PARTS OF THE EYE
The Cornea

Transparent “window” at front of the eye;
allows light to pass into eye
http://www.stlukeseye.com/anatomy/Cornea.asp
The Pupil

Opening in center of iris that helps regulate
amount of light passing into rear chamber of eye


Bright light – pupils constrict; less light, sharper image
Dim light – pupils dilate (open); more light; less sharp
http://www.stlukeseye.com/anatomy/Pupil.asp
The Iris

Colored ring of muscle surrounding pupil –
controls light levels inside eye
http://www.dpreview.com/reviews/olympuse500/
http://www.stlukeseye.com/anatomy/Iris.asp
The Lens
Transparent structure that
focuses light rays falling on the
retina

Accommodation – curvature of
lends adjusts to alter visual focus

Nearsightedness – close
objects seen clearly, distant
objects blurry

Farsightedness – distant
objects seen clearly, close
objects blurry
http://www.stlukeseye.com/anatomy/Lens.asp
http://www.patfullerton.com/superman/pix/cl
ark/clark1987b.html

The Retina

Neural tissue lining back
surface of eye



Absorbs light
Processes images
Sends visual info to brain

Optic Disc – hole in retina
where optic nerve fibers exit
eye

Optic Nerve – connects eye
w/ brain
http://www.stlukeseye.com/anatomy/Retina.asp
http://www.stlukeseye.com/anatomy/OpticNerve.asp
X
X
Rods & Cones

Cones (6 million in eye) –
specialized visual receptors for
daylight & color vision
- Sharper, more detailed image than
rods


Fovea – spot in center of retina
 Contains only cones
 Greatest point of visual acuity
Rods (125 million in eye) –
specialized visual receptors for
night and peripheral vision
http://www.cis.rit.edu/people/faculty/montag/van
dplite/pages/chap_9/ch9p1.html
http://www.stlukeseye.com/anatomy/Fovea.asp
Sensory Adaptation

What are common examples of sensory
adaptation?

Why don’t objects disappear from our
vision over time?

Sensory Interaction

How do our senses influence one another?
 The
McGurk Effect
Dark & Light Adaptation

Dark Adaptation – process in which eyes
become more sensitive to light in low
illumination
(entering a movie theater)

Light Adaptation – process in which eyes
become less sensitive to light in high
illumination
(leaving a movie theater)
http://www.picturehistory.com/find/p/902/mcms.html