Entrance Tests Flashcards
What is the Hirschberg Test?
This is a rough objective estimate and measurement of a deviation/strabismus. Evaluating the visual axes OU under binocular conditions at near.
The Hirschberg test is especially useful for patients who are:
young and uncooperative
Should the Hirschberg test be done with glasses or without?
WITHOUT glasses
1st step of the Hirschberg test: A penlight is held straight in front of a patient’s face at about ____. The patient is instructed to fixate on the penlight with ____.
50 cm
both eyes open
2nd step of the Hirschberg test:
Occlude one eye at a time to observe the position of the corneal reflex.
3 possible corneal reflex positions:
Center of the pupil
Nasal to the pupil (positive angle lambda or kappa, exo posture)
Temporal to the pupil (negative angle lambda or kappa, eso posture)
In the Hirschberg test, what are the 3 possible corneal reflex positions?
3 possible corneal reflex positions: Center of the pupil Nasal to the pupil (positive angle lambda or kappa, exo posture) Temporal to the pupil (negative angle lambda or kappa, eso posture)
3rd step of the Hirschberg test:
Then occlude the other eye.
Now look at the corneal reflex in each eye.
The Hirschberg test indicates whether or not there is strabismus. How?
Now look at the corneal reflex in each eye. If the reflex are in the same relative position, compared to when the eyes occluded, there is no strabismus If the reflexes are not in the same relative position, there is strabismus. Determine the direction relative to angle lambda.
Hirschberg test: In the absence of strabismus, the corneal reflex should be _____ in both eyes.
centered
Hirschberg test: In the presence of strabismus, the reflex will not be in the center of the ______ eye and it will be different from the relative angle lambda in that eye.
deviated
Hirschberg test: For 1 mm of estimated deviation, it is approximately a deviation of _____ prism diopters
22
How do you record results of a Hirschberg test?
In recording, indicate that you did Hirschberg.
NO strabismus: record ortho or symmetrical
Strabismus present: record the deviated eye, the size and direction of the deviation.
Hirschberg: no strabismus or ortho
Hirschberg: 44pd LET; Krimsky 45pd LE
What is the Krimsky test?
Krimsky test: use prisms to determine the angle of deviation seen on Hirschberg test.
Krimsky:Prisms are placed in front of the ______ until the corneal reflexes are symmetrical.
fixating eye
Base Out prism is used for 1. _______
Base In prism is used for 2. _______
- esotropia
2. exotropia
In the Prism Reflection Test, the prism is held in front of the _______ until the corneal reflex is symmetrical.
deviated eye
What is the Near point of Convergence (NPC)?
This is to determine the ability to converge and maintain fusion.
NPC is done _______, good lighting and start at about _______.
with correction
40cm
NPC: Requires a penlight or transilluminator, red glass, near accommodative target (_____ letter).
a 20/30
Note: the transilluminator is used for the initial screening and if there is a receeded NPC, the red glass and then the accommodative target is used.
What are the first steps of the NPC?
- Instruct the patient to look at the light
- Ask the patient if it is single or double; if double, move the target away further back
- Move the target towards the patient while paying attention to the eyes.
NPC: Move it into the patient until the patient reports double or you see one eye loses fixation, take note of this distance (_________).
Now move the target back again until the patient reports single vision or where you notice refixation. Measure this distance (_______)
- break point
2. recovery
What is a normal finding of NPC?
Normal finding: Break 2.5cm/Recovery 5cm, or, to the nose (TTN) This should be the same with penlight, red glass and with an accommodative target!
If the NPC is abnormal:
Repeat with red glass over right eye (or Red Green glasses); then repeat a 3rd time with an accommodative target.
How do you record NPC results?
Record
• with or without correction
• the target used
• the distance (cm) where there was a break or diplopia (from bridge of nose or spectacle plane)
• distance of recovery
• the deviated eye and the direction
• diplopia or suppression (break without diplopia)
Example
• NPC cc light: TTN
• NPC sc light: 10cm/15cm, OD out, suppression
Red/Green: 15cm/20cm, OD out, suppression Accommodative: 12cm/16cm, OD out, suppression
Receeded NPC can cause
- Binocular vision problems
- Eyestrain/asthenopia
- Reading difficulties
- Difficulties with near point tasks
What is the Amplitude of Accommodation?
Measures a patient ability to accommodate (in diopters)
What do you need for the Amplitude of Accommodation test? Does the patient do it with or without correction?
