Heterophoria Flashcards

1
Q

normal binocular vision

A
  • both eyes simultaneously cooperating
  • single perception of object
  • fusing of images from the 2 eyes
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2
Q

sensory fusion

A

integration of similar images at the cortex

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3
Q

motor fusion

A
  • 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
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4
Q

convergence

A

tries to maintain binocular vision by ensuring images are on corresponding retinal areas of the eye so there is no disparity

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5
Q

NPC

A

closest distance where the eyes can converge and maintain binocular vision

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6
Q

cover-uncover

A
  • presence of deviation ( ONLY DETECTS TROPIA)
  • lateralitly
  • frequency (constant/intermittent)
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7
Q

intermittent tropia

A

shows when dilated or tired

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8
Q

if there is ANY movement in cover/uncover…

A

tropia only

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9
Q

alternating cover test

A
  • direction
  • magnitude
  • distance and near
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10
Q

Why is phoria only present on alternating cover test>

A

because fusion is broken

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11
Q

heterophoria

A

tendency of the eyes to deviate when fusion is blocked

-when there is something to focus on, there is no tendency to deviate

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12
Q

visual axes

A

from the fovea to the point of fixation

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13
Q

symptoms associated with heterophoria if fusional amplitudes are not enough

A
  • convergence insufficiency
  • convergence excess
  • divergence insufficiency
  • divergence excess
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14
Q

measurement of phorias and tropias

A

at distance and near

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15
Q

maddox rod

A

used to measure horizontal and vertical phoria

rod dissociates the eye

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16
Q

maddox rod phoria test (in space)

A

need: penlight, madox rod, prisms
- done cc
- hold penlight 40cm for near
- have pt look at muscle light for distance
- hold maddox rod over OD

17
Q

horizontal phoria

A

the grooves on the maddox rod are oriented horiztonally. The pt will see a vertical streak

18
Q

vertical phoria

A

the grooves are oriented vertically, giving a horizontal streak

19
Q

red line through the white light

A

ortho

20
Q

red line to the right of the light

A

eso, uncrossed diplopia

21
Q

red line to the left of the light

A

exo, crossed diplopia

22
Q

red line below the light

A

right hyper

23
Q

red line above the light

A

left hyper

24
Q

suppression

A

active deactivation of a retinal image in one eye by the visual cortex
-brain prefers to suppress and provide vision as close to binocular vision as possible

25
Q

alterante suppression in W4D

A

can see 3 then 4 dots

include when recording

26
Q

prims for R hyper

A

BU over OS

27
Q

prism for L hyper

A

use BD over OS

28
Q

Can maddox rod differentiate phoria from tropia?

A

no

29
Q

example of recorded maddox rod

A

DLP with red cc 4 XP, DVP ortho

NLP with red sc 5 XP, NVP 4 R hyperphoria

30
Q

expected findings in maddox rod

A

1 prism D to +/- 2 prism D at D

3 prism D +/- 3 prism D at N

31
Q

modified thorington phoria

A

uses thorington cards

  • D at 10ft
  • 40cm at near
32
Q

instructions for thorington phoria

A
  • same as maddox rod
  • cc
  • hold maddox rod over OD
  • ask where line is relative to the light
  • DLP by modified thorington: 4 prism D, DVP ortho
33
Q

normal findings with thorington phoria

A

D: 1 pD XP +/- 2 pD
N: 3pD XP +/- 3 pD

34
Q

3 possible reflexes in Hirschberg

A
  • center of pupil
  • nasal to the pupil (ex, positive lambda)
  • temporal to pupil (neg lambda, eso)
35
Q

what is normal corneal reflex in Hirschberg?

A

about 0.5mm nasal to the center of pupil