Entrance Tests Flashcards
____ contructs single perception from 2 retinal images
Sensory system
_____ system achieves a single image from both eyes; gives the distance of the target
Sensory
Poor binocular vision leads to
fatigue
eye strain
headaches
Binocular VA is in jeopardy in
Eye disease
Strabismus
Trauma
Name the 3 degrees of fusion:
- Simultaneous perception and superimposition (1st degree)
- Flat fusion (2nd degree)
- Stereopsis (3rd degree)
In order to get ____, binocularity has to be excellent to fuse fine disparity
stereopsis
The purpose of ____ is to measure fine depth perception by evaluating the ability to fuse stereoscopic targets
Stereopsis
We use the Worth 4 Dot when
stereopsis is below normal
Worth 4 Dot is used to
assess flat fusion at distance and near. Allows for the ability to detect a small central scotoma at near.
When testing for scotoma at near, make sure there is ____ with worth 4 dot at near.
normal flat fusion
Rough objective estimate and measurement of a deviation/strabismus. Evaluating the visual axes OU under binoc conditions at near.
(Just looking at the reflex)
Useful in young and cooperative patients.
Hirschberg Test
For this test, a penlight is held straight in front of a patient’s face at about 50 cm.
The patient is instructed to fixate on the penlight with both eyes open.
Hirschberg Test
3 possible corneal reflex positions for Hirschberg Test:
- Center of pupil
- Nasal to the pupil
- Temporal to the pupil
Hirschberg Test:
In the absense of a strabismus,
the corneal reflex should be centered in both eyes
Hirschberg Test:
In the presence of a strabismus,
the reflex will not be in the center of the deviated eye and it will be different from the relative angle lambda in that eye.
Hirschberg Test:
For 1 mm of estimated deviation, it is approximately a deviation of ____
22 prism diopters
When do you use Krimsky Test?
When you determine a deviation within the Hirschberg Test
This test is when you use prisms to determine the angle of deviation on Hirschberg Test.
Krimsky Test
For the Krimsky Test, prisms are placed in front of the ____ eye until the corneal reflexes are symmetrical.
fixating
Krimsky Test:
Base Out prism is used for _____
esotropia
Krimsky Test:
Base In prism is used for _____
exotropia
The Near Point Convergence (NPC) is to determine the
ability to converge and maintain fusion.
Near Point Convergence (NPC) test:
1) . Instruct the patient to look at the light
2) . Ask the patient if it is single or double; if double, move the target away further back
3) . Move the target towards the patient while paying attention to the eyes.
4) . Move it into the patient until the patient reports double or you see one eye loses fixation, take note of this distance (break point).
5) . Now move the target back again until the patient reports single vision or where you notice refixation. Measure this distance (recovery).
What all do you have to record for NPC?
1) . with/without correction
2) . the target used
3) . the distance (cm) where there was a break or diplopia (from bridge of nose or spectacle plane)
4) . distance of recovery
5) . deviated eye and the direction
6) . diplopia or suppression (break without diplopia)
Receeded NPC can cause:
- Binocular vision problems
- Eyestrain/asthenopia
- Reading difficulties
- Difficulties with near point tasks
______:
Measures a patient’s ability to accommodate (in Diopters)
Patient wears correction
Equiptment:
Near Point Accommodative Target
Occluder
Illumination
Amplitude of Accommodation
What two methods are used to test the Amplitude of Accommodation?
Push Up Method
Pull Away Method
Amplitude of Accommodation:
Push Up Method:
- Tell the patient to occlude 1 eye
- Tell patient to look at a letter or a row of letters (one or two lines better than BCVA at N)
- Tell the patient to keep the letters clear.
- Slowly move the letters closer to the patient, until the patient reports blur.
- Measure the distance from the patient’s spectacle plane in cm.
- Occlude the other eye and repeat
Amplitude of Accommodation:
Pull Away Method:
- Occlude one eye, tell patient to look at the row of letters
- Tell the patient to keep the letters clear
- Hold the letters/target very close to the patient’s open eye (about 0.5cm). This patient should report blur.
- Slowly move letters away from the patient, until the patient reports clarity.