Patient wears correction, near point accommodative target, occluder, illumination
Near Point Accommodation Push Up Method: Tell the patient to occlude one eye, tell patient to look at a row of letters (one or 2 lines better than BCVA at N)
Tell the patient to keep the letters clear. Slowly move the letters _______ to the patient, until the patient reports blur.
Measure the distance from the patient’s spectacle plane in _____. This is the near point of accommodation
To convert into diopter, divide 100 by the near point of accommodation and report the amplitude of accommodation in D
Occlude the other eye and repeat.
cm
closer
Near Point 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). The patient should report blur.
Slowly move the letters ________from the patient, until the patient reports clarity. Measure the distance from the patient’s spectacle plane in cm. This is the near point of accommodation
To convert into diopter, divide 100 by the near point of accommodation and report the amplitude of accommodation
Record the method use: Push up or Push away the amplitude of accommodation (D) for each eye
away
What is an example of accommodation recording?
e.g. Amp of accommodation: 9D OD, 10D OS
What are the expected results of the accommodation pull away and push away tests?
Expected:
Both eyes should be within 1D of each other Accommodation decreases with age.
Could also be affected by medications and diseases.
What are other methods to estimate the amplitude of accommodation?
Hofstetter’s formula
Donder’s Table
What is Hofstetter’s formula?
Minimum expected amplitude = 15 – 0.25 (age)
What are causes of abnormal accommodation?
- Accommodation decreases with age.
- It is also affected by medications (such as CNS simulants, tranquilizers, antihistamines, cycloplegics, antidepressants)
- Iridocyclitis
- Trauma causing iris tear.
- Alcohol
- Some glaucomas.
- Diabetes, Multiple sclerosis
What is binocular vision?
Binocular vision allows us to appreciate many aspects of a target. It has a sensory system and a motor system. If all these systems work well, they give one image from both retinal images and high resolution. There is little disparity.
Binocular vision gives advantage over monocular vision and monocular clues e.g, depth, more precise, quicker
What is binocular vision’s sensory system?
Sensory system: constructs single perception from 2 retinal images.
- Achieves single image from both eyes, gives the distance of the target.
What is binocular vision’s motor system?
Motor system: vergences and eye movements
- Coordinates the orientation of the eyes in all distances, and on your moving targets.
- Coordinates with the accommodative system to maintain a clear image.
Binocular vision’s motor system coordinates with the _________ system to maintain a clear image.
accommodative
Poor binocular vision leads to
Fatigue
Eye strain
Headaches
Binocular vision is in jeopardy in
Eye disease
Strabismus
Trauma
What is stereopsis?
An indicator of binocularity – the sensory and motor fusion of vision; also shows if accommodative and vergences systems are working well. An indicator of binocularity – the sensory and motor fusion of vision; also shows if accommodative and vergences systems are working well.
Purpose: this is to measure fine depth perception by evaluating the ability to fuse stereoscopic targets.
Stereopsis indicates if there is fusion or not. What is fusion?
Fusion is how the eyes unite!
There are three degrees of fusion. What are they?
There are 3 degrees of fusion:
- Simultaneous perception and superimposition (1st degree) NPC break
- Flat fusion (2nd degree) NPC recovery, 2 images into 1
- Stereopsis (3rd degree) to get stereopsis, binocularity has to be excellent to fuse fine disparity
What is the purpose of stereopsis?
Purpose: this is to measure fine depth perception by evaluating the ability to fuse stereoscopic targets.
What equipment is needed for stereopsis tests?
Equipment: polaroid glasses (or red-green glasses depending on the test) and the Stereo book
- there are a number of stereo books such as Random Dot 2, Titmus, Bernell, TNO Test, Random Dot E, PASS Test
In stereopsis, the patient wears the polaroid glasses over _______. Testing distance is 40cm with an overhead light, avoid glare.
near correction
Stereopsis:
- Direct the patient to page 2 with the smallest targets which are ______.
- Starting with the first box, ask the patient to identify which circle is “different of floating.” The “right, middle or left?”
- Ask the patient to identify the target in space - Repeat for all 12 boxes or until the patient misses 2 boxes in a row
- Record the level of stereopsis
(3 circles in 12 boxes)
If the patient does not appreciate stereo or is unresponsive, use the _________ and repeat the steps above.
If the patient identifies all the medium targets correctly, try the smaller targets again.
If a patient is not able to correctly identify any of the small or the medium targets, show the patient the largest targets.
medium size targets
What facts should be recorded in a stereopsis test?
Record Stereo at N and the test used
Indicate if it was done with or without correction
Stereopsis is recorded in “seconds of arc”
What is the measurement used for stereopsis?
arc second
Give sample recordings of stereopsis. What is a normal finding?
