological Effects and Potential Risks Associated with Ultraviolet Radiation as used in Dentistry | year=1975 | publisher= FDA, The US Bureau of Radiological Health | access-date=1 November 2021}}</ref>) Common causes include [[Welding|weld]]ing with failure to use adequate eye protection such as an appropriate [[welding helmet]] or welding goggles. This is termed ''arc eye'', while photokeratitis caused by exposure to [[sunlight]] reflected from ice and snow, particularly at elevation, is commonly called ''snow blindness''.<ref name="eMedicine" /> It can also occur due to using [[Indoor tanning|tanning beds]] without proper eyewear. Natural sources include bright [[sunlight]] [[Reflection (physics)|reflected]] from snow or ice or, less commonly, from sea or sand.<ref name="gpn">{{cite web|url=http://www.gpnotebook.co.uk/simplepage.cfm?ID=-268042203|title=Snow blindness|publisher=General Practice Notebook|access-date=November 19, 2008}}</ref> Fresh snow reflects about 80% of the UV radiation compared to a dry, sandy beach (15%) or [[sea foam]] (25%). This is especially a problem in [[Polar regions of Earth|polar regions]] and at high altitudes,<ref name="eMedicine">{{cite web|url=http://www.emedicine.com/emerg/topic759.htm|title=Ultraviolet Keratitis|last=Brozen |first=Reed |author2=Christian Fromm |date=February 4, 2008|publisher=eMedicine|access-date=November 19, 2008}}</ref> as with about every {{cvt|300|m|ft|sigfig=1}} of elevation ([[Height above mean sea level|above sea level]]), the intensity of [[UVultraviolet]] rays]] increases by four percent.<ref name="berkeley">{{cite web|url=http://www.uhs.berkeley.edu/home/healthtopics/sunsafety.shtml|title=Sun Safety|date=April 2005|publisher=University of California, Berkeley|access-date=November 19, 2008}}</ref>

The [[Inuit]], [[Yupik peoples|Yupik]], and other [[Arcticcircumpolar peoples]] have carved [[snow goggles]] from materials such as [[driftwood]] or [[caribouantler]]s of [[antlerReindeer|caribou]]s to help prevent snow blindness for millennia.<ref name="YupikGoggles">{{cite web |url=https://mymodernmet.com/inuit-yupik-snow-goggles/ |title=Indigenous People in Alaska Invented Snow Goggles Centuries Ago To Protect Eyes and Improve Vision |author=Jessica Stewart |date=2021-12-17}}</ref> Curved to fit the user's face with a large groove cut in the back to allow for the nose, the goggles allow in a small amount of light through a long thin slit cut along their length. The goggles are held to the head by a cord made of caribou [[Tendon|sinew]].<ref name="Norn1996">{{cite book|url=https://books.google.com/books?id=WWVb9tZqq4MC&pg=PA3|title=Eskimo Snow Goggles in Danish and Greenlandic Museums, Their Protective and Optical Properties|author=Mogens Norn|publisher=Museum Tusculanum Press|year=1996|isbn=978-87-635-1233-6|pages=3–}}</ref>

Explorers of the polar regions employed various methods and materials to protect their eyes from the harsh glare in snowy environments. [[Edward Evans, 1st Baron Mountevans|Edward Evans]] noted the popularity of yellow and orange-tinted glasses among explorers, though some showed a preference for green. Despite the availability of blue and purple glasses, [[Edward L. Atkinson|Atkinson]] advised that all glasses, regardless of colour, should undergo spectroscope testing to ensure effectiveness.

The pain may be temporarily alleviated with anaesthetic [[eye drop]]s for the examination; however, they are not used for continued treatment,<ref>{{Cite web|url=https://www.college-optometrists.org/guidance/clinical-management-guidelines/photokeratitis-.html|title=Photokeratitis (Ultraviolet [UV] burn, Arc eye, Snow Blindness)|date=April 4, 2018|website=The College of Optometrists|access-date=November 22, 2019}}</ref> as anaesthesia of the eye interferes with corneal healing, and may lead to [[corneal ulcer]]ation and even loss of the eye.<ref>{{Cite journal|last=Khakshoor|first=Hamid|date=October 2012|title=Anesthetic keratopathy presenting as bilateral Mooren-like ulcers|journal=Clinical Ophthalmology|volume=6|pages=1719–1722|pmc=3484722|pmid=23118524|doi=10.2147/OPTH.S36611 |doi-access=free }}</ref> In the 1900's polar explorers have treated snow blindness by dripping cocaine into the eye.<ref>{{Cite web |date=2012-09-26 |title=Shackleton’s Medical Kit |url=https://granta.com/shackletons-medical-kit/ |access-date=2024-07-12 |website=Granta |language=en-US}}</ref> Cool, wet [[compressDressing (medicalmedicine)|compresscompresses]]es over the eyes and [[artificial tears]] may help local symptoms when the feeling returns. [[Nonsteroidal anti-inflammatory drug]] ([[NSAID]]) eyedrops are widely used to lessen inflammation and eye pain, but have not been proven in rigorous trials. Systemic (oral) pain medication is given if discomfort is severe. Healing is usually rapid (24–72 hours) if the injury source is removed. Further injury should be avoided by isolation in a dark room, removing contact lenses, not rubbing the eyes, and wearing sunglasses until the symptoms improve.<ref name="eMedicine" />

* [[Health effects of sunsunlight exposure]]

* [[Over-illuminationLight pollution]]