What’s wrong with that eye?
by ryan
I was dissecting a cow’s eye-ball today and there were two lovely elderly women who were very curious about various eye problems. I feel like those are questions that I get very often and don’t really have good answers. So I went to the Exploratorium’s most valuable resource: the people milling about the coffee machine and microwave in the lounge.
Charlie C. gave me some great info and I wanted to share some of the most common disorders I get asked about and post them as a reference so we can be better eye-ball-cutter-upper-people.
Glaucoma has to do with having too much pressure in the eye. One of the reason it may happen is if the aqueous and vitreous humors don’t get replenished adequately. Interestingly enough, the pressure hurts the optic nerve, causing the neurons to stop functioning. The happens very gradually and from the outside in, so that sometimes people don’t notice how their field of vision is getting smaller and smaller.
Check out the difference in these two photos to get an idea of the changes. 
Cataracts on the other hand form in either the cornea or the lens. They are opaque spots of denatured protein that cause cloudy dots in the visual field. Huh? Charlie said that one can thin of protein denaturing as similar to how the protein of an egg white turns white or cloudy when cooked. But cataracts happen for various reasons including age, genetics, and exposure to radiation. Cataracts are the leading cause of blindness in the world.
Detached Retina happens when that gooey pinkish grey blob (as I like to call the retina) becomes separated. It can happen for various reasons including trauma to the eye. Wikipedia says it peels like a bubble in wallpaper. Yummy! Many times it requires surgery, but apparently some minor cases can be cured by simply lying down and looking up.
Davie Bowie’s Eyes When Bowie was age fifteen, his friend, wearing a ring on his finger, punched him in the left eye during a fight over a girl. Bowie was forced to stay out of school for eight months so that doctors could conduct operations in attempts to repair his potentially-blinded eye. Doctors could not fully repair the damage, leaving his pupil permanently dilated. As a result of the injury, Bowie has faulty depth perception. Bowie has stated that although he can see with his injured eye, his color vision was mostly lost and a brownish tone is constantly present. The color of the irises is still the same blue, but since the pupil of the injured eye is wide open, the color of that eye is commonly mistaken to be different (Wikipedia).
Field Trip Explainers 
Another interesting eye fact / complete tangent brought to you from my neuroanatomy class / how to tell if your girlfriend is faking her orgasms:
So one of the exhibits in the mind section talks about how poker players will watch other player’s pupils to see if they’re lying. This works because the sympathetic nervous system gets activated when you are excited. You see, the nerves that leave your brain and innervate your organs fall into two categories, called sympathetic and parasympathetic. In class we learned the mnemonic “point and shoot,” to help us keep them straight, because arousal involves the parasympathetic system, while orgasms happen when the sympathetic system is activated. (Really, I swear, any medical student would know that too.) Anyway, the pupils are also controlled by this system, so stimulating the sympathetic system will cause your eyes to dilate. Therefore (here’s the point really), people’s eyes will dilate when they are really excited. If you want a demonstration look someone (most likely your significant other who won’t be too weirded out by your overly curious and intent gaze) in the eye while they orgasm; it’s fascinating.
PS: We don’t try that at cow dissection, but I do have kids look at each other while they look up at the light and then shade their eyes. That’s fun.
whatcha doin out ther man? that’s pretty freaky bowie…
Check out this website that simulates what the world (literally)
looks to a person with colorblindness. I think somewhere on the site there’s also the ability to take your photos and convert them to match different red/green deficiencies.
http://www.vischeck.com/examples/