- Measure the distance from the patient’s spectacle plane in cm.
Which methods can be used to estimate the Amplitude of Accommodation?
Hofstetter’s formula
Donder’s Table
What is Hofstetter’s formula?
Minimum expected amplitude = 15 - 0.25(age)
Accommodation ____ with age
decreases
_____ is affected by medications.
Give examples
Accommodation
CNS stimulants, tranquilizers, antihistamines, cycloplegics, antidepressants
Name all the ways that accommodation can be affected
alcohol age medications iridocyclitis trauma resulting iris tear alcohol some glaucomas diabetes, multiple sclerosis
_____ allows us to appreciate many aspects of a target.
Binocular VA
Sensory system:
constructs single perception from 2 retinal images
Motor System:
Vergences and Eye Movements
_____ achieves single image from both eyes, gives the distance of the target
Sensory System
____ coordinates the orientation of the eyes in all distances, and on your moving targets.
Motor System
_____ coordinates with the accommodative system to maintain a clear image
Motor System
Poor Binocular VA leads to
Fatigue
Eye Strain
Headaches
Binocular VA is in jeopardy in
Eye disease
Strabismus
Trauma
3 degrees of Binocular VA
1) . Simultaneous perception and superimposition (1st degree) (NPC Break)
2) . Flat fusion (2nd degree) (NPC recovery, 2 images into one)
3) . Stereopsis (3rd degree)
If all of these systems work well _____ resulting in ____
they give one image from both retinal images and high resolution.
(resulting in) little disparity
Why is binocular VA give an advantage over monocular VA?
- depth
- more precise
- quicker (response)
____ is an indicator of binocularity– the sensory and motor fusion of VA; also shows if accommodative and vergences systems are working well
Stereopsis
For stereopsis, you are seeing if the two eyes
are able to perceive information about the image, the depth, its distance, etc
To get stereopsis, binocularity
has to be excellent in order to fuse fine disparity
The purpose of _____ is to measure fine depth perception by evaluating the ability to fuse stereoscopic targets.
stereopsis
The testing distance for Stereopsis is ____
40 cm
What equipment do you use for stereopsis?
Polaroid glasses (or red-green glasses depending on the test), overhead light and the Stereo book
Name a few of the stereo books that are commonly used
Random Dot 2 Titmus Bernell TNO Test Random Dot E PASS Test
When do you stop when doing a stereopsis test?
When the patient has missed 2 or more (in a row?)
Do you test stereopsis with correction (cc) or without correction (sc)?
With correction (cc); the patient should wear the polaroid glasses over their near correction
When testing adults for stereopsis,
1). Direct the patient to page 2 with the smallest targets (3 circles in 12 boxes)
2). Start with the first box, ask the patient to identify which circle is “different of floating”
The “right, middle, left?”
3) . Ask the patient to identify the target in space
4) . Repeat for all 12 boxes or until the patient misses two boxes in a row
5) . Record the level of stereopsis
If the patient does not appreciate stereo or is unresponsive,
use the medium size targets and repeat the steps above.
If the patient identifies all of the medium targets correctly,
try to the smaller targets again.
If the patient is not able to correctly identify any of the small or medium sized targets,
show the patient the largest targets
Stereopsis is recorded in
“seconds of arc”
If the patient did not appreciate any stereopsis, record ____
“no stereo”
Expected stereo at near:
30 seconds of arc
____ is to assess flat fusion at distance and near. The ability to detect a small central scotoma at near
Worth 4 Dot
When do you test Worth 4 Dot?
When stereopsis is below normal
Worth 4 Dot test:
1) . Tell the patient to look at the W4D target with the red dot on top
2) . Ask the patient how many dots they can see
3) . With 5 dots, ask where the red or green dots are located. This determines the location of this visual axes.
W4D: 4 dots: 2 red dots: 3 green dots: 5 dots:
4 dots: normal flat fusion
2 red dots: only the red eye, OS is suppression
3 green dots: only OS sees, OD is suppression
5 dots: diplopia
Is it possible to perceive vertical diplopia? When does this happen?
Yes, if the red dots are below the green dots, there is a right hyper deviation.
