I recently watched an interesting video by the Exploratorium. Rose, one of their explainers (people who explain science to their visitors) was dissecting a cow eye. She explained that as the cow eyeball is similar to that of the human eyeball, the dissection will help to explain how our eye works. I thought it was a really cool video, but considering that some people may be a bit grossed out by it, I have decided not to share the video directly, but write a brief blog post about it instead.
Before the dissection, Rose talked about the muscle tissue around the eye that helps it rotate, fat tissue which cushions the eye, and the optic nerve that connects to the brain.
She talked about the cornea and its function, how it protects the eye and how it does the majority of focusing for the eye (70-80 percent). She also talked about the iris ring right behind the cornea, which is actually a type of muscle that can contract and expand depending on the environment to control the amount of light that gets through the pupil. For example, when the environment is very bright, the iris ring will contract around the pupil to reduce the amount of light that gets into the back of your eye. When it is dark, the iris ring will open up so that more light can get in and you can see better.
Another interesting thing Rose touched on is melanin, the brown pigment that can be found in the iris of the eye, which can also be found in our hair and skin. If you have more melanin, you get darker hair, darker iris and your skin tone is darker. This acts as a natural sunblock, and it means you will be less likely to get sunburnt.
Rose also shared another interesting fact about our retina at the back of the eye. Many of you would probably know that the retina is made up of photo receptors (light receiving cells) which help us to see. But did you know that there is one point where there is no photo receptor? That point is called the optic disk, and it has no receptor because it is the point at which the optic nerve passes through the retina and the back of the eye. Without photo receptors, this is also the blind spot of the eye. Yet, interestingly, we do not see a blind spot because the two eyes cover for each other, and the brain just fills in the missing info. It is also necessary that the retina be attached properly to the back of the eye in order for us to be able to see. That is why if a person is hit on the back of the head such that the retina is detached from the back of the eye, he or she might lose their vision!
The 13-minute video covered all parts of the eye functions quite thoroughly. After reading all these, if you are interested enough, you can find it here.