Lecture 11 Functional Entrance Tests part 2

motor fusion

controlled eye movements to fuse an image

sensory fusion

neurophysical; visual cortex combines superimposed views obtained independently by the two

what does motor fusion test determine

ability to align and maintain alignment with a given visual target

what does sensory fusion test determine

ability to combine visual information from each eye into a single precept (perception)

aside from the Hirschberg test, what is another motor fusion test

near point of convergence

aside from W4D, what is another sensory fusion test

stereopsis test

convergence

eyes move in

divergence

eyes moves out

hypervergence

one eye moves up relative to the other eye

hypovergence

one eye moves down relative to the other eye

purpose of near point convergence

to assess the absolute convergence limit of the patient’s eyes

is NPC objective or subjective

both objective and subjective

what is NPC important for diagnosing

convergence insufficiency (CI)

when do we always test for NPC

pediatric vision screening

what is convergence insufficiency (CI

binocular vision disorder characterized by poor convergence making it difficult to maintain binocular fusion at near

symptoms of CI

difficulty with/avoidance of near work, diplopia, headaches, asthenopia (eyestrain) and others

what kind of target can we use for NPC

accommodative or light with transilluminator

why is using an accommodative target better than a light target

because we are not accommodating as much with the light target and have to rely on vergence ability

what is the purpose of red lens (RL) and red green glasses (RG) in NPC

to increase difficulty because we are dissociating their eyes

for NPC, where do we move the target towards

the bridge of the patient’s nose

when do we stop moving the target with NPC

when patient reports double or when we observe one eye losing fixation

what is the break point of NPC

when one eye losing fixation

how do we obtain the recovery point in NPC

when the eye regains fixation or single vision after overshooting

when do we use the red lens for NPC

when patient is suspected to have CI

why do we use the red lens for patient with suspected CI

they might have regular findings with the accommodation or light target but receded results with red lens

when we introduce the red lens in NPC, what test is it becoming now

biocular test

when we do record suppression for NPC

when patient lost binocular fixation (break) but did not report diplopia

for accommodative target in NPC, what is the norms for break and recovery

<=5cm, <=7cm

for light target in NPC, what is the norms for break and recovery

<=7cm, <=10cm

why is the norms for break and recovery with light target larger than accommodative target

because the patient is not engaging with the accommodative system as much

with the red green glasses for NPC, what is the norms for break and recovery

<=5cm, <=7cm

three components of the synkinetic triad (near triad)

miosis, convergence, and accommodation

define miosis in the synkinetic triad (near triad)

pupils constrict

define convergence in the synkinetic triad (near triad)

eyes move inward

define accommodation in the synkinetic triad (near triad)

eyes increase focus and lens give us more plus power

when the patient looks at a near target, accommodation and convergence __ and pupils __

increases, constrict

what happens when the patient is looking at a distance target

divergence, accommodation relaxes, and pupils dilates

when patient reports double in NPC, is that a subjective or objective observation

subjective

when patient loses fixation in NPC, is that a subjective or objective observation

objective

if the patient reports diplopia but we do not observe either eye lose fixation, what should we record

the breakpoint where patient notices diplopia but make note that loss of fixation was not observed

what concept does the NPC test for

absolute convergence limit

receded NPC is a suggestion of what condition

convergence insufficiency

If a patient is symptomatic at near but has a normal NPC initially, what should we do

Repeat NPC with the red lens target

what is stereopsis

true binocular of depth (3D space)

for stereopsis, there are two images with retinal disparity. what does that mean?

similar images fall on non-corresponding points

separate but dissimilar images can be presented to each eye using what methods

polaroid filters, colour filters, synoptophore, stereoscope

when do we use monocular cues to depth

for perception of depth at far distances (>200 meters)

who uses monocular cues to depth?

patients with one functioning eye (“monocular”)

how do we obtain normal stereopsis?

both eyes must function normally and equally

what is the sensory fusion requirement for normal stereopsis?

similar retinal images in both eyes (form, size, illuminance and color)

what is the motor fusion requirement for normal stereopsis?

