Weekly Online Lesson Online Lesson Archive Grade Level: 5-10 Subject: Anatomy/Health

Growing Eyeballs

According to a Kyodo news agency report on January 5, 2002, Japanese scientists have succeeded in growing the world's first artificial eyeballs. A group of biology researchers at Tokyo University, succeeded in growing eyeballs in tadpoles using cells taken from frog embryos.

The group collected undifferentiated cells from the embryo of a Platanna frog and then soaked them in a special medium. The cells were then transplanted into the eyeball of a tadpole whose left eye had been removed before it was hatched. A week after the transplant, Asashima’s group confirmed the tadpole’s eyeball was connected to the optic nerves and there were no rejection symptoms.

In this week's online lesson you will learn more about vision and the anatomy of the eye. Will forget about the tadpoles for now and focus on the human eye.

How We See

How is the eye able to turn light signals into impulses the brain can interpret? The eye is truly our most remarkable and complex sensory organ. To learn more about the anatomy of the human eye and how it works, visit Anatomy of the Eye from the Macula Foundation. You'll find three great resources here to look at. First click The Eye, which shows you a cross-sectional view of the eye and explains the basic structures or parts. Click each of the blue links to the left of the eyeball starting with cornea. The graphic will highlight that part and give you a brief description below.

When you have learned about each structure, click The Retina in the navigation bar on the left. This page works the same way: start with photoreceptor and study all of the structures.

Return to the main Eye Anatomy page and watch the structures of the eye video by clicking the link. This short QuickTime video takes you on a narrated journey inside the eye, focusing (no pun intended) on the health of the macula.

What is the function of the optic nerve? Describe vitreous. Which visible part of the eye determines our eye color? Rods and cones belong to which structure of the eye? What is the white outer part of the eye called?

To learn more about the workings of the eye, visit Eye Anatomy from St. Luke's Cataract & Laser Institute. We've already covered some of this information, but keep reading as the page explains how the eye produces a visible image. When you reach the bottom of the page take the Eye Anatomy Quiz. Choose the correct answer for each of the five questions and then click Score Me to see your score below.

Vision Problems and Diseases

If you wear glasses or contact lenses, you are already aware of at least one form of vision disorder. Three disorders are fairly common: farsightedness, nearsightedness, and astigmatism. Other disorders, like glaucoma, are less common but can have serious complications including loss of vision. To learn about vision problems and eye disorders visit How Your Eye Works at seeclearly.com. Read this page and then click each of the three common disorders in the tabs near the top: Farsightedness, Nearsightedness, and Astigmatism. On each of these pages you will see a cross-section of the misshapen eye with a description of the result. Below the eye diagram is a picture. Roll your mouse over the picture to see the effect each disorder has on vision. Which disorder would make it hard to read a newspaper? Which would make it hard to watch a football game? Which would make it hard to drive?

Return to the How Your Eye Works page and click eye disorders. Read the brief description of each of the disorders listed. Of the disorders and diseases listed, which seem to be the most serious? Which is the least serious? Which is the most treatable? Which disorders are preventable with early detection and treatment? Which can lead to vision loss?

Optical Illusions

You shouldn't always believe what you see. That's the lesson you will learn from these next two sites. Both feature fun and often fascinating drawings or pictures designed to play tricks your mind. The first site is called eyetricks.com. Start with the Optical Illusions galleries on the top of the left navigation bar. Click Image Gallery #1 to open the first gallery. Why is it so hard to count the number of black dots? Click Next below each image to go to the next optical illusion. Try each gallery.

Now that you can no longer believe your eyes, Try the 3D Images links (lower on the left navigation bar), starting with the Stereogram Gallery. Stereograms are 3D images hidden inside another picture or pattern. Just cross your eyes a little until the images emerge. Pick five or six from the list to look at. If you need help seeing the 3D images follow the tips for viewing below the list.

Once you've got the hang of these, click Online Stereogram Generator to make one of your own. Type a word in the Hidden Word field and click Go.

If you're still having trouble, try the How to See 3D page at the optometrists network. All you have to do is connect the dots as this page explains parallel and cross-eyed 3D viewing. Learn more at this site by reading 3D Glossary: Image Types. Then have more fun at the 3D Art Gallery. You already know about hidden image stereograms, but try out the Stereo photographs by clicking cross-viewing or parallel-viewing.

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