Is squinting really that effective?
Male: Thanks for coming on this fact-finding trip with me and share the driving.
Female: Glad to do it. It should be a fun trip. I imagine I will learn a lot.
M: I hope so. So i think we are getting close to our exit.So I'll keep an eye on it.For there is a sign but I can't quite make it out.
F: Donne, you're squinting to see the sign. Does that really help?
M: It really does. I can read it now when I am squinting.
F: Let's see now.Light enters the eye from many directions. The lens of the eye bends these rays so that they come together at a focal point. When the rays come together at the retina， the image is in focus. If this focal point is in front of the retina, close objects are clear–nearsightedness; if it is behind the retina, distant objects are clear– farsightedness.
M: Right.Now because they are bent more, the rays that pass near the edge of the pupil are blurred more. If you can eliminate these edge rays then you will have less blurring.
F: That must be what squinting does.
M: Exactly.Squinting uses the eyelids to block the blurred rays that enter the pupil near its edge. Squinting is not a long-term solution to poor vision, but it sometimes helps in a pinch.
M: Ah,I think we can end this field trip now.I've learned about all I can stand for one day.
女：让我们现在来看看。光线从四面八方进入到人的眼睛里，眼睛里的晶状体会使这些光线转向，好让它们聚集到同一焦点。当光线聚集到视网膜，清晰的图像就形成了。如果该聚焦点在视网膜前，进出的东西就会很清楚—— 即近视；如果在视网膜后，远处的东西就很清楚—— 即远视。