Why and how is the eye not adapted to see under water?

Question

in reference to distortion and compared with cameras that can
biological and physical science answers preferred

Answer 1

because we do not live underwater

Answer 2

well, the eye does adapt to seeing underwater, that's how little kids play games and get stuff off the floor of "the deep end" but the movement in the water makes the actual stuff in front of you SEEM distorted because of the way light bends throughout the water. It's the same way fish's see- there is no way to adapt an eye of any creature to see past moving water all around them to a clear object.

Answer 3

The power of any lens depends on several things: the material the lens is made from (specifically the index of refraction of the material), the curvature of the lens, and the surrounding medium (specifically its index of refraction).
The eye is a lens, so its power is determined by those 3 things. When your eye is in water the surrounding medium has changed (on land the surrounding medium is air), so the power of your eye changes.
This explains why nearsighted people actually see better underwater -- their eye's power has changed for the better!
Underwater cameras are designed with these factors in mind. If the camera is fixed-focus (like the disposable cameras), pictures taken out of the water will be blurry.

Answer 4

The lense of your eye is designed to focus the light that you receive onto your retina. biologically we live above water and thus the focul point of the eye is based on the light hitting your eye from a dry medium such as air.

When light hits the lese of your eye it bends and focusses for two reasons, one is the shape of the lense the other is the change in mediem between the air and your eye.

Look at a stick half in and half out of the water, see how it looks to bend. the light is refracted as it leaves the water because the light has different physical properties in air than water (velocity)

This is what happenss at your eye between air and water (eye) but if you are under water the light reacts differently at you eye and focuses on the wrong point.

If you put goggles on you now recreate the air/eye contact and though you will get some distortion as the light in the water hits your goggles full of air, you will not lose focus on your retina as this has the biologically expected and adapted air/water (eye) contact

Answer 5

there is no selective advantage for humans to evolve sight under the water, it places limitating factors on the ability to see out of water. This is because water seeing eyes have large pupils to let the light in as there is less light in the sea river etc. Also there is an ideal amount of diffraction of the light when it travells throught the air into the conjuctiva (excuse spelling), this diffraction is dependant on the difference of densities of the mediums our case air to eye but in the water it is water to eye. As water is more dense than air this changes the angle of the light and causes short sighted. When looking at amphibious aminals eg penguins it can be seen that there eyes are adapted to land vision but have large pupils for when they go in the water.

In conclusion we have had no need over the past 5 million years or so to evolve aquatic eyes there is no advantage in having them and the cost of that adaption is too great due to natural selection.

Answer 6

I dont honestly know the answer to this question as its not my topic of expertise, but in my own experience-i am unfortunately, very short sighted (so wear contact lenses)

I am on prescription -4.75 in each eye, which is quite poor for my age, and something ive inherited unfortunately from other members of the family! Im the unlucky one i guess in that respect!

however i have found that ont he times that i did not wear my ocntact lenses to the swimming pool-when i had water in my eye, the water distorted my lens-so allowing me to see clearly again.

It may sound silly but i thought this was fascinating as for a brief moment swimming every now and again i had 10/10 vision!

So this has int he past lead me to presume that water disorts the lens, or other parts of the eye-either to create a clear picture (if your eye is short sighted like mine) or a distorted picture (if your eye was otherwise near perfect and you didnt need contacts or lens!)

i hope this makes sense, this is just from my own experience but i am fascinated by science and biology, so i tend to make my own presumptions sometimes!! :)

x

Answer 7

Someone shortsighted sees better underwater, someone with normal vision or longsighted might see worse I think, its to do with the way light reflects in water or something like that? Over 5yrs since I did GCSEs but we were taught something along those lines. Light rays bend further in water... I might be talking rubbish...

Answer 8

Our ancestors did not move to the water, so we did not evolve eyes adapted to the density of the media. Air is less dense, and our eyes adapted to it

Answer 9

firstly, the human eye isnt adapted to underwater viewing because we dont live underwater.

secondly, size and distance are amplified underwater (to our eye) as we are use to viewing through air. for example, fishes and sharks look much bigger than they really are. so when a diver says he came face to face with a 10ft long shark, it was probably only about 6ft.

Answer 10

Actually the eye is adapted to see underwater its the perspective which you are not used to

Answer 11

Are you sure you can't see under water? I like to swim in both sea and lakes and I have no problem to see under water. Is there something wrong with me?