Eyes

Fastest Reacting Muscle

• The eyes have the fastest-reacting muscles in the whole body. It contracts in 1/100th of a second (1^✔ ✔Trusted Source
  Strabismus and eye muscle function
  
  Go to source).
• The eyes contain more than 50% of the sensory receptors in the human body (2^✔ ✔Trusted Source
  Anatomy, Head and Neck, Eye
  
  Go to source).

Cornea

• The cornea is clear and covers the colored iris and pupil.
• The cornea is the only part of the human body that doesn’t contain blood vessels (3^✔ ✔Trusted Source
  Absence of blood and lymphatic vessels in the developing human cornea
  
  Go to source).

Eye Blinking

• The average adult blinks 12 times per minute.
• When we blink, we close our eyes for 0.3 seconds (4^✔ ✔Trusted Source
  High-speed camera characterization of voluntary eye blinking kinematics
  
  Go to source).

Size of the Eyeball

• The diameter of an adult eyeball is around 2.5 cm.
• The human eyeball is 24.5 mm long (5^✔ ✔Trusted Source
  Variations in Eyeball Diameters of the Healthy Adults
  
  Go to source).

Eyelashes

• Eyelashes grow at a rate of 0.12 to 0.14 mm per day.
• There are about 90 to 160 lashes on the upper eyelid and 75 to 80 lashes on the lower eyelid.
• It takes about eight weeks for lashes to grow back after being pulled out (6^✔ ✔Trusted Source
  Anatomy, Head and Neck: Eyelash
  
  Go to source).

Lens

• The lens of the human eye is composed of 66% water and 33% protein (7^✔ ✔Trusted Source
  Lens Protein
  
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Color Blindness

• Color blind people find it hard to distinguish colors like green and red (8^✔ ✔Trusted Source
  Types of Color Vision Deficiency
  
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• At birth, everyone is color blind (9^✔ ✔Trusted Source
  Infant color perception: Insight into perceptual development
  
  Go to source).

Eye Color

• Iris determines the color of the eye.
• Brown is the most common eye color in the world (10^✔ ✔Trusted Source
  Molecular and biochemical mechanisms of human iris color: A comprehensive review
  
  Go to source).

Retina

• The retina plays a vital role in vision by capturing the light that enters your eye and translating it into the images you see (11^✔ ✔Trusted Source
  Anatomy, Head and Neck: Eye Retina
  
  Go to source).

Rods and Cones in the Retina

• Retinas consist of light-sensitive cells called rods and cones. Rods register the shapes of images and respond to low levels of light while cones respond to bright light and register the color of images (12^✔ ✔Trusted Source
  Molecular bases of rod and cone differences
  
  Go to source).
• The retina has about 6 million cones and over 100 million rods.

Tears

• Newborns will cry out without tears for the first three to six weeks (13^✔ ✔Trusted Source
  How Tears Work
  
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• Tears help protect our eyes from infection and irritation (14^✔ ✔Trusted Source
  Older adults have less tear production. Aging: A Predisposition to Dry Eyes
  
  Go to source).