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Why can people see more clearly when they squint their eyes?
Answer 1:

What a fantastic question! The short answer is: squinting changes the shape of our eye.

The long answer is: the eye is a very complicated organ. Light enters the eye through the pupil and travels to the lens. The lens uses muscles in the eye to change shape in order to focus the light on a sensory area at the back of the eye known as the retina. The retina contains both rod cells (vision in low light) and cone cells (color vision). A very small spot in the middle of the retina, known as the fovea, is made up of only cones and is responsible for our ability to see fine details clearly. Once light reaches the retina, it encounters a chemical called rhodopsin which converts the light into an electrical impulse that our brain can process as vision. For more details check out this website


human- eye

When we age the lens of our eye can become stiff and lose its ability to focus light properly. People also have slightly different shapes of eyes. If the eye is not perfectly round, which often has a genetic component or can be caused by physical damage to the eye, then the light coming in through the lens will be focuses slightly off center causing blurry vision. Believe it or not, when we squint we are actually changing the shape of our eyes ever so slightly, and by doing so the light is focused correctly back onto the fovea. Light traveling into our eye comes from many different angles and must all be focused together onto a single area at the back of the eye. When we squint there is also less light entering our eyes, and the light that is entering is only comes from a limited number of directions since our eyelids are covering up the rest. Now only a few beams of light need to be redirected in order to see clearly.

So basically, squinting allows us to see better in two ways: by changing the shape of our eye and letting in a limited amount of light that is more easily focused.

Could you imagine having to squint all the time in order to see clearly? Try squinting and holding it for a few seconds. Now imagine the strain on your eyes if you had to do that all the time in order to see anything clearly! Glasses and contact lenses work by substituting the eyes lens, which is focusing light incorrectly and causing blurry vision, so that people don't have to squint all the time. Each person needing vision correction requires a unique type and power of lens in order to adjust the focal point of incoming light on their retina and see clearly. These complex concepts have been used by scientists and doctors in an attempt to permanently cure people with blurry vision. You have probably heard of LASIK eye surgery, which is a procedure done to actually change the shape of the front of someone's eye in order for it to more accurately focus incoming light. Unfortunately there is no exact formula for changing the shape of someones eye to achieve perfect vision and there are some serious risks involved with the procedure. For more information on LASIK, check out this website


LASIK



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This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships