Lecture Four

Question 1

define functional vision

Answer 1

ability to focus and coordinate the two eyes comfortably for visual tasks especially at near.

Question 2

failure to treat binocular abnormalties could result in?

Answer 2

amblyopia

Question 3

is amblyopia preventable? what percent of children have it in US?

Answer 3

yes

1-4%

Question 4

Define binocular

Answer 4

the use of both eyes simultaneously such that each retinal image contributes to the final perception

Question 5

what are the two categories of binocular problems?

Answer 5

1. binocular vision is maintained but is stressful and uncomfortable ( called phoria)
2. Binocular vision is absent (strabismus)

Question 6

What are two types of fusion?

Answer 6

1. sensory: ability to combine sensory information for each eye into a single image
2. Motor fusion: ability to align both eyes and maintain alignment.
   one cant happen without the other.

Question 7

what are some tests that can test for sensory fusion?

Answer 7

worth 4 dot and stereopsis

Question 8

what are some tests that can test for motor fusion?

Answer 8

hirschberg, bruckners, cover test and krimsky

Question 9

Does motor and sensory fusion occur separately or simultaneously?

Answer 9

simultaneously but tested separately.

Question 10

Reasons why we are binocular?

Answer 10

1. spare eye
2. larger field of view
3. defects in on eye often masked by the normal eye
4. some perceptions are better with two eyes i.e. VA
5. MAJOR REASON= stereopsis

Question 11

what is stereopsis?

Answer 11

perception of depth

Question 12

What two types of stereopsis do we use?

Answer 12

monocular and binocular cues. monocular used for far away things, binocular used more for up close.

Question 13

What are the three prerequistes needed for binocularity?

Answer 13

1. two eyes that function normally and equally
2. retinal image to OD and OS must be the same size, illuminance, location in space and color (sensory fusion)
3. the eyes must be capable of aligning so that retinal images of a fixated object can be placed and maintained on the fovea of each eye (motor fusion)

Question 14

what does a functional entrance binocularity test tell us?

Answer 14

if the patient has normal sensory and motor fusion. if not which prereq is missing

Question 15

What is a local sign?

Answer 15

tells us where things are located in space relative to one another and ourselves. It is innate and is a cortical process.

Question 16

Objects located in nasal space will be reflected on which retina (for right eye)? temporal space? when eye is looking straight ahead what part of retina is this focused on?

Answer 16

temporal retina.
nasal retina
fovea (in normal eyes).

Question 17

What are corresponding points?

Answer 17

pairs of points (one being in each eye) that have the same visual direction and sned their nerve impulses to the same point in the same visual cortex and give rise to sensory fusion.

Question 18

Objects imaged on corresponding points are seen what if patient has normal sensory fusion?

Answer 18

binocularly.

Question 19

What cortex does the fovea go to in each eye?

Answer 19

both cortexes at the same time

Question 20

Example of a corresponding point?

Answer 20

nasal point in right eye, temporal point in left eye, both going to the same cortex.

Question 21

what is a non corresponding point?

Answer 21

a point in one eye with another point in the other eye that are not going to the same cortex.

Question 22

What happens when we get stimulation of non corresponding points? what do small amounts lead to?

Answer 22

large amounts of retinal disparity which can lead to diplopia.
small amounts of retinal disparity lead to stereopsis

Question 23

What is physiological diplopia? how does it happen?

Answer 23

normal diplopia, occurs in patients with binocular vision.

happens by looking at two non fixated objects who images are stimulated on non corresponding points.

Question 24

What are the four types of sensory fusion?

Answer 24

1. Simultaneous perception (seeing an image with each eye at the same time i.e. dog and pig)
2. Superimposition (1st degree fusion): seeing two images and localizing them in the same place i.e. face in window
3. Flat fusion (2nd degree): combining two images with some similar detail and some non similar detail i.e. worth 4 dot
4. Stereopsis (3rd degre fusion): perception of depth, patient combines two images into a single one that has depth.

Question 25

Worth four dot: Red lens goes on which eye? green lens? testing distance? white dot orientated where? ask patient what? what is the normal response?

Answer 25

Right eye, left eye, 40cm, white dot on bottom. how many dots do you see? normal response is 4.

Question 26

if patient says they see 5 dots in worth 4 dot, what do you ask?

Answer 26

where are the two red dots? where are the 3 green dots? ( eyes are not aligned)

Question 27

if patient sees just two red dots what is happening?

Answer 27

suppression of OS

Question 28

if patient sees just 3 green dots what is happening?

Answer 28

suppression of OD

Question 29

If red dots are to the right and green are to the left what do we have? if red dots are to the left and green dots are to the right?

