In a front-on view of the back of the eye, the optic nerve head looks like a white disk. This region is filled by the optic nerve head. Looking at the diagram above, you can see that this leaves a large ‘gap’ between the cells making up each layer. Why? We have no idea – it’s a weird trait we’ve evolved to have! And yes, this means light needs to travel through the rest of the retina to reach the photoreceptors! Author’s ownĪ consequence of this structure is that the axons of the ganglion cells now need to travel through the retina to reach the back of the eye, and eventually, the brain. Well surprisingly, human retinas don’t look like that! Our photoreceptors are closer to the back of the eye, and our ganglion cells are closer to the front of the eye. Knowing that, it’s natural to assume the arrangement of the eye to look like this: Author’s own Source: National Eye Institute via Flickr. The retina can be found at the back of the eye. Ganglion cells – These are the cells linking the eye to the brain! Most of the length of these cells, called axons, form the optic nerve leading out of the eye connecting to the brain.Ī cross-section of the eye facing right.Bipolar cells – Think of these as intermediate cells, just passing along the information.Photoreceptors – These cells are the ones that react in the presence of light, starting the whole process!.Simplified, the information given by light travels through 3 layers of cells in this order: The retina converts the light information entering from the front of your eye into information your brain can process. The blind spot I’m referring to is actually the result of the structure of the retina, tissue found at the back of your eye. It’s normal!īlind spot? Uh… do I need to do a head-check or something? Nothing, really! Everything that just happened was in fact a result of your visual system and something it contains called a blind spot. What on earth just happened to my finger? Ta da! With any luck, your right index finger should have disappeared without a trace! Ignore the weird stares from the people around you and give yourself a pat on the back.
What’s happened to your right index? Source: Author’s own. The ‘X’ represents where you should be looking. With your arms fully stretched forward, here’s what your hands should look like. Without moving your gaze from the top of your left index finger, observe your right index finger.
Fully stretch out your left arm in front of you, palm facing away.Now before you frantically look around for a knife-wielding finger collector, don’t worry – it’s perfectly safe! I’ll even reattach your finger for free! All you have to do is the following… Hey you! Yes, the one reading this blog! I’ve got a magic trick for you…I’ll make one of your fingers disappear, quickly and painlessly!
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