ability to align the eyes so that the retinal images are placed on the fovea

what is the gold standard for stereo

global stereopsis using random dot stereopsis

name the features of the local/contour stereopsis

 Two horizontally disparate stimuli each seen monocularly

Uses peripheral retinal point

name the features of global stereopsis/random dot stereopsis

Corresponding points and disparate points over a large binocular area

Perception of 3-D image requires binocular fusion

which stereo test do we use to detect amblyopia

global stereo

purpose of random dot 3 stereo testing

it is a subjective measurement of stereopsis and magnitude of fine depth perception

what are the suspected conditions that lead us to use random dot 3?

microtropia and intermittent strabismus

in random dot 3, if a patient provides an incorrect answer and misses the preceding circle target, what do we record

record the level of stereopsis associated with last correct target

in random dot 3, if a patient provides an incorrect answer and got the preceding circle target correct, what do we record

record that preceding target as the endpoint

smaller angular separation means

smaller sec of arc and finer retinal disparity

larger angular separation means

larger sec of arc and greater retinal disparity

when we change the testing distance in stereo, what are we also changing

the angualr separation

for closer distance with stereo, what happens to the angular separation

more angular separation —> grosser levels of stereo —> easier test

for further distance with stereo, what happens to the angular separation

smaller angular separation —> finer levels of stereo —> harder test

for smaller angular separation, are we overestimating or underestimating findings

underestimate

for larger angular separation, are we overestimating or underestimating findings

overestimate

stereopsis norms for adults with random dot 3

<= 40 sec arc

at what age would we get 40 sec of arc with children

5-8

purpose of Bruckner test

assess and screen for asymmetry of refractive error, media opacities, anomalies of the posterior pole, and strabismus

what does the Bruckner test evaluate

the equality of the retinal reflections of both eyes

is the Bruckner test objective or subjective

objective

when do we always do the Bruckner test

Routine examination of infants and young children of 6-7 years old

if we are looking at a target at 1m in the Bruckner test, what lens do we use

+1.00 D lens

if we are looking at a distance target at 4m in the Bruckner test, what lens do we use

+0.25 D lens

why should we use a 1m distance for the Bruckner test

because it is more sensitive to detection of strabismus, media opacities and retinal abnormalities

why should we use a 4m distance for the Bruckner test

because it is more sensitive to detect ametropia and anisometropia

what is anisometropia

Asymmetric refractive error(s) between the two eyes

what is ametropia

refractive error, which is the inability to focus images on the retina with the eye alone

what are the types of ametropia

myopia, hypermetropia, astigmatism, or presbyopia

what does equally bright (red or yellow) indicate in Bruckner reflexes

refractive errors are relatively equal with no strabismus or media opacities

what does equally dim indicate in Bruckner reflexes

bilateral high refractive error

what does unequal reflexes dim indicate in Bruckner reflexes

there is an anomalous eye which can be darker/duller, brighter white, or showing asymmetric shadowing/blockage

what does a darker/duller reflex in the Bruckner test indicate

anisometropia (duller is affected), meaning one eye has a higher refractive error

what does a bright white reflex in the Bruckner test indicate

strabismus or posterior pole abnormality (brighter is affected)

what does asymmetric shadowing/blockage in the Bruckner test indicate

media opacity

when testing for ametropia with Bruckner reflexes, what does a full bright red flex mean?

emmetropia

when testing for ametropia with Bruckner reflexes, what does white crescent on the bottom mean

myopia

when testing for ametropia with Bruckner reflexes, what does white crescent on top mean

hyperopia

when testing for ametropia with Bruckner reflexes, what does a white crescent slanted or tilted mean

astigmatism

what is considered a very large refractive error with the Bruckner test for ametropia

>4D

what is Retinoblastoma

a Rare, pediatric, retinal tumor that may present as leukocoria (whitening of the pupil)

what is leukocoria

whitening of the pupil

for using red lens in NPC, what is the norms for break and recovery

no norms yet