鄭大夫弱視問答：雙眼優於單眼？
Question: Do we see the same with one eye as we do with two?
問題：雙眼和單眼看到的是一樣的嗎？
Answer: Absolutely not!
答案：肯定不一樣！
If this were so, God or nature, in all powerful wisdom, would have given us just one eye instead of two. It would certainly make eyeglasses cheaper, and it would take a lot less time to put on make-up in the morning.
Advertisements
如果是這樣的話，那麼我們生來，就應該只有一隻眼睛，而不是兩隻眼睛。這樣配眼鏡更便宜，早上化妝還能省出很多時間。
圖1 如果人只有一隻眼睛
Can we live with just one lung or kidney? Sure, but in spite of the fact that we can survive with just one, we also know that we are not at our full potential, and the body operates much better and more efficiently when we have two of each.
Advertisements
人可以只有一個肺或者一個腎嗎?當然可以，只有一個器官時，我們仍能存活，但這樣就不能充分發揮身體的潛能，當我們有兩個肺兩個腎時，我們的身體能更好的運作。
圖2 眼睛長在兩側
Having two eyes positioned on the front of the head is what allows us to have binocular vision and stereopsis (3D). This has an advantage for hunting, and thus for survival.
兩隻眼睛長在前面，這讓我們擁有了雙眼視覺和立體視覺(3D)。
這樣打獵更有優勢，更有利於生存。
The same is true for our eyes. Can we live with one eye? Certainly the answer is also yes, but there are many important benefits from having two eyes. One of the most important is stereopsis or the ability to see in 3D. This can only occur if there are two eyes working together as a team.
我們的眼睛也是這樣。我們可以用一隻眼睛生活嗎?答案也是肯定的。但是雙眼會給我們帶來很多重要的好處。其中最重要的就是立體視覺，或者說是觀看3D圖像的能力。只有在雙眼協調工作的時候，才能產生立體視覺。
圖3 眼睛長在前面
Man, along with apes, chimpanzees, lions, and eagles have two eyes located in the front of the head. Indeed, all large predators have their eyes facing forward as compared to other animals, such as many reptiles and amphibians, which have their eyes on the side of their head.
不僅是人類，猿猴、黑猩猩、獅子和老鷹，雙眼都長在頭部前面。事實上，所有的大型食肉動物，眼睛都長在前方，而其他動物，比如許多爬行動物、兩棲動物，它們的眼睛長在頭部的兩側。
Having binocular vision and stereopsis(3D) is much more than just having better depth perception. A 2013 study in Optometry& Vision Science by Ponsonby, Smith, and colleagues discussed various factors associated with poor stereopsis including prematurity, convergence insufficiency, amblyopia, strabismus, migraine, attention deficit disorder and poor literacy.
具有雙眼視覺和立體視覺(3D)，不僅僅是具有很好的深度知覺(人對物體遠近距離的感知即深度知覺)。2013年，Ponsonby, Smith等在《視光學與視覺科學》中發表的研究，討論了與立體視覺受損的相關因素，包括早產、集合不足、弱視、斜視、偏頭痛、注意力缺乏症和讀寫能力低下。
圖4人類的雙眼長在前面
The many advantages of good binocularity will be discussed in depth in next chapter .
在下一期，我們將深入探討，具有良好雙眼視覺的優勢。