By Jane Goulden 

Glasses for children  which provide some form of filtering to protect eyes from sunlight will not be safe enough to enable the partial eclipse of the sun on January 4 to be viewed directly. The Government's Chief Medical Officer, Dame Sally Davies has warned: "Under no circumstances should people look directly at the sun during a partial eclipse. The risks of doing so are very real and could lead to irreversible damage to eyesight and even blindness. Children are particularly vulnerable as they may be tempted to take a peek. We would urge parents to explain the danger to their children."

People should not look directly at the sun during a partial eclipse on Tuesday since this can lead to permanent damage to eyesight or even blindness. Glasses for children  with standard sun filters may make them feel they can view the eclipse directly so parents are warned to be especially vigilant. In October 2005 when a partial eclipse occurred, a young boy lost his central vision by staring directly at the sun in his school playground. The Department of Health advises that viewing the sun during a partial eclipse requires special protection or indirect viewing methods. Only properly designed and certified solar filters should be used for direct viewing of the sun's disk.

The Department has emphasised that observing the eclipse through a telescope, binoculars, glasses for children  and adults with standard sun filters, photographic film or camera is not safe and recommends that it is best viewed via the television or live webcasts. The partial eclipse of 4 January will be visible in much of the UK between 0800 and 0930 GMT. The moon will pass across the front of the sun but not cover it completely, creating a partial eclipse. The amount of sun obscured in the middle of the eclipse varies from around 75% in London to barely 40% in Glasgow.

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