Lecture 6

Question 1

What are the two types of motor fusion?

Answer 1

1. Patient has no motor fusion (strabismus)

2. Patient has motor fusion but has trouble maintaining it (phoria)

Question 2

Alignment of the eyes depends on what two things?

Answer 2

1. tonic vergence

2. fusional vergence

Question 3

Define tonic vergence

Answer 3

muscle tone of the EOMs

Question 4

Define fusionsal vergence

Answer 4

eye movement that occurs in response to retinal disparity (or stimulation of non corresponding points)

Question 5

Define Proximal vergence

Answer 5

eye movement that occurs because an object appears close to the patient

Question 6

If a person has phoria do they have motor/sensory function? does someone with strabismus have then?

Answer 6

someone with phoria does (fusion just gets disrupted). someone with strabismus has no motor fusion and no sensory fusion (therefore has NO binocular vision).

Question 7

What is angle lambda or angle kappa? in which test can this be seen?

Answer 7

the angle between the pupillary axis and the line of sight.

hirschberg.

Question 8

If the hirschberg reflex is central what is the angle of lambda? reflex is nasal? reflex is temporal? which is the most common?

Answer 8

zero
positive (nasal is most common)
negative

Question 9

What does hirschberg test?

Answer 9

whether the patient has strabismus or not.

Question 10

Accommodative esotropia is found in which type of patients? what is it?

Answer 10

hyperopic patients (corrected with plus lenses), they are able to accommodate to see clearly by converging and becoming and esotrope.

Question 11

For every 1 mm away from the pupillary axis, how many prism diopters are needed for correction?

Answer 11

22

Question 12

Is we observe the hirschberg reflex and one is turned less than 1mm is this strabismic?

Answer 12

no, anything less than 1mm is normal.

Question 13

Can we restore binocular vision in someone who has never had it?

Answer 13

NO. because it takes place in the cortex and we cant change the cortex.

Question 14

Can someone with a phoria be identified in hirschberg or krimsky?

Answer 14

NO

Question 15

What does bruckner determine?

Answer 15

whether a patient has strabismus or not (brighter eye= the eye with the issue, darker eye= fixating eye).

Question 16

Why does the darker eye appear dark in bruckners? Why does the bright eye appear bright in bruckners?

Answer 16

dark eye due to the fact that the eye is lined up with the macula (using the fovea) therefore lots of pigment. the brighter eye is not lined up with the macula it is using non macular retina which is less pigmented.

Question 17

What is a bilateral cataract? what does it look like in bruckners?

Answer 17

cataracts in both eyes. looks equal in brightness in bruckners but the middle appears hazy.

Question 18

What is bruckners a reflection of?

Answer 18

back of the eye (fundus), shows blood vessels in choroid layer.

Question 19

Does the bruckners test work for everyone?

Answer 19

NO

Question 20

Does unequal brightness in either eye always mean strabismus in bruckners?

Answer 20

NO. it could mean difference in refractive error (anisometropia), media opacities, anisocoria.

Question 21

Bruckners test is inaccurate in what ages?

Answer 21

younger than 8 months.

Question 22

If a patient has hyperopia, what can be seen in the bruckners test to reassure this? what about for myopia?

Answer 22

Dark crescent down and or to the right in the red reflex.

dark crescent up and or to the left in red reflex.

Question 23

Cover/uncover test shows us what?

Answer 23

differentiates between phorias and tropias, tells us if a tropia is a constant R, constant L or alt.

Question 24

What does the alternating cover test tell us?

Answer 24

the direction and the size of the tropia or the phoria.

Question 25

In someone with a phoria, under normal conditions the eyes are aligned and patient is binocular but one eye turns when fusion is disrupted. What does the patient use to maintain binocularity?

Answer 25

fusional vergence.

Question 26

What target do you use for patient doing distance cover test?

Answer 26

one letter one line above normal VA in poor eye.

Question 27

What does herrings law state?

Answer 27

the angle between the eyes always stays the same.

Question 28

Strabismus has to be categorized by what two things?

Answer 28

unilateral (R or L) OR alternating

Constant (always there) OR intermittent

Question 29

R hyper is the same as what? L hyper?

Answer 29

L hypo

R hypo

Question 30

Which deviation is usually the biggest horizontal or vertical?

Answer 30

Horizontal (measure this first)

Question 31

how many prism do we use per eye?

Answer 31

JUST ONE. so if a patient has both a vertical and horizontal deviation, measure horizontal deviation first (bigger one) put the prism on either eye, then on the opposite eye put the vertical prism correction.

Question 32

“Cover” part differentiates between what? “uncover” part? alternating part?

Answer 32

phorias and tropias
alternating tropias and monocular tropias
direction of deviation

Question 33

What two distances is the cover test done?

Answer 33

distance (20 feet) and near (40 cm or 16 feet).

Question 34

when doing the distance cover test what is important to tell your patient?

Answer 34

keep the target CLEAR this reduces the chances of accommodation which could give the appearence of esotrope.

Question 35

What are normal cover test findings?

Answer 35

at distance: 1prism diopter exophoria (+/- 2prism diopters)

at near: 3prism diopters exophoria (+/-3prism diopters)

Question 36

What are the limits of tropias that start to be visible by casual observers?

Answer 36

greater than 9 prism diopters for exotropia and greater than 14.5 prism diopters for esotropia (beyond these numbers it is visible and could be a cosmetic problem).

Question 37

Which types of tropia can result in amblyopia? can phorias result in amblyopia?

Answer 37

constant R or L NOT alternating tropias. phorias do NOT result in amblyopia!

Question 38

What are three amblyopic conditions?

Answer 38

1. constant unilateral strabismus
2. amblyogenic refractive error
3. image degradation
   (condition must occur before the age of 6-8).

Question 39

tropias that occur after the age of 6-8 would they have amblyopia?

Answer 39

NO.