Normally, the light spreading out from a single point in your field of view gets pulled back together, into a single point again, on the back of the eye top part of the picture.
However, without a functioning lens, the light from a particular point in your field of view keeps spreading out, and is projected onto a large area in your eye. Objects near each other end up smearing over the same areas on the back of the eye, etc. Being under water is about as close to not having a cornea as you can come without surgery.
The image above, though beautiful, is not to scale. What about goggles? The shallower the incoming angle, the greater the bending and also the greater the lensing effect, which in this case serves to make things more blurry. Luckily, when we look at things we tend to turn our head toward them, and the angle of the light from straight ahead isn't changed much.
Those creatures lucky enough to be able to see both in water and air do it with a combination of mucus goggles, and corneas capable of changing shape dramatically. You given idea for me but i need basic sense EEE department. Notify me of follow-up comments by email. Notify me of new posts by email. There's a book! It's a collection of over fifty of my favorite articles, revised and updated.
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Typically, when light travels from a less dense to a more dense material, the light slows down -- in most cases, anyway. And when it slows down, it bends. We use a measure called refractive index to indicate how slowly light moves in a material. Denser materials tend to have higher refractive indices. As light passes from one material to another, how much it bends depends on the change in refractive index, and the angle the light hits at. Think of a spoon in a glass of water.
It looks bent because air and water have different refractive indices. For vision, incoming light first meets the outer part of our eyes, called the cornea. Its dense material causes the light to refract. That, and the curved shape of the cornea, causes the light to bend towards the center of the eye.
After the cornea, the light eventually reaches the lens, which is even denser, further bending the light. All of this works together to create a little focused image that lands right on the back of your eyeball. But water is quite a bit denser than air, and it actually has almost exactly the same refractive index as the human cornea. This means that when light travels through the water into your cornea, it barely bends at all.
Since everything inside the eyeball stays the same, the light will still bend a bit once it hits the lens -- but underwater the human eye loses over half of its light bending power.
All you need is a little pocket of air in front of your eyes to get that bending power back, so wearing goggles will let you clearly see underwater. Incidentally, when the light travels from the water into your goggles, it will bend a bit thanks to the change in refractive index -- but that just works like a magnifying glass, making things look a little bit closer than they actually are. So how do fish get around without goggles? You can find saline solution eye drops at any pharmacy, follow the instructions and cry the soreness away.
Apply a cold compress — Wet a cloth or rag under cold water and place it over your closed eyelids for a few minutes. This should help ease any stinging, swelling, and irritation. If the rag warms up quickly then wash it again with cold water and continue.
Use tea bags — Tea bags can help ease inflammation and reduce swelling. Soak two tea bags with cool water, and place them over your closed eyelids. Keep them there until they reach room temperature. If your eyes still feel sore then repeat. Use cucumber — Cucumbers have cooling properties that can soothe irritation and restore moisture in dry, sore skin. Take a cooled cucumber and cut off two thick slices, placing them over your closed eyelids.
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