If the patient did not appreciate any stereopsis, write “no stereo.”
Expected stereo at near: 30 seconds of arc
Stereo at N cc: none, Random Dot 2
Stereo at N sc: 400 seconds of arc, Stereo E
To assess flat fusion at distance and near. Ability to detect a small central scotoma at near. What stereopsis test is this?
Worth 4 Dot
When is the Worth 4 Dot test used?
When stereopsis is below normal.
Should the Worth 4 Dot test be done with or without correction?
With correction.
What are the setup instructions for the Worth 4 Dot?
With correction, red-green glasses over correction, red lens over right eye. Worth 4 dot can be done at distance and near at 40 cm.
In the Worth 4 Dot test where are the red and white lights positioned?
Tell the patient to look at the W4D target with the red dot on top and the white on the bottom .
Worth 4 Dot:
Ask the patient how many dots they can see.
4 dots: _________
2 red dots: only the red (right) eye is used, OS (left) is _____
3 green dots: only OS (left) sees, OD is _____
5 dots: _____
- normal flat fusion
- suppression
- suppression
- diplopia
Worth 4 Dot: When testing for _______ at near, make sure there is normal flat fusion with worth 4 dot at near.
scotoma
Tell the patient to look at the flashlight and tell you if there is a change to 2 or 3 dots instead 4 dots.
Slowly move the flashlight away from the patient.
Stop when and if the patient says there is a change in the number of dots. If there is no change in the number of dots at 10ft, stop! No suppression
If there is a change, determine and record which eye is suppressed and at what distance.
Ask the patient to cover the dominate eye, ask if the suppressed dots reappear.
If they reappear, there is a suppression scotoma under binocular conditions. If they do not reappear, there is a unilateral scotoma.
Give a sample recording for Worth 4 Dot.
Record the distance
W4D: fusion at distance and near
W4D: fusion at distance, suppression OD at near
W4D: diplopia, eso with right hyper @ N.
Convergence tries to maintain binocular vision by ensuring images are on ___________of each eye so there is no disparity between the images
e.g. NPC is the closest distance where the eyes can converge and maintain binocular vision
corresponding retinal areas
A patient may appear aligned, but there could be underlining abnormalities in the ability to keep fusion.
Symptoms associated with a heterophoria could occur if fusional amplitudes are not enough.
Heterophoric abnormalities include:
Convergence insufficiency
Convergence excess
Divergence insufficency
Divergence excess
Phorias can be identified and measured during cover test, or with a ______ (in phoropter or in space).
Similar to cover test, _______ rod is used to measure horizontal and vertical phoria at distance and near.
The rod dissociates the eyes.
maddox rod
What equipment is needed for the Maddox rod phoria?
Maddox Rod Phoria (in space)
Need: Penlight, handheld maddox rod, prisms (bar or loose)
Is the Maddox rod test done with or without correction?
This is done with correction
Maddox Rod Instructions:
- Hold a penlight at 40cm for near testing
- Have the patient look at the muscle light for distance testing
- The patient holds the maddox rod over the right eye
- For horizontal phoria, the grooves on the maddox rod are oriented horizontally. The patient will see a 1._____streak.
- For vertical phoria, the grooves are oriented vertically, giving a 2.______ streak.
- Instruct the patient to look at the white light and also be aware of the red or white streak
- Ask the patient where the line is relative to the white light.
- vertical
2. horizontal
Maddox Rod:
Red line through the light: 1._____
- Red line to the right of the light: 2.______
- Red line to the left of the light: 3.______
- Red line below the light: 4.______
- Red line above the light: 5. ______
- ortho
- uncrossed diplopia (eso)
- crossed diplopia (exo)
- right hyper
- left hyper
What is suppression?
*Suppression is the active deactivation of a retinal image in one eye by the visual cortex.
The brain prefers to suppress and provide vision as close to binocular vision as possible instead of:
any image disparity blurred vision diplopia confusion
Suppression of an eye is a subconscious adaptation by a person’s brain to eliminate the symptoms of disorders of binocular vision such as strabismus, convergence insufficiency and aniseikonia.
What is alternate suppression?
A patient could also have alternate suppression (see 2 dots then 3 dots)
______ are used at distance and near. This can also be done in the phoropter or in space.
Thorington cards
Equipment: penlight, maddox rod, Thorington card.
On the distance card (distance is 1.____), the spacing on the card represents ___pd. On the near distance card (3. ___), the spacing also represents 1pd.
There is a hole in the cards, where a penlight is held.
- 10 ft
- 1 PD
- 40 cm
- 1 PD
