The idea for the general principle of a contact lens was made by Leonardo da Vinci in 1508.

Swiss physician A.E. Fick is credited with fitting the first glass contact lens in 1887.

The cornea is the only living tissue in the human body that does not contain any blood vessels.

The cornea has 5 separate layers.

The retina has 10 separate layers.

The little lights you see with your eyes shut are phosphenes, which come about when you shut your eyes tight.   This is because the retina is stimulated by pressure on your eyeball.

The space between your eyebrows is called the glabella.

Eyeballs are the second most complex organs you possess, next to your brain.

The eyeball can instantaneously set in motion hundreds of muscles and organs in your body.

Of all the muscles in your body, the eye muscles are the most active.

The adult eyeball measures about one inch in diameter.  Of its total surface area, only one-sixth is exposed "“ the front portion.

It can be uncomfortable to sit too close to a television, but your eyes will not be damaged by doing so.

The pupil expands as much as 45% when a person looks at something pleasing.

In a normal lifespan, your eyes will bring you about 24 million images of the world around you.

Babies cry but don't produce tears until they're one to three months old.

A cow's cornea has seven to eight layers of material to protect its eye while grazing close to the ground.

We all have microscopic creatures lurking in our eyelashes.

Under the right conditions, you can discern the light of a candle at a distance of 14 miles.

Your eyes are always the same size from birth, but your nose and ears never stop growing.

A child's vision system isn't completely developed until the age of nine.

Dogs are unable to tell the difference between the colors red and green.

The giant squid has the largest eyeball on earth.   At 18 inches across, it's about the size of a beach ball.

It is impossible to sneeze with your eyes open.

Clayton Grinage, COE

Lead-based eye makeup used by ancient Egyptians appears to have had antibacterial mechanisms that may have helped prevent common infections, said researchers from Paris' École Normale Supérieure in a news report.

In a study originally published in Analytical Chemistry, Christian Amatore, Ph.D., and colleagues used electron microscopy and X-ray diffraction to assess 52 samples from containers of preserved makeup at the Louvre. 

The makeup consisted primarily of four lead-based chemicals: galena, cerussite, laurionite, and phosgenite, the researchers said in the news report. Due to deterioration of the makeup samples over the centuries, the researchers were unable to identify what percent of the makeup was lead.

The researchers contend that during periods in which the Nile River flooded, the population was particularly vulnerable to infections caused by particles that entered the eye, causing inflammation. 

The dosage of lead in the makeup was a key factor in its potential benefits, Dr. Amatore said in the news report.

Source: Latif, E., & Dalton, M. (2010). Lead-based eye makeup may have fought infection in ancient Egypt. EyeWorld Week, 15(4). Retrieved from http://www.eyeworld.org/ewweek.php?id=578#7

Did you know that aspen trees have eyes? And not just two, but many of them? The eyes are the result of self-pruning, or atrophy, and the falling off of branches as the trees race upwards toward the sun. Here is a gorgeous example I saw on my recent trip to Utah.

Ilya Rozenbaum MD