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A 66-year-old male presents with the sudden onset of excruciating, bilateral eye pain described as “coal burning in my eyes.” Visual acuity is 20/60 OU. Twelve hours prior he had been repairing a defective 50W ultraviolet (UV) light box. The top and bottom rows are slit lamp and fluorescein images of the right and left corneas, respectively.

1.	The above condition was most likely produced by which of the following:
	c -- UV radiation damage to corneal epithelial cells UV keratitis or photokeratitis occurs when UV radiation (usually UVB 290-310nm) is absorbed by the corneal epithelial cells and causes epithelial cell loss and burn. Symptoms typically start 6-12 hours after exposure. The patient may not be aware of the initial insult at first but later may experience severe bilateral eye pain, injection, and photophobia. The slit lamp images show damaged corneal epithelial cells which appear gray and stain with fluorescein.
2.	In this case, the fluorescein staining represents which of the following?
	e -- (b) and (d) Fluorescein shows punctate staining of the corneal epithelium (PEE) in the interpalpebral fissure by binding to the damaged epithelial cells. Mucus in the tear film usually stains larger and is not as confluent as PEE. Filaments are mucous attached to damaged corneal epithelial cells (arrows). Using electron microscopy, “peculiar substance” is seen within the corneal epithelium in Meesmann’s corneal dystrophy and does not stain with fluorescein.
3.	Although this condition is rarely seen today, which populations are at an increased risk?
	e -- all of the above UV keratitis can be seen in populations living in snow or desert-rich areas and is common among certain occupations.  Welder’s are at increased risk. Other potential exposures include solar tanning, sunlamps, germicidal UV lamps, damaged metal halide lamps, and aquaria disinfection lamps. UV keratitis should always be suspected in an individual with acute onset bilateral eye pain who has been exposed to high energy light.
4.	Which of the following is true regarding treatment and prognosis?
	f -- (c) and (d) UV keratitis is preventable. The American National Standard Institute for non-Rx sunglasses recommends that the sunglasses block most UVA and UVB light and should provide a good fit.  Individuals at risk from occupational exposure should wear eye protection at all times.  UV keratitis is self-limiting and typically responds well to aggressive lubrication.  A cycloplegic medication may have a role in those with severe photophobia and an analgesic may be used for pain.  Symptoms typically resolve in 24-72 hours as the corneal epithelium regenerates.  Most cases do not require antibiotic therapy.  Chronic UV exposure may result in pterygium formation, cataract formation, melanoma, and climatic droplet keratopathy.