The curvature of the Earth wouldn’t start to cut things off from your view quite so soon. However, if your vantage point were much higher off the ground, then the horizon line could be a lot farther away. If you were lying down on the beach with your head less than a foot off the ground, your eyes would be able to see about a mile out over the water. To put it another way, if you’re standing on a beach in Florida or driving past the farms of Nebraska (both places where it’s relatively flat), the farthest part of the horizon that you can see is about 3 miles away. As a result, on a flat surface with your eyes 5 feet or so off the ground, the farthest edge that you can see is about 3 miles away. The Earth curves about 8 inches per mile. But, a sightline is really any uninterrupted visual angle from a person’s eyes to what the person is trying to see.Īside from obvious visual obstructions like trees, buildings, and clouds, there’s one major factor that can reduce your sightline: the curvature of the Earth. People often use the term “sightline” in a theater to describe the line of sight from an audience member’s seat to the stage. the size of the object that you’re viewing.The rods and cones convert the light rays into electrical impulses, and these travel from the eye through the optic nerve to the brain, which converts them into images.Īssuming that all of the body parts and processes that are necessary for clear vision are working normally, then the limitations on how far you can see come down to:.Light rays then pass through the lens, which sharpens them as they reach the retina, the thin tissue layer at the back of the eye that contains tiny nerve cells known as rods and cones.At the same time, the muscles in the iris - the colored area around the pupil - control the size of the pupil, making it smaller in bright light and larger in a darker setting.The cornea bends the light rays to allow them to enter the pupil, or the dark center of the eye. ![]() Light reflects off an object and passes through the cornea, which is the transparent outer layer of the eye.When you look at anything, a rapid and complex sequence of actions will take place in the eye and brain: If you have 20/100 vision, you would still be able to see an object clearly from 20 feet away, but someone with normal vision would see it clearly from 100 feet.Ĭonversely, if you have 20/12 vision, you can see something clearly at 20 feet that most people need to be 12 feet from to see clearly. That simply means that you can clearly see something 20 feet away that you should be able to see from that distance. The phrase “visual acuity” refers to the clarity of your vision.Įxperts consider normal, or healthy, visual acuity to be 20/20 vision.
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