AP Biology class blog for discussing current research in Biology

Put it all in focus

We’ve all had that moment where we squeeze our eyelids into tiny slits in hoping the blurry paper or board in front of us will clear up and wonder, Why am I making my eyes smaller to see better? That doesn’t seem to make sense! The key is to start thinking of your eyes like a camera, a camera with aperture. When we look at something, photons are passing through our corneas and blending light rays together, which then pass through the crystalline lens and vitreous on their way to the retina. The physical building blocks of the eye, rods and cones, turn photons into electromagnetic impulses that are sent to the brain to be interpreted.

So to get to the point, why do we squint? The truth is our lenses try to focus to the best of their ability but they are not entirely flexible. So blurriness is usually indicative of a lens malfunction, missing the target in the back of the retina. When you focus your eyes on something, there are massive amounts of competing light sources and surrounding stimuli in your peripheral vision which can cloud your eyes focus. Heres where the camera reference comes in: squinting your eyes is comparable to tightening the aperture of a camera, allowing less conflicting light to interfere with the image its focusing on. So in fact, squinting your eyes does not work because it is changing the shape of your lenses, but rather because it is allowing less competing stimuli to interfere with its true focus.
If vision is continually blurry, it may not be a simple malfunctioning of your lens but rather due to physical eye damage, in which case glasses might be a good investment. Maybe we should start to think of the aperture of our personal lives a little more as well, theoretically squinting to focus on important tasks and present moments rather than being distracted by the ever-present stimuli around us. Just a thought…
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1 Comment

  1. Nicheloss

    Nice article! When I read more on the crystalline lens, I found a condition called Presbyopia, where the eye’s focussing system loses flexibility. The article says that over time everybody becomes “presbyopic”. This is interesting because while it is something that increases with age, some people’s crystalline lens stiffen earlier. Generally, a pair of specialized reading glasses provides relief to those affected.

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