binocular video Flashcards
Motor fusion
The movement of the two eyes when retinal disparity is detected
Sensory fusion
Combinbin of two images in the visual cortex
What must happen for an object to be perceived as single
- Must fall on same retinal points 2. be clear 3. be similar size
Primary visual direction
The line of sight going through the foveal.
secondary visual direction
Lines of sight through all other retinal points.
Horopter
spatial representation of all points in space that are imaged on corresponding retinal points. Anything that falls on here will be seen as single
Panuo’s fusional space
an area immediately around the horopter where objects are still seen as single and in depth. This is where depth occurs
What VA to use with binocular vision testing
20/30 or two lines above there BCVA
Unilateral cover test
Allows the determination of a tropia vs. phoria.
ACT
Determines amount.
Expected phoria at distance
0-2 XP
Expected phoria at near
0-6 XP
Phi phenomeneon
With with XP. Against with EP.
what will you see with rod over L and hyper
Will see line below the light.
What will you see with rod over L and hypo
Will see line above the light
Exo on maddox rod
crossed
Eso on maddox rod
Uncrossed
Fixation disparity
small misalignment of the visual axes that is not observed as object falls in panuo’s fusional area. Measured under associated conditions.
Which AC/A will be greater?
The calculated due to proximal convergence.
What indirectly tests PRV
NRA
Which indirectly tests NRV
PRA
Blur point with fusional mergence testing
This is the limited of fusional mergence. Now they start using accommodative vergence
Break point
The limit of fusional and accommodative vergence
How big should the recovery be?
At least half the break.
What flipper to use with mergence facility
12 BO/3 BI.
What is normal mergence facility
15 CPM
How does the minus lens method differ from push up values
Minus lens will be 2 D less due to minifciation.
What values to test with accommodative facility
+/- 2.
Normal values for accommodative facility
8 cpm binocular or 11 cpm monocular
CI signs
large XP at near, low AC/A, receded NPC, reduced PFV, and a low lag, low NRP and trouble clearing plus lenses.
Pseudo CI
accommodative insufficiency leads to decreased convergence. Will have a decreased amplitude of accommodation, a low PRA, and will respond well to low plus at near.
What dx if patients presents will sudden symptoms of CI
MS and MG.
DI
Least common. Greater esophoria at distance, low AC/A, receded NFV at distance.
Convergence excess
Greater symptoms that CI. Reduced NFV ranges, higher AC/A and large lags. Will have a low PRA and inability to clear minus binocularity.
DE
Greater eco at distance than near. Can be more pronounced at near. High AC/A. PVF ranges at distance and near are usually normal? The patient may have a V pattern.
Basic XP
Normal Ac/A, reduced PFV, low NRA, low lag or lead, inability to fuse with Bo and clear plus
Basic EP
Normal AC/A, Reduced NRV, big lag, inability to fuse BI, hard to clear minus.
Vertical phobias.
Vertical phobias can be constricted if recent onset vertical deviation or larger than normal if the vertical deviation is longstanding.
Fusional Vergence Dysfunction
Normal phoria at distance and near, normal AC/A, normal accommodative function, and reduced PFV and NFV ranges at distance and near.
AI
high lag, inability to clear minus, reduced PRA, reduced amplitude of accommodation.
Accommodative Excess
Intermittent distance blur after near activities, difficulty shifting focus, normal to high AoA, reduced NRA, low lag or lead. Inability to clear plus.
AE vs Acom. spasm
Plus lenses will help with Acomm. spasm but not AE
AI
Reduced NRA and PRA and difficulty clearing plus and minus lenses on binocular and monocular accommodative facility testing.
Amblyopia definition
20/30 or worse or difference of 2 lines of visual acuity
When will amblyopia develop
From birth to 7-9.
Sensitive period
2-3 years old.
Suppression
When the image of one eye is filtered out at the level of the visual cortex
Diplopia
when an object falls on non-corresponding retinal points.
Confusion
Occurs when each macula views a different object.
Eccentric Fixation
Occurs when a non-foveal point is used for fixation in the strabismic eye. It occurs under monocular and binocular conditions. On CT the subjective deviation will be less than objective as patient will fixate with the eccentric fixation point.
Anomalous Retinal Correspondence
Can develop if foveal misalignment occur before the age of 5.
ARC vs. EF
ARC will only occur under binocular conditions. Under monocular conditions the deviated eye will use the fovea.
Angle of anomaly
Difference between objective and subjective deviaion
Harmonious ARC
The angle of anomaly equals the objective angle of deviation. The patient has no symptoms of diplopia and confusion. S=0.
