Binocular Vision (Done) Flashcards
How are angles S, H, and A measured, respectively?
S= Maddox rod or red lens test H= cover test w/ prism bar A= after-image test, or indirectly calculating form angles H & s
What does it mean when a test is a Dissociated test?
A test that breaks Fusion! (ex. like cover test)
What is Phi Phenomenon?
the patient’s perception of movement opposite the direction of deviation of an eye as it is uncovered
»ex. pt. with an esophoria will perceive an image moving to the left as the paddle is switched from covering the left to the right eye (motion in OPPOSITE direction of movement of paddle)
»For exophoria»motion in SAME direction of movement of paddle
When testing a patient for a vertical deviation, if the patient has a right hypertropia and the red lens is over the right eye, how will this appear to the patient?
The red line will appear below the center line»if it is below then it is hyper
In this situation, if the line would have been above, then we could say the patient has a LEFT hyper instead of a right hyper
What is Fixation disparity?
Very small misalignment of the visual axes that is not observed with standard tests for ocular alignment. (still within Panum’s fusional area)
The amount of prism required to neutralize fixation disparity is termed the ______ phoria.
Associated phoria
There are 4 types of fixation disparity curves»Which ones represent Type 2 and 3?
Type 2= eso disparity
Type 3= exo disparity
What is the formula for determining Calculated AC/A ratio?
AC/A= PD (cm) + NFD (m) (Pn-Pd)
Pt. has PD of 64 mm and 1.5PD esophoria at distance and 3PD exophoria at 40 cm. What is her AC/A ratio?
6.4cm+0.4m(-3-(+1.5))= 4.6 PD
What is the formula for calculating Gradient AC/A?
AC/A= (P1-P2)/ (Sa1-Sa2)
Phoria under 1st and 2nd condition
Accommodative stimulus under the 1st and 2nd condition
Patient with 64mm PD is 2 PD esophoric at 40 cm through their subjective refraction and 10PD esophoric at 40 cm through -1.00D over the subjective refraction. What is his/her AC/A ratio?
8:1
»Remember, calculated AC/A ratio will be GREATER than gradient AC/A ratio due to the added proximal convergence when the phoria is measured at near
Patients with High AC/A ratios usually respond better to which form of treatment?
Spherical lens treatment
Patients with Low AC/A ratios usually respond better to which form of treatment?
Prism or Vision therapy
Which lenses indirectly test PFV?
Plus lenses»remember BOP (base out for PFV too)
Which lenses indirectly test NFV?
Minus lenses»remember BIM (base in for PFV too)
Why should NFV ranges always be performed before PFV ranges?
Convergence of the eyes may interfere with the test results if you don’t!
The blur point during smooth vergences represents the limit of _______ vergence.
Fusional vergence
The break point during smooth vergences represents the limit of _______ and _________ vergences.
Fusional and Accommodative
What are Morgan’s expected findings for Distance/Near BI/BO?
Distance BI X/7/4
Distance BO 9/19/10
Near BI 13/21/13
Near BO 17/21/11
What is Sheard’s criterion? What is the calculation for determining Sheard’s criterion?
Compensatory fusional vergence reserve should be at least TWICE the demand of the phoria
S= 2/3 phoria- 1/3 compensating fusional vergence
Pt. has 8PD exophoria at near and vergence ranges of 12/25/18 BI and 6/9/4 BO. What is amount and direction of the prism that should be prescribed based on Sheard’s criterion?
S= 2/3 (8) - 1/3 (9) = 2 PD BI
What is Percival’s criterion? What formula is used to calculate it?
The smaller fusional vergence reserve should be at LEAST HALF of the greater fusional vergence reserve.
»P = 1/3 G- 2/3 L
G= greater of the 2 vergences
L= lesser of the two vergence ranges
Pt. has 10 PD EP’ with BI vergence 6/10/4 and BO vergence 21/28/22, what is the amount and direction of prism that should be prescribed based on Percival’s criterion?
P= 1/3 (21) - 2/3 (6) = 3 PD BO
What is the expected finding for Vergence facility testing values?
15 cycles/minute
For the Minus lens test, how do you determine the correct amplitude of accommodation?
It is the amount of Minus added over the patient’s prescription PLUS 2.50D to account for WD @ 40cm.
Why does the Pull-away test have an advantage over the Push-up test for calculating accommodative amplitude?
Pull-away test minimizes variability in the subjective interpretation of “first sustained blur” AND avoids the effect of relative distance magnification with push-up test.
The AofA measured with the minus lens test is __D LESS than push-up amplitudes due to MINIFICATION of the image as minus lenses are added
2.0 D less than push-up
What are the expected findings for BAF and MAF for patients aged 13-30?
8 cpm (binocular) and 11 cpm (monocular)
+ lenses cause relaxation of accommodation. in order to keep target single, the patient must use ______ to converge the eyes back to the target.
PFV
(-) lenses cause stimulation of accommodation. in order to keep target single, the patient must use ______ to diverge the eyes back to the target.
NFV
What are all of the abnormal values associated with Convergence Insufficiency?
