Heterophoria Flashcards
normal binocular vision
- both eyes simultaneously cooperating
- single perception of object
- fusing of images from the 2 eyes
sensory fusion
integration of similar images at the cortex
motor fusion
- motor alignement to sustain binocular vision
- tries to eliminate disparities of 2 images
- tries to FUSE as best as possible to make one image
- NEEDS vergence to produce one image
convergence
tries to maintain binocular vision by ensuring images are on corresponding retinal areas of the eye so there is no disparity
NPC
closest distance where the eyes can converge and maintain binocular vision
cover-uncover
- presence of deviation ( ONLY DETECTS TROPIA)
- lateralitly
- frequency (constant/intermittent)
intermittent tropia
shows when dilated or tired
if there is ANY movement in cover/uncover…
tropia only
alternating cover test
- direction
- magnitude
- distance and near
Why is phoria only present on alternating cover test>
because fusion is broken
heterophoria
tendency of the eyes to deviate when fusion is blocked
-when there is something to focus on, there is no tendency to deviate
visual axes
from the fovea to the point of fixation
symptoms associated with heterophoria if fusional amplitudes are not enough
- convergence insufficiency
- convergence excess
- divergence insufficiency
- divergence excess
measurement of phorias and tropias
at distance and near
maddox rod
used to measure horizontal and vertical phoria
rod dissociates the eye