This feedback system is used by the eye in an effort to attain an ideal eye length, neither farsighted nor nearsighted. This state is called emmetropia.

眼睛尽力用这个反馈系统，达到理想的视力长度，不是远视也不是近视，这个状态就称正常视力。

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This feedback system is used by the eye in an effort to attain an ideal eye length, neither farsighted nor nearsighted. This state is called emmetropia.

眼睛尽力用这个反馈系统，达到理想的视力长度，不是远视也不是近视，这个状态就称正常视力。

youdao