Unharmonious ARC
The angle of anomaly is less than the objective angle of deviation. Subjective angle is not 0. Patient will have diplopia and confusion.
when does unharmonious ARC typically occur
2-3 weeks after strap surgery as transitions to HAC
Paradoxical ARC
When the fn moves in the direction opposite to the deviation. Patients will have worse diplopia and confusion.
Covariance
The type of correspondence shifts depending on which eye is fixating. Normal HAC when the normal eye fixating and NRC when the strabismic eye fixating.
Hirschberg
Nasal=XP temporal=EP.
Angle lambda
Monocular conditions and typically 0.5 mm nasal.
How much does a 1mm shift on hirshberg indicate
22 p.d.
Krimsky Test
Measures the magnitude of deviation using prism. The patient views a light source at 50 cm. Use prism to align using the norm BONES and BINX.
Bruckner test
80-100 cm away. Looking for equal reflex. The brighter eye will be deviating.
4 BO test
Detect a micro strabismus. Put 4 Bo in front of an eye. Normal is out and then in. If prism over OD: If OS makes an outward movement but not in->it is suppressing. If no movement: OD is suppressing.
Microstrabimus
deviation less than 10 that is not detected on any other tests of misalignment
How can patient get normal on after image test
IF NRC or if EF and Fe is in the same location as ARC under binocular conditions.
What does it mean if the vertical line is seen to the left when flashed vertical on right eye
OD esotropia with nasal fn relative to the fovea
what does it mean if the vertical line is seen to the right when flashed vertical on the right eye
OD exotropia with temporal fn relative to the fovea.
What is the major idea with after image test
Crossed=eso. Uncrossed=exo
What does right eye see with Bagolini lenses
/ Tilted to the Right
What does left eye see with bagolini lenses
\ Tilted to the left.
What if you see an X with Bagolini lenses
NRC if CT shows no tropia or Harmonious ARC if movement on CT is seen.
What if you see V on cover test
Esotropia with NRC or unharmonious unharmonious RC
What if you see ^ on cover test
Exotropia with NRC or unharmouns RC
First degree of fusion
superimposition targets. Cannot fuse together because they are different. Use for training
2nd degree of fusion
Flat fusion. Use targets with suppression cues. Patient do not have diplopia but no stereo
3rd degree of fusion
Stereopsis.
What does Worth 4 dot detect
flat fusion.
When to use worth 4 dot
When under 40 seconds of arc
What does the right eye see in worth 4 dot
2 vertical red dots.
What does the left eye seen in worth 4 dot
3 green dots.
When does a patient have deep suppression
if worth 4 dot doesn’t see fusion with lights dim and at near.
Local (contour) stereopsis
Uses monocular cues. Tests peripheral stereopsis.
Global (stereo) steropsis
Uses random dot targets with no local targets.
Expected stereo tests
20 seconds of arc with contour testing.
Horro fusionis
When a patient with heterotropia are unable to obtain fusion even with the use of prism.
Infantile ET
Congenital ET. A large angle constant ET that occurs prior to 6 months of age and is usually idiopathic in nature.
What conditions are infantile ET associated with
Overacting Inferior Oblique (hyper when adducting), DVD, latent nystagmus
Acquired ET
Occurs after 6 months of age. Can be accommodative, acute, and mechanical.
Accommodative ET
Due to accommodation. Can do CT with +2 lens
Acute ET
Sudden onset and secondary to a neurological problem or a decompensated phoria.
Mechanical ET
Secondary to restriction.
Secondary ET
Due to either sensory deprivation or consecutive ET after strabismus surgery. Sensory deprivation occurs after age 5 and is a result of trauma or disease
Micro ET
constant, unilateral, eso deviation of less than 10 p.d. that develops before 3 years of age. Must detect with 4BO test.
Infantile or congenital XT
A large deviation that occurs before 6 months of age. Normally alternating.
Acquired XT
Occurs after 6 months of age.
Acute Acquired XT
Sudden onset, constant eco deviation. Can be neurological, trauma, or decompensated.
Mechanical acquired XT
Due to physical restriction of an EOM.
Secondary XT
Sensory XT occurs with acquired vision loss (after the age of 5) and consecutive occurs after surgery.
Micro XT
oxo deviation less than 10. Use a 4 BO test.
Most common binocular dysfunction with TBI
CI
What to prescribe for post traumatic vision sydrome
binasal occlusion or BI prism.
