VISIONthe sense we rely on most

often

  

Photoreceptors in the eye are sensitive to wavelengths of light energy called the visible spectrum

Structures of the Eye

Structures of the Eye

Structures of the Eye

vitreous

Structures of the Eye

iris vitreous

Structures of the Eye

cornea

vitreous iris

Structures of the Eye

pupil

vitreous iris

cornea

Structures of the Eye

lens

vitreous iris

cornea

pupil

Structures of the Eye

retina

vitreous iris

cornea

pupillens

Structures of the Eye

Optic nerve

vitreous iris

cornea

pupillens

retina

Structures of the Eye

Function of Eye Structures

Function of Eye Structures

• Lens – focuses the image on the retina

• Iris – pigmented muscle that give the eye its color and regulates the size of the pupil

• Pupil -- not a structure, but an opening in the iris

• Cornea – transparent portion of the sclera through which light enters

Function of Eye Structures

• Retina – layer containing photoreceptors that transduce light energy into a nerve impulse

• Rods – photoreceptors that are unable to detect color, but work well in low light

• Cones – photoreceptors that detect color in bright light but not in low light

Location of Rods and Cones

CCCC

Function of Eye Structures

  

The macula is located roughly in the center of the

retina. It is a small and highly sensitive

part of the retina responsible for

detailed central vision. The fovea is the very center of the

macula.  

Vision Problems• Glaucoma – pressure build up inside

the eye causes damage (a leading cause of blindness around the world)

• Color Blindness – genetic deficiency in the cones, most common form is red/green color blindness (inability to distinguish between reds and greens)

• Cataracts – clouding of the lens

Vision Defects in Focusing

• Myopia = nearsighted due to an elongated eyeball

• Requires a concave lens to correct

Vision Defects in Focusing

• Hyperopia = farsighted due to a shortened eyeball

• Presbyopia = farsighted due to aging• Farsightedness requires a convex

lens to correct

Vision Defect in Focusing

• Astigmatism = due to a misshapen cornea, part of the image is focused and part is not

• Requires a non-symmetrical lens to correct