Introduction Flashcards
Bin
Two
Oculus
Eye
Coordinate use of BOTH eyes to produce single mental image
Binocular vision
blending of sight to form single percept
Fusion
ESSENTIALS FOR BV
Healthy functioning maculas
Efficiently working muscular mechanism
Efficiently working neural mechanism
Proper coordination of eyes and brain
Neuroplasticity
PREREQUISITES FOR BV
Frontally placed eyes, overlapping retinal fields.
Partial decussation of the optic nerve fibers.
Foveal region stimulate.
Corresponding or identical points.
Size of retinal images.
Efficient function of extra ocular muscles and nerves
Advantages of BV
Single vision.
Optical defects in one eye are made less obvious by the normal image of the other eye.
Enlarged field of vision.
Power to discriminate details and contours of an object is better with two eyes than with one eye alone.
Loss of one eye will not seriously handicap the individual.
Stereopsis or depth perception
Compensation of blindspot and other differences
At birth
Eyes are not associated with each other; act as two different organs
VA: not greater than 5/200; normally hyperopic
First sign of the development of fixation appears when the eyes follow light
Newborn
Eyes follow large objects
2 months
At 3 months:
Foveas are fully formed
They hold objects
Eyes are expected to be straight
3-4 months
6 months
Fixates at an object for 1-2 minutes
VA: 20/70
1 year old
Fusional mechanism becomes fully developed
1- 1 ½ year old:
VA: 20/20
Accommodation develops with sharpening of visual acuity
3 years old
ADDUCTION
movement of one eye inwards
movement of one eye outwards
ABDUCTION
movement of one eye upwards
SUPRADUCTION
INFRADUCTION
movement of one eye downwards
movement of one eye only
DUCTION
movement of the vertical corneal meridian of one eye outward
EXCYCLODUCTION
movement of the vertical corneal meridian of one eye inward
INCYCLODUCTION
synchronous and symmetric movement of both eyes in the same direction
Version
both eyes to the right
Dextroversion
LEVOVERSION
both eyes to the left
both eyes looking upward
SUPRAVERSION/ANAVERSION/SURSUMVERSION
both eyes looking downward
INFRAVERSION/CATAVERSION/DEORSUMVERSION
both eyes to the right & up
DEXTROSUPRAVERSION
DEXTROINFRAVERSION
both eyes to the right & down
both eyes to the left & up
LEVOSUPRAVERSION
synchronous and symmetric movement of both eyes in the opposite direction
Vergence
movement of both eyes inward
CONVERGENCE