Movements of the eyes

1
Movements of the eyes
The muscles were of necessitie provided and given
to the eye, that so it might move on every side
for if the eye stoode faste and immoveable, we
should be constrained to turne our head and necke
(being all of one peece) for to see but by these
muscles it now moveth it selfe with such
swiftness and nimbleness, without stirring of the
head as is almost incredible... A. Du Laurens
(1599) A Discourse of the Preservation of Sight
of Melancholike Diseases of Rheumes, and of Old
Age
2
One degree from the center of the fovea (1 degree
width of finger at arms length), visual
acuity is less than half of what it is in the
fovea. So saccadic eye movements shift the
center of gaze around the image.
Eccentricity
3
Vision is an active process. Binocular vision
afforded by aligning the eyes provides depth
signals necessary for capturing things in the
environment.
4

• Six extraocular muscles rotate the
• eyes.
• Types of movements of the eyes
• Gaze shifting
• Saccade
• Pursuit
• Vergence
• Gaze holding
• Vestibular-ocular reflex
• Optokinetic reflex

5
A neuron producing movements of the eyes
6
Brainstem Saccade Generator
100 msec
7
Brainstem Saccade Generator
Eye position
100 msec