A primary role of Eye Care Professionals is to make their patients aware of avoidable risks to ocular health.1However; you can be faced with significant challenges when trying to provide comprehensive protection from UV exposure for your patients. Despite the fact that consumers receive the "UV exposure is harmful for your skin" message, many are unaware of the risks to their eyes all year round.2
Facts on UV radiation3,4,5
- CUMULATIVE EFFECTS: exposure to UV radiation may increase the chance of developing eye problems later in life
- IRREVERSIBLE: over the long-term, the sun can cause irreversible harm to all structures of the eye and surrounding tissue that are left under-protected
- CHILDREN ARE AT GREATER RISK: it is estimated that children's annual dose of UV radiation is three times that of adults
- ALL YEAR ROUND RISK: UV exposure can occur all day, every day and be up to 100 times higher when reflected off snow6
1. Sulley A, Sencer S, Ruston D & R Packe. UV - What your patients don't know. Optom Vis Sci 2012 E-abstract 1255448. 2. Here Comes the Sun. Optician 2012, 244; 6362: 9-10. 3. Sasaki H, Sakamoto Y, Schnider C et al. UV-B exposure to the eye depending on solar altitude. Eye & Contact Lens 2011;37:4 191-195. 4. Here Comes the Sun. Optician 2012, 244; 6362: 9-10. 5. Maddock J et al. Use of Sunglasses in Public Outdoor Recreation Settings in Honolulu, Hawaii. Optom Vis Sci, 2009, 86 (2): 165–166. 6. Sliney, David H. Intraocular and Crystalline Lens Protection From Ultraviolet Damage. Eye & Contact Lens July 2011; 37: 250–258.
GEOGRAPHICAL AND SEASONAL EFFECTS
Location and time of year can affect the amount of UV exposure received, making it difficult to gauge exposure levels.
Exposure – at unlikely times and in unlikely locations
- Ocular UV exposure can be a significant risk all year round1 and can be worse for the eyes in different locations and at different times to the skin.
- Ocular UV exposure is greater in non-equatorial regions due to the persistent lower angle of the sun in the sky throughout the day1
- Highest ocular exposure is not at midday, but mid-morning and later afternoon – the brow shields the eye when the sun is high in the sky2
Light clouds only block about 10% of UV2 and in winter, UV exposure can be up to 100 times higher when reflected off snow.3
Not only can UV rays pierce cloud cover, they reflect off all surfaces at different – and often surprisingly high – degrees.
1. Sasaki H, Sakamoto Y, Schnider C et al. UV-B exposure to the eye depending on solar altitude. Eye & Contact Lens 2011;37:4 191-195. 2. Here Comes the Sun. Optician 2012, 244; 6362: 9-10. 3. Sliney, David H. Intraocular and Crystalline Lens Protection From Ultraviolet Damage. Eye & Contact Lens July 2011; 37: 250–258.
It can be difficult to raise patient awareness about the importance of protecting eyes against UVR and the different protective measures available. There has been a marked increase in the incidence of skin cancer worldwide, especially in fair-skinned people since the 1970s. This increase is strongly associated with attitudes about sun exposure.1
Although consumers in Europe claim to be aware of UV and its implications, few understand the impact on the eyes and the benefits of comprehensive ocular protection from UV exposure (wrap-around sunglasses, a wide-brimmed hat and UV-blocking contact lenses). What's more, consumers associate UV exposure primarily with summer and 95% tend to use some protection when it's sunny compared to just 16% in non-sunny conditions. Few actively protecting against UV exposure, despite a surprisingly high level of interest in trying UV-blocking contact lenses.2
There exists therefore a huge opportunity to educate the 89% of consumers who are less likely to recognise the importance of protection from UV exposure for their eyes.2 Explore the opportunities and find out how to educate your patients. Young eyes are particularly vulnerable and importance should be placed on starting ocular UV protection from a young age. Proactively address the topic of contact lenses with your young patients and their parents. Kids and contacts: talking with children and parents.
1. Global Solar UV Index: a practical guide. Geneva, Switzerland: World Health Organisation; 2002. 2. Sulley A, Sencer S, Ruston D & R Packe. UV - What your patients don't know. Optom Vis Sci 2012 E-abstract 1255448
PERIPHERAL LIGHT-FOCUSSING (PLF) EFFECT
Peripheral light is difficult to block with the average pair of sunglasses and, surprisingly, it can actually be just as hazardous to eyes as direct sunlight.1–4
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Corneal optics focus and intensify rays entering from the temporal periphery onto the nasal lens and nasal limbus.
STANDARD SUNGLASSES ALONE MAY NOT BE ENOUGH
Exposure to UV from peripheral source is still possible even when wearing UV-blocking spectacle lenses.
Sunglasses plus UV-blocking contact lenses
The use of a UV-blocking contact lens provides additional protection.
Measuring PLF in the laboratory4
Researchers set out to show that secondary images form on the anterior segment of the eye as a result of peripheral light-focussing. Light-ray tracing was applied to an anatomically based human eye model with a gradient index crystalline lens. The scientists founds that significant focussing of light was directed to the nasal limbus and the crystalline lens. The concentration levels measured suggest a mechanism for lens phototoxicity.
Measuring ocular PLF in the sunlight
An anatomically correct eye model was equipped with UVA and UVB sensors at the nasal limbus and was exposed to sunlight in three outdoor environments: urban, mountain and beach. The intensity of UVA radiation at the nasal limbus was the same in all three environments with or without sunglasses, suggesting that the particular sunglasses used in the study (aviator-style) offered no protection from peripheral UVR.
1. Coroneo MT. Albedo concentration in the anterior eye: a phenomenon that locates some solar diseases. Ophthalmic Surg. 1990;21(1):60–6. 2. Coroneo MT, Müller-Stolzenberg NW, Ho A. Peripheral light focussing by the anterior eye and the ophthalmohelioses. Ophthalmic Surg. 1991;22(12):705–11. 3. Kwok LS, Kuznetsov VA, Ho A, Coroneo MT. Prevention of the adverse photic effects of peripheral light-focussing using UV-blocking contact lenses,. Invest Ophthalmol Vis Sci. 2003;44(4):1501–7. 4. Kwok LS, Daszynski DC, Kuznetsov VA, Pham T, Ho A, Coroneo MT. Peripheral light focussing as a potential mechanism for phakic dysphotopsia and lens phototoxicity. Ophthalmic Physiol Opt. 2004;24(2):119–29. 5. Coroneo MT, Di Girolamo N, Wakefield D. The pathogenesis of pterygia. Curr Opin Ophthalmol. 1999;10(4):282–8. 6. Kwok LS, Coroneo MT. A model for pterygium formation. Cornea. 1994;13(3):219–24. 7. Kwok LS, Coroneo MT. Temporal and spatial growth patterns in the normal and cataractous human lens. Exp Eye Res. 2000;71(3):317–22.