新進會員
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近視：近者能視
遠視：遠者能視
老花：遠、近都不能視。好像不是因為視網膜衰退引起... |
新進會員
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>老花：遠、近都不能視。好像不是因為視網膜衰退引起...
it is because of the 衰退 of muscles for controlling the lens in eye. |
新進會員
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近視：焦點落在視網膜 (retina) 前，看近清，遠唔清. People with heavy 近視 have higher chance of retain detachment, but genes play an important part too.
遠視：焦點落在視網膜後，看遠清，近唔清. I don"t know much about 遠視.
老花：the lens 衰退引致，看近唔清，遠清. When the lens is in relax state, things far away will appear sharp. It has nothing to do with retina. |
新進會員
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老花:看近唔清, 看遠唔清. |
新進會員
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>老花:看近唔清, 看遠唔清.
Really? My mum (she got 老花) told me she can see things clearly far far away, even better than I do with glasses. |
新進會員
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新進會員
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以止幾位同埋幾個連結好似都唔多唔少有ｄ出入─＾─”
都唔知邊個真～！ |
新進會員
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近視：看遠唔清
遠視：看近唔清
老花:看近唔清, 看遠唔清
the above is correct if and only if the degree is not large, normally less than 300 degree.
If the degree is larger, all are 看近唔清, 看遠唔清. |
新進會員
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By the ways, most camera lenses are in best image quality in the middle range of focus. |
新進會員
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我遠視５０喎，但係睇近極之清，反而係遠唔清，會唔會係５０散光影響左？ |
新進會員
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視光師同我講，相同度數的散光會比近、遠視嚴重。
而50度近、遠視其實好小，唔用測量儀器的話其實唔會察覺得到... |
新進會員
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www.health4ever.com/dis_cure/ dis/eye_dis/eye_dis_14.htm - 21k
"老視（老花眼）（Presbyopia） 老視指隨年齡增長，
晶狀體核逐漸硬化，晶狀體彈性減低及睫狀肌衰弱，而令眼的調節作用
減退。. ... "
from the above, one suffers from 老花 can only focus in a smaller range of distance due to lens losing its flexibility (i.e. 晶狀體彈性減低) or/and a weakened ciliary muscle (i.e.睫狀肌衰弱). So, s/he loses the ability to focus on subjects in both very close and very far distance.
However, the range of focusing may "shift" if the eye got the short-sightness or far-sightness at the same time.
As such, people having 老花 may not have the same range of clear sight. |
