The Human Eye

With over 100,000 movements per day, our eyes are the most active muscles in our bodies.  They are also the fastest reacting muscles in the body, with the ability to contract in less than 1/100th of a second.

We use our eyes every second of our waking life, but seldom appreciate how much we rely on them.  By understanding our eyes better, we stand a better chance of retaining vision, productivity and functionality well into old age.


The human eye is an amazing machine.  It captures light and turns it into images to be interpreted by our brains.  Our eyes allow us to recognize faces, perceive danger, and appreciate beauty.  Here are some of the basic elements of the human eye:

Cornea – The window to the world.  When light rays enter the eye, the cornea refracts the light so that the rays can pass through the pupil.

Iris – The colorful ring around the pupil that we refer to when describing the color of eyes.  By dilating and constricting, the iris controls the light levels inside the eye - similar to the aperture on a camera.

Pupil – The black center of the eye - works with the iris to regulate the amount of light entering the eye.

Lens – The clear, flexible area behind the pupil that fine-tunes light for the retina.  Flexible nature allows it to shorten and lengthen the focal length (and thus the focal point) of light passing through.

Vitreous Humor – The gel-like material that helps the eyeball retain its shape and firmness.

Retina – Sensitive nerve tissue that lines the rear wall of the eye.  Converts finely focused light into electrical impulses to be translated by the brain.

Sclera – The white of the eye.  Provides structural strength and protection for the inner elements of the eye.

What Can Go Wrong?

Eye problems are either hereditary or environmental.  There’s not much you can do about inherited disorders like congenital amaurosis (color blindness), but you can actively protect your eyes from environmental risks.

The obvious threat is foreign objects coming into physical contact with the eye.  The eye is a complex and productive organ, but it is very delicate.  Even a tiny scratch or scar on the cornea can cause impaired vision.  Most industrial workplaces require employees to wear safety goggles to protect them from particulate exposure.  Errant sparks, metal shavings or splintered wood chips can result in permanent damage.

Employees outside of the industrial realm experience a less obvious danger.  Eyestrain can cause debilitating headaches and blurred vision, and prolonged strain can result in advanced macular degeneration (a disease of the retina).  This degenerative disease disrupts essential components of vision such as the ability to read, focus on objects, or adjust to changes in light.

What’s All the Hype About Blue Light?

Natural light helps our bodies regulate sleep cycles and is commonly associated with positive feelings, effective memory, and good health.  However, when you’re in an enclosed office space 40 hours a week, you may not have access to much natural light.  It is critical that office lighting is designed to cater to employee circadian health.

In 2008, international vision product company Essilor partnered with the Paris Vision Institute in a study where technicians split visible light into various light bands to find out which wavelengths are the most harmful to the human eye.  Each light band was focused on retinal cells over a period of hours.  They identified the blue-violet band (at a range of 415 nm to 455 nm) to be most destructive to retinal cells.  This is the same spectrum produced by the sun, office lighting, and electronic devices.

Blue light (commonly found in fluorescent bulbs, tablets, computers screens and phones) is fine for a few hours a day – it can even leave you feeling alert and awake.  However, prolonged exposure to the blue light spectrum has been linked to:

• retinal cell death
• sleep and immune system disorders
• obesity
• cardiovascular diseases
• diabetes
• osteoporosis
• breast cancer

If you have an iPhone and you haven’t already done so, go into Settings > Display & Brightness and turn on Night Shift.  It will automatically adjust the color temperature of your phone to sync with the natural daylight schedule in your area.

It goes without saying that you should not stare into the sun (but just in case) – UV light affects the cornea and can lead to cataract formation.  Less obvious, however, is the fact that fluorescent lamps also emit UV light (don’t stare into those either).

Prolonged exposure to blue light results in cell damage and death.  Some of the symptoms of advanced macular degeneration are reduced central vision, difficulty adapting to dimly lit rooms, blurriness, muted color perception, difficulty recognizing faces, visual distortion, depression and hallucinations.  In fact, symptoms like nearsightedness, eyestrain, poor sleep patterns and prolonged bad mood could all be the result of a poorly-lit environment.


Proper eye protection helps block out harmful UV rays and blue light from the sun, but what about indoors?  Are you supposed to wear sunglasses all day at the office?  If you can pull it off…

For everyone else, turning down the brightness on your computer and other devices helps.  New smart-controlled, color changing LED lighting systems can also help ensure your work space isn’t damaging your eyes.

More Science!

Millions of photoreceptor cells called rods and cones are woven into the retina.  Cones are what give us a spectrum of color to enjoy, and let us appreciate the finer details of a painting or carved woodwork.  There are 6-7 million cones divided into red, green, and blue.

Rods are much more light sensitive than cones, but only detect monochrome.  Approximately 120 million rods dominate our night vision, peripheral vision, and motion detection.  They adapt slowly to changes in light – it takes the human eye about 30 minutes to reach optimal night vision in the dark.  Being 1,000 times more sensitive than cones, rods can pick up dim objects like distant stars.  

Light can travel over a trillion miles before being picked up by our eyes and converted into an image in just a few inches of space.  Let’s continue to collect light from our past, and protect our eyes into the future.

View References

Got feedback?

contact us
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.