(Staying safe during the eclipse)
Children should be closely supervised during the eclipse as they are one of the groups most at risk of eye damage, says a consultant ophthalmic surgeon in this weekend's BMJ. Mr Jonathan Dowler from Moorfields Eye Hospital in London also warns that those with existing eye problems and people who have been drinking alcohol or using recreational drugs are also at particular risk from looking at the sun during the eclipse. The eclipse will occur at the height of summer, as the sun nears its zenith over a densely populated area and therefore may be followed by an even greater incidence of retinal injury than reported after other recent eclipses, he says.
Solar retinopathy is caused by looking at the sun with the naked eye, causing a rise in retinal temperature of 4 C, which induces photochemical injury to the retinal receptor cells. The condition may occur rapidly, without pain and without being immediately apparent and no treatment has been shown to be effective for the condition, says the author. Furthermore, photochemical damage is cumulative and there are concerns that such injuries may predispose people to eye disease in later life, suggests Mr Dowler.
The only safe time to look at the sun, says the author, will be during the short two minute period of total eclipse and that one should look away the moment the first rays of the sun appear at the edge of the moon. Binoculars and telescopes should not be used he warns (viewing the sun this way produces a 10-25 C temperature rise in the retina which causes thermal burn of the eye). Other suggested methods of viewing such as through smoked glass, photographic film, compact discs, or wearing one pair (or even several pairs) of sun glasses will not give people adequate protection says Mr Dowler.
He also warns that the widely available ‘solar viewers' may not give sufficient protection, even if they carry the CE mark to show they have been tested to comply with European Union personal protection equipment standards. Dowler explains that this is because damage to the aluminised polyester, from which they are commonly made, may compromise their protective effect and also many have been designed in a single size to fit all, which are unlikely to fit children's faces properly.
Reiterating warnings from the Department of Health, the Royal College of Ophthalmologists and the College of Optometrists, the author suggests that the safest way to witness the eclipse is by indirect methods, such as a projection.
(Note: a total solar eclipse will occur on 11 August at 11:11 hours over south west England and north west France.)
Contact:
Edmund McMahon Turner, Press Office, Moorfields Eye Hospital, London edmund@mehpr.demon.co.uk