Squeamish about anything touching your eye? If so, you may not want to read on.
Isaac Newton is know for his findings in the field of mass and gravity. But his curiosity did not stop there. One of the things he was interested in was how ‘colour’ exists in nature and, more specifically, how it is interpreted by the human eye. To try to answer this question, he stuck a sewing needle with a blunt point and inserted this into his eye socket (he didn’t pierce the actual eye!). This distortion of the eyeball resulted in him seeing blurred spots due to the pressure exerted by the squashed eyeball onto parts of the retina.
In doing this, Newton was able to ascertain how the retina functioned in respect of refracting and reflecting light rays entering the eye. This finding helped pave the way for the creation of first camera, adopting a similar optical system.