Eye Facts

Do you know that…

Length of eyeball = 24.5mm

Volume of eyeball = 5.5mL

Weight of eyeball = 7.5g

Average time between blinks = 2.8s

Thickness of cornea = ~0.5 mm in center; ~1 mm in periphery

Diameter of cornea = 11.5mm

Thickness of lens = 4mm

Diameter of lens = 9mm

Composition of lens = 65% water; 35% protein

Number of retinal receptor cells = 5-6 million cones; 120-140 million rods

Number of retinal neural cells = 800 thousand to 1 million

Number of fibers in optic nerve = 1,200,000

Wavelength of visible light (human) = 400-700nm

Highest density of rods = 160,000/mm2

Peak density of rods (cat) = 400,000/mm2

Density of cones = 200,000/mm2

Intraocular pressure = 10-20mmHg

Turnover of aqueous humor = 15 times/day

More Facts and Figures about the Human Retina are available from WebVision.

Other references:

(Schiffman, H.R., Sensation and Perception. An Integrated Approach, New York: John Wiley and Sons, Inc., 2001)
Foster, C.S., Azar, D.T. and Dohlman, C.H. Smolin and Thoft's The Cornea. Scientific Foundations and Clinical Practice, 4th edition, Philadelphia: Lippincott Williams & Wilkins, 2005