Photokeratitis

Photokeratitis is an eye condition, but to understand this condition, we must first know what a cornea is. The cornea is found in the outer layer of the eye and serves as the window of the eye.

It helps the eye focus on entering light rays. The cornea is transparent and made largely of connective tissue with a thin surface layer of epithelium. There are few cells and no blood vessel in the cornea, and cells plus collagenous fibers form unusually regular patterns.

Photokeratitis is a rare painful eye disorder that occurs when the eye is exposed to invisible rays of light known as ultraviolet (UV) rays, these rays, especially the UVA and UVB rays cause an inflammatory condition that affects the cornea of the eye.

The rays can either be from the sun, snow-reflection or man-made sources such as a sun lamp, welders’ arc, photographer’s flood lamps, and halogen desk lamp.

Photokeratitis can also be referred to as having a sunburned eye when caused by UV rays but when from other etiologies, it is referred to as keratitis which is caused by an infection to the eye.

Infectious keratistis is a more common condition; individuals who use contact lenses may experience keratitis more frequently than people who do not use contacts.

Non-infectious keratitis (photokeratitis) is more of an occupational or environmental consequential condition, affecting the cornea- which covers the colored parts of the eye, and also the conjunctiva- the clear tissue covering the white part of the eye and inside the eyelids.

Photokeratitis has a form known as snow blindness. This form of photokeratitis is associated with UV rays that reflect off ice and snow. Cornea damage from UV rays is very common in the North and South pole regions and also in the high mountains where the air is thinner and provides a thinner protection from UV rays from the sun.

The term Photokeratitis or snow blindness is also employed when freezing of the cornea’s surface occurs, as well as severe drying of the corneal surface due to extremely dry air.

High altitude activities such as skiing, mountain climbing and snowmobiling are usually associated with snow blindness.

Causes of Photokeratitis

In this article, we are going to be classifying photokeratitis into two classes, based on the origin of the causes. Photokeratitis will be classified into infectious keratitis and non-infectious keratitis.

The primary objective of this article is to educate on the conditions that can primarily affect the cornea and to do this, it will be necessary to associate infectious keratitis with photokeratitis so as to get a wider understanding of conditions affecting the cornea.

Infectious Keratitis

An infectious keratitis condition can be caused by any of the following:

  • Bacteria such as Pseudomonasaeruginosa and Staphylococcus aureu commonly cause bacterial keratitis. Mostly develops from improper use of contacts.
  • Fungi keratitis is frequently caused by Candida, Aspergillus, or Fusarium activities. It also arises mostly from using contact lenses improperly. However, a person can be exposed to these fungi outdoors.
  • Viral keratitis is primarily caused by the herpes simplex virus, progressing from conjunctivitis to keratitis
  • Parasitic infection such as Acanthameoba keratitis has become common in those using contact lenses in the United States. The parasite can be picked up during swimming, walking in wooded area, or getting infected water into lenses.   

Non-infectious photokeratitis

Non-infectious photokeratitis can be caused by ultraviolet rays. UV-A and UV-B rays from the sun can particularly cause short and long-term damages to the eyes and inhibits a person’s vision.

Although, UV-C rays also emit from the sun these rays are mostly absorbed by the ozone layer so they do not get to the eyes.

Apart from sunlight, other sources of ultraviolet light that causes photokeratitis are:

  • Lamps used in tanning booths or bed
  • Laser light
  • Mercury vapor lamps and halogen desk lamps
  • Arc welding equipment
  • Photographic floor lamp
  • Sun rays reflection from snow, ice, sand, and water

NB: The cornea refracts lights within the eye and directs light into the retina. When excessively exposed to these harmful UV rays, either from the sun or other made-made sources, the rays causes the cornea to burn, like a sunburn to the skin.

Other factors apart from ultraviolet rays and infection can also result in keratitis, they include:

  • Use of contact while swimming
  • Eye trauma
  • Weakened immune system
  • Extended use of contacts 

Symptoms of Photokeratitis

Like sunburn to the skin, a person might not notice a photokeratitis until well after the damage has occurred.

A person who has photokeratitis may experience some of the following symptoms:

  • Pain in the eyes
  • Redness
  • Watery eyes
  • Swelling
  • Light sensitivity
  • Eyelids twitching
  • Gritty sensation in the eyes
  • Temporary loss of vision
  • Seeing halos
  • Headaches
  • Rarely; color changes in vision

Symptoms may last for at most 24 hours but usually, disappear within 48 hours. The longer the exposure to UV light, the more severe the symptoms might be.

Diagnosis of Photokeratitis

Primary health care givers usually diagnose photokeratitis by investigating a patient’s recent activities, conducting a physical examination of the eyes, and using an eye drop dyed with fluorescein to observe for UV damages.

NB: Flourescein is a harmless organic compound and dye. It is widelt used as a fluorescent tracer for many medical and forensic applications.

Treatment of Photokeratitis

Snow blindness and photokeratitis effects are short-term and normally fade away on their own, so treatment is focused on making a patient feel better as the eyes heal. If a person uses contact lenses, he/she must remove them immediately.

Get out of the sun and enter into a dark room. For pain an symptom relieves, doctors may recommend:

  • Placing cold press over the eyes
  • Using artificial tears
  • Pain relief may be recommended by an ophthalmologist
  • Use of eye drop antibiotics
  • Avoid scratching or rubbing the eyes as they heal. Symptoms normally fade in a day or two.

Prevention of Photokeratitis

The best ways to prevent photokeratitis is to protect the eyes from UV light radiation. Skilled ophthalmology specialists at USC Roski Eye Institute strongly suggest that individuals of all ages take necessary precautions to protect their eyes, including:

  • Do not use sunlamps, tanning beds and booths
  • Always wear UV-A and UV-B rays blocking sunglasses
  • Wear UV-blocking goggles during surfing, snowboarding, swimming, and welding activities.
  • Avoid prolong exposure to direct sunlight, especially between 10am and 4pm.
  • See an eye specialist at least once a year for a complete eye examination.

Summary

Good news! The cornea of the eye repairs itself rapidly and usually heals within 2 days if further damages are prevented. However, some complications might arise during the course of photokeratitis such as infection.

As such it is very important to recheck with an eye doctor when it is scheduled. UV exposure adds up with time and long term exposure to even little amounts of UV radiations can increase the risk of developing a cataract or macular degeneration especially in people with a weakened immune system.

Long-term exposures can also cause tissue elevations on the surface of the eye; these are referred to as pterygia and pingueculae, use of sunglasses faithfully when outdoors may limit the occurrence of these conditions.

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