I recently talked to a nice lady who had multiple experiences seeing angels. She said you can catch them with the corner of your eye. They look like flickers of vibrating energy, bringing comfort and unconditional love in moments of sadness. She sounded so touching that I didn't have the heart to tell it was the peripheral vision playing tricks on her mind.
Fig 1 We can't make sense of the text read from the corner of the eye.
Our eyes have a certain structure to help us manage everyday tasks in the best way possible. We have a central vision that gives us a clear picture of the object in front of us and a peripheral vision that gives us a general idea of the surroundings. For example, when we drive, we keep our eyes on the road while still catching a side view for possible hazards. If peripheral vision alerts us to some disturbances on the side of the road, we turn our heads to focus on them and investigate in detail what happens there.
So, how does the eye anatomy support central and peripheral vision? Our vision relies on light to tell us about the outside world. Light enters the eye through the pupil and excites photoreceptor cells in the retina at the back of our eyeball (Fig 2). The optic nerve passes the excitations to the brain, which converts them into visual images.
Fig 2 The structure of the human eye.
The central part of the retina, known as the macula, is responsible for central vision. It has the highest concentration of photoreceptors, which explains why the information collected from the central part of the retina is most detailed. The center of the macula is most densely packed with the photoreceptors; this is the area we use to discern the finest details. If you connect the macular and pupil centers, you find the line along which our vision is the sharpest. When we read, for example, we constantly roll our eyes over the text because we keep aligning the letters with the macular center. Outside the central retina, the density of the photoreceptors starts falling substantially, with the lowest at the edges of the retina. That's why peripheral vision produces poor detail perception, being the worst at the visual field boundaries.
Fig 3 We can't see the number plate and sunset in detail simultaneously, only one object at a time.
Consider this scenario. You drive on the country road, admiring a sunset over the lake (Fig 3). Your peripheral vision catches an oncoming car looking like one of your friends. Can you see the registration number without shifting your gaze from the sunset to the car? You can't. Now, focus your eyes on the number plate. Can you see the sunset details? No, you lost them. Move your eyes slightly away from the number plate. You can still see what's on it clearly, but your brain struggles to connect letters and digits into a meaningful sequence and recognize it as a unit of information. You'll find memorizing the number plate from this angle difficult. This is because you're crossing the central vision boundary, and the data collected from the peripheral retina goes to a different part of the brain with lower processing power. You can repeat this exercise with the text (Fig 1). Moving it away from the central position, you will first lose the ability to understand the meaning of the words and then find the words increasingly blurred.
We can't focus on two objects simultaneously, only one at a time. This may seem like a disadvantage, but it's a blessing. Imagine you are at a party with many people in the room. Could you concentrate on your conversation with a friend in front of you if you could hear all the other people in the room just as well? Nature is wise. It always finds a winning balance, bringing the best of both worlds. The central vision helps us to focus on the object of main interest, while the peripheral vision keeps us updated on the changes in the background. If something there requires our attention, we turn our heads and investigate it in clear view.
Angels live in the corner of our eyes for the same reason monsters hide in the darkness. They like places with poor visibility where imagination can run wild. The nice lady may not realize it, but she would turn her head whenever she thought she caught some presence with her side vision. Our brain treats changes in the background as potential danger signals, stimulating involuntary reflex responses. So, if an angel or a monster disappears when you look directly at it, then it wasn't there to begin with.
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