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原帖由 大龙卷风 于 2009-5-21 16:34 发表 
可能是: 只管近视不管散光不管远视 or ver visa
Single vision lens 要么近视，要么远视
Multifocal lenses 近视远视都有
The most commonly prescribed spectacle lenses are 'single vision' lenses. Single vision lenses have only one power in the lens and allow you to see clearly in either the distance or at near. Most younger people who wear spectacles have single vision lenses but as people get older, they gradually lose the ability to alter the focus of their eyes ('presbyopia'), and usually some time between the ages of 40 and 50, they develop a need for corrective lenses for both distance and near vision. They can use two pairs of single vision spectacles and change them as necessary or, alternatively, one pair of multifocal lenses. As the name suggests multifocal lenses are lenses which have more than one power, allowing the wearer to focus at more than one distance. |
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发表于 2009-5-21 16:59
