When the cornea curves or flattens unevenly, the result is astigmatism, which disrupts focus of near and distant vision.
散光是当角膜变弯或者变平时表面不平坦，影响视近、视远时的聚焦。
That can be addressed with multifocal lenses, which have concentric rings of material that offer alternate bands of near and distant vision.
这个问题可以使用多焦点人工晶体来解决，它拥有一些同心圆环，该圆环上的物质能提供交替调节近距离和远距离视力的区带。
Farsightedness is the opposite, in a way: A shorter-than-average eyeball or too-flat cornea focuses light behind the retina instead of on it, making near vision and sometimes distant vision blurry.
远视在某种程度上则相反，是较正常短些的眼球前后径或者太平坦的角膜使光线聚焦于视网膜后而不是之上，这导致近景视觉模糊和有时的远景视觉模糊;
This is because the distance from the eyes to the keyboard or music stand is intermediate between reading and distant vision.
因为在弹奏时眼睛与键盘或乐谱的距离正好在平时阅读视距和眺望远处的物体之间。
This is because the distance from the eyes to the keyboard or music stand is intermediate between reading and distant vision.
因为在弹奏时眼睛与键盘或乐谱的距离正好在平时阅读视距和眺望远处的物体之间。
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