Note: The above is an embedded image from the Reddit.com website. It may stop working over time. If that has happened I apologise but I have no control over it. And I won’t know about it unless someone tells me.
Here is the same picture sharpened up a bit. The blacks have been deepened too. And this picture is on my site so it won’t disappear.
The picture is nice in that you can see the crystal clear, domed cornea and the flat iris and and the slit for an aperture (pupil). You can’t see the lens because it is beyond the pupil and partly behind the iris. The photo has been moved through 90 degrees clockwise so that the cat looks up. The cat as actually looking straight ahead. The cat must be a regular (random bred or moggie) brown tabby.
Some information about the feline eye
Cats don’t see what humans see in terms of color and sharpness but they have decent eyesight in general and specifically, as you no doubt know, they can see well in the dark because they have a lot of light detection cells in the retina called ‘rods’ which are sensitive under low light conditions but the image formed tends towards black-and-white. This inherited attribute has evolved because the cat is essentially crepuscular – hunts at dawn and dusk mainly because that’s when prey is about. So the cat hunts when it is dark. They need super night vision and they have it.
The cornea you see here, as mentioned, is beautifully clear. The cornea’s function is to firstly let light into the eye and cover the pupil, iris and the fluid-filled interior of the eye. It also has the function of bending light and focusing it. It is responsible for focusing through refraction most of the light (65-75 percent) entering the eye onto the retina. The lens which is out of sight in the photo does the rest of the focusing. The retina coverts the light into electrochemical signals which are transfered to the brain by the optic nerve which comes out of the back of the eye.
If the cornea becomes inflammed the condition is called ‘keratitis’ or a corneal ulcer. It causes blurred vision. The cause is usally injury or infection. A cat with keratitis will show signs of discomfort as it is painful; squinting, tearing and discharges from the eye. The cornea becomes less transparent leading to partial or complete blindness. It can be managed by a vet. See your vet about it.
Cataracts affect the lens which becomes opaque. They are rare in cats and are normally caused by injury or infections.
Sources: Myself, the internet (various sources) and Cat Owner’s Home Veterinary Handbook.