Answer 29

``` uncrossed diplopia (eso, one eye turned in) crossed diplopia (exo, eye turned out) ```

Question 30

if red dots are up and green dots are down? if red dots are down and green dots are up?

Answer 30

``` left hyper (OS higher than OD) right hyper (OD higher than OS). ```

Question 31

Normal recording for worth 4 dot?

Answer 31

worth 4 dot @40cm fusion

Question 32

What is always associated with vertical deviation?

Answer 32

a direction, right or left.

Question 33

Some people will see 4 dots but there eyes are clearly not aligned (determined in externals) why?

Answer 33

sensory adaptation, NOT sensory fusion. called anomalous retinal correspondence.

Question 34

Uncrossed diplopia gives what kind of eye turn?

Answer 34

esotropia

Question 35

Crossed diplopia gives what kind of eye turn?

Answer 35

Exotropia

Question 36

If red are up and green are down?

Answer 36

Left hyper (OS higher than OD)

Question 37

If green are up and red are down?

Answer 37

Right hyper (OD higher than OS)

Question 38

Left hyper is the same as?

Answer 38

right hypo.

Question 39

how many responses are possible on worth 4 dot?

Answer 39

7

Question 40

Who sees 5 dots in the worth 4 dot test?

Answer 40

1. strabismus: misalinged eyes (most people with strabismus will not see 5 dots they will suppress one eye i.e. 2 red dots or 3 green dots) 2. phoria: patients who have normal fusion under normal circumstances but cant maintain fusion when wearing glasses.

Question 41

When we detect an anisocoria, what has to be determined?

Answer 41

whether it is physiological or acquired (pathological)

Question 42

What are some crucial things to check to see if anisocoria is physiological?

Answer 42

1. has been there for a while, previous photos 2. no ptosis 3. no EOM abnormalties 4. Normal responses to light (D&C) 5. Asymmetry the difference between the pupil sizes should be the same in dim and bright light.

Question 43

what percent of people have an anisocoria? what is the normal difference in size?

Answer 43

20% | greater than or equal to 0.4mm

Question 44

If anioscoria is pathological what must be determined?

Answer 44

which pupil is abnormal

Question 45

If the difference between pupil sizes is bigger in bright light than that in dim light which eye is the bad one?This is due to what type of an effect? if there were ptosis or EOm abnormalties in this condition what could this mean?

Answer 45

one with large pupil. parasympathetic efferent pathway defect. damage probably closer to ciliary ganglion.

Question 46

If the difference between pupil sizes is bigger in dim light than that in bright light which eye is the bad one? this is due to what type of defect?

Answer 46

one with the smaller pupil. | sympathetic pathway defect: dilation lag.

Question 47

two examples of diseases that can occur when we have the difference in pupil sizes bigger in bright light than in dim light?

Answer 47

1. Adies Tonic Pupil: most common, in younger aged women usualy 20-40, no ptosis, no EOM abnormalties. 2. CN3 palsy: abnormal EOMS, ptosis occurs in the eye with the larger pupil, pupil end up facing down and out. if pupil doesnt function normally this is another type of CN3 palsy where it could be an angorism (usually patient has a headache, GO TO EMERGE).

Question 48

Example of a disease of anisocoria when the difference in pupil size is greater in dim light than bright light?

Answer 48

Horner's syndrome: miosis, mild ptosis in the eye that has the smaller pupil.

Question 49

Does a +RAPD cause anioscoria?

Answer 49

NO

Question 50

What two muscles does CN3 innervate in the inferior division?

Answer 50

ciliary body (accommodation) and iris sphincter muscle.

Question 51

What nerve affects pupils, EOMs and accommodation?

Answer 51

CN3

Question 52

Superior division of CN3 affects what muscles?

Answer 52

SO and levator palpebral superioris.

Question 53

In CN3 palsy which muscles work?

Answer 53

only SO and LM (because they are not innervated by this nerve) therefore only up and down works.

Question 54

What is duction?

Answer 54

movement of one eye along one axis. horizontal: supraduction (up), infraduction (down). Vertical axis: abduction (out) or adduction (in).

Question 55

What are vergences? 2 types are?

Answer 55

movement of both eyes in opposite directions. convergence: both eyes moving in divergence: both eyes move out

Question 56

What is version movement? examples?

Answer 56

movement of both eyes by same distance and in same direction. dextroversion: both eyes looking to the right levoversion: both eyes looking to left supraversion: both eyes looking up infraversion: both eyes looking down

Question 57

If strabismus is found in a patient what must be determined?

Answer 57

whether it is comitant or non comitant. | comitant: the eye turn is the same in all positions of gaze, can be determined by hirschberg during EOM movements (5PD)

Question 58

what is hypertropia?

Answer 58

one eye deviated upwards.