ULTRAVIOLET RADIATION AND THE EYE - Environmental UV Radiation: Impact on Ecosystems and Human Health and Predictive Models - page 255

Coroneo terms this effect, which can also produce a concentration of UVR at the
nasal side of the limbus and lens, "ophthalmoheliosis". He notes the more frequent onset
of cataract in the nasal quadrant of the lens and the formation of pterygium (described
below) in the nasal region of the cornea. 30
8. Pterygium and droplet keratopathies
The possible role of UVR in the etiology of a number of age-related ocular
diseases has been the subject of many medical and scientific papers. However, there is
still a debate as to validity of these arguments. Although photokeratitis is
unquestionably caused by UVR reflection from the snow, 5,31-32 pterygium and droplet
keratopathies are less clearly related to UVR exposure. 9 Pterygium, a fatty growth
originating in the conjunctiva that produces visual loss as it progresses over the cornea,
is most common in ocean island residents (where both UVR and wind exposure is
prevalent). UVR is a likely etiologic factor, 4,6,9,30 and the Coroneo Effect may also play
a role. 30
9. Erythema
Ultraviolet erythema ("sunburn" or reddening of the skin - 200 nm to 400 nm)
applies to the lids of the eye. This effect appears several hours after an acute exposure
and generally lasts from 8 hours to 72 hours depending upon degree exposure and
spectral region. Thresholds are higher than those for producing
photokeratoconjunctivitis. 1,4,33 The ACGIH and ICNIRP occupational exposure limits
for UVR also protects against erythema with an added safety factor for all skin types.
10. Ocular cancers
Cancers arising from chronic exposure to UVR, particularly from UV-B (280-
315 nm), have been demonstrated for the skin; 4,34,37 however little is known about the
potential contribution of UVR to ocular cancers and ocular melanoma. It is interesting
that whilst corneal cancers do occur in cattle, they are almost unknown in humans. 16
Current theory holds that uveal melanomas are not related to UVR exposure. In any
case, there is no evidence that suggest that single, acute exposures can produce skin or
ocular tumors; chronic, repeated exposures are always required.
11. Retinal effects
Theories which suggest that UVR (and even light) may contribute to some
age-related retinal diseases are very much in debate. 1,4,9,16,30 Acute exposure to light can
produce a photochemical injury to the retina. This effect is principally from visible
400 nm to 550 nm blue light with generally only a small UV contribution in the phakic
eye. This often is referred to as "blue light" photoretinitis, e.g., solar retinitis which may
lead to a permanent scotoma. 38-41 Prior to conclusive animal experiments two decades
ago, solar retinitis was thought to be a thermal injury mechanism. 1 Unlike thermal
retinal injury, there is no image-size dependence. The ICNIRP/ACGIH B(Ȝ) weighted