Binocular Vision Flashcards
Why test binocular vision?
if 2 eyes not working together efficiently=symptoms
What happens if only one eye is working?
strabismus or amblyopia, reduced acuity, no 3D, career considerations
Why do we do BV testing?
to determine if child is using both eyes (motor and sensory)
What are BV tests?
alignment, motilities, tests of motor fusion, tests of sensory fusion
What are tests of motor fusion?
NPC, vergences
What are tests of sensory fusion?
stereopsis, worth 4 dot
T/F infants are esotropic
false, may look esotropic because of lid anatomy but are not
T/F infants have poor control of convergence in the first few weeks of life
true
How many infants are orthophoric?
1/2
How many infants are exotropic/ C or I?
1/3
When should you expect orthophoria and convergence from an infant?
3 months
What is the purpose of a cover test?
to determine ocular alignment in different positions of gaze, frequency and magnitude
What are normal values for cover test?
distance: ortho- 3XP
near: ortho-6XP’
What does the unilateral cover test detect?
tropia
What does the alternate cover test detect?
phoria
What does the prism alternate cover test measure?
movement with prism
What prism neutralizes Eso, Exo, Hyper, Hypo?
BO, BI, BD, BU
Which distance is harder for infant cover test… distance or near?
distance, may only get near info
What should the target be for an infant cover test?
your finger
What is angle kappa?
angle between the line of sight (fixation to fovea) and the pupillary axis
What is the pupillary axis?
center of pupil, tangential to cornea
How do you measure angle kappa?
look at corneal light reflex monocularly with light at 50 cm and midline
What is a + angle kappa?
reflex nasal=fovea displaced temporally
What is a - angle kappa?
reflex temporal= fovea displaced nasally
Most people have a mild ____ kappa
positive, fovea five degrees temporal to center of posterior pole
What is the hirschberg test?
looking at corneal reflex binocularly to determine if a deviation exists, estimates angle kappa
How do you do the hirschberg test?
light at 50 cm midline, reflex should be symmetrical OD, OS and roughly 0.5 mm nasal
What is 1mm in prism diopters?
22 prism diopters
Displacement nasal (+)=
exo
Displacement temporal (-)=
eso
What is the Krimsky test?
essentially hirschberg with prism, still observing corneal reflex with light at 50 cm midline
What is fixating v nonfixating eye in krimsky?
check for differences and not modified/reverse krimsky for non-fixating eye ????
What is the bruckner test?
using direct ophthalmoscope, adjust focus so patient’s face is clear, 1 m in front of paitent
What do you look at with bruckner test?
hirschberg (check for strabismus) and size/color of pupils and brightness of fundus reflex
Which eye is brighter in a bruckner test?
strabismic, because of the macular pigment
What can the size, color and brightness of the pupil tell you?
strabismus, anisometropia, media opacities
T/F preschool and school aged kids should be able to get a cover test and distance and near
true
What do you have to record with strabismus?
test used, which eye, frequency, direction, distance/near?
How do you record the frequency of a strabismus turn?
POTT= percentage of time troped, constant or intermittent, exotropia scale
How long do you observe before testing and using the exotropia scale?
30 seconds
What is the procedure to use before looking at the exotropia scale?
cover OD 10 sec, cover OS 10 sec, cover OD 10 sec, distance and near
What numbers on the exotropia scale depict poor control?
3-5
Which numbers on the exotropia scale depict good control?
0-2
What is a 5 on the exotropia scale?
constant exotropia
What is a 4 on the exotropia scale?
exotropia > 50% of exam before dissociation
What is a 3 on the exotropia scale?
exotropia <50% of exam before dissociation
What is a 2 on the exotropia scale?
no exotropia unless dissociated, recovers in > 5 sec
What is a 1 on the exotropia scale?
no exotropia unless dissociated, recovers in 1-5 seconds
What is a 0 on the exotropia scale?
no exotropia unless dissociated, recovers in <1 second (phoria)
