The most common of these are eyestrain, double vision, temporary short-sightedness and visual fatigue.

BBC: Computer eye tests

United goalkeeper Edwin van der Sar suffered double vision as a result of the tear gas fired into the stand.

BBC: SPORT | Football | Europe | Uefa launches Man Utd crush probe

One, inevitably, is the double vision: two sets of eyes, often from two identical faces, staring out at the world together.

ECONOMIST: Double vision

She confessed to Rich that, for the past two months, she had experienced double vision and was unable to feel her hands.

NEWYORKER: Letting Go

The beautiful breasts, however, were only one reason for the double vision.

ECONOMIST: Jane Russell

Luetscher still has some slight swelling in his upper and lower lids, and minor double vision in the eye that the shears penetrated.

CNN: Man's eye saved after impalement

The country now has double vision.

BBC: America's fiscal suicide pact

What makes the picture work is its unflagging devotion to the play of gleam and shadow: to a vision of Hong Kong as a natural hotbed of treason and double cross.

NEWYORKER: Infernal Affairs