Larger exo @ near, low AC/A, receded NPC, reduced PFV ranges, low lag or lead of accommodation (pt. trying really hard to converge, there for pt. overaccommodates)
»Pt. also has low NRA»Remember BIM AND BOP»anytime pt. has trouble clearing BO, they will have trouble clearing plus lenses too
What are all of the abnormal values associated with Divergence Insufficiency?
Larger eso @ distance, low AC/A, reduced NFV ranges, low lag or lead of accommodation
»Differential is CN VI palsy
What are all of the abnormal values associated with Convergence Excess?
Larger eso @ near, high AC/A, reduced NFV ranges, larger lag of accommodation (trying to acc. as little as possible so as to not stimulate convergence), also low PRA
What are all of the abnormal values associated with Divergence Excess?
Larger exo @ distance, high AC/A, normal PFV ranges @ D & N
What will the clinical findings be in Fusional Vergence Dysfunction?
normal phorias @ D & N, normal AC/A ratio, normal accommodative function, reduced PFV and NFV ranges at D & N
What will the clinical findings be in Accommodative Insufficiency?
Reduced AofA, reduced PRA, high lag of accommodation, inability to clear (-) lenses w/ binocular and monocular accommodative facility testing
What will the clinical findings be in Accommodative Excess?
normal to high AofA, reduced NRA, low lag or lead of accommodation, inability to clear (+) lenses with BAF or MAF
»Look out for Pseudo-myopia!
Amblyopia occurs at the level of the ____________.
Visual cortex
________________ is usually a result of fatigue due to over-stimulation of the accommodative system.
Accommodative Spasm
What is eccentric fixation definition?
Occurs when a non-foveal point is used for fixation in the strabismic eye
What is eccentric viewing?
Occurs in older patients due to macular disease
»pt. will first move to the fovea for fixation before moving to the eccentric viewing point to obtain better visual acuity
If an adult develops adult onset strabismus, what type of retinal correspondence will they develop?
Normal Retinal Correspondence
|»_space;will still have NRC because they are past the critical point
A patient has a 12 PD esotropia on objective CT and orthophoria on subjective Maddox rod testing. Which type of anomalous correspondence does the patient have?
Harmonious ARC
»esotropia measured with CT is offset by the change in corresponding retinal points, reflected in the patient’s orthophoric subjective response to the Maddox rod
Which tests are used to determine ocular alignment?
Hirschberg/Krimsky test, Bruckner test, 4 BO test
Which tests are used to determine Eccentric fixation?
Visuoscopy, Haidinger’s brush, Maxwell’s spot
Which tests used for Anomalous retinal correspondence?
After image test and Bagolini lens test
What is angle Lambda?
The angle between the pupillary axis (through center of pupil) and the line of sight (through the fovea)
»Angle lambda is measured under monocular conditions and is 0.5 mm nasal in each eye
If the corneal reflex is displaced TEMPORALLY, angle Lambda must be _________ to the gross eso deviation to obtain the true deviation.
ADDED
If the corneal reflex is displaced NASALLY, angle Lambda must be _________ to the gross eso deviation to obtain the true deviation.
SUBTRACTED
What is Angle Kappa?
Angle between pupillary axis and the visual axis (line passing from fovea through the nodal point)
What is Angle Alpha?
Angle between the pupillary axis and the optical axis
What is Angle Gamma?
Angle between the optical axis and the fixation axis
|»_space;Angle Lambda is the only angle we can clinically measure!
How does Krimsky test differ from Hirschberg test?
Hirschberg measures the deviation, while Krimsky NEUTRALIZES with prism the deviation.
If the corneal reflex is displaced upwards in one eye, add _____ prism in front of the normal eye until the same endpoint is reached.
Base Down
If the corneal reflex is displaced downwards in one eye, add _____ prism in front of the normal eye until the same endpoint is reached.
Base Up
What distance do you test with Bruckner?
If the reflexes are unequal, the darker reflex corresponds to what?
If the pt. has strabismus the deviated eye will have what type of reflex?
80-100 cm away from midline
»Darker means eye has media opacity, or higher uncorrected refractive error
»Strabismic eye will be BRIGHTER, not darker
For 4 BO test, assuming 4 BO is placed in front of OD» if OS makes an outward movement and then re-fixates on the target, what does this indicate?
No suppression of OD or OS
For 4 BO test, assuming 4 BO is placed in front of OD» if OS makes an outward movement but DOES NOT re-fixate on the target, what does this indicate?
Suppression of OS
Remember, 4BO over OD will cause OD to move in and left eye to move out (because of Yoked prism movements)
For 4 BO test, assuming 4 BO is placed in front of OD» if OS DOES NOT move outward and DOES NOT re-fixate on the target, what does this indicate?
This would indicate OD suppression
If a patient has an OD exotropia, what will the image look like on After-Image test?
The vertical line will appear displaced towards the right
|»_space;If it was esotropia it would appear to the left side (“crossed”)
How are the Bagolini lenses oriented on the patient?
OD sees striations at 45 degrees, while OS sees striations at 135 degrees»therefore, if pt. suppresses left eye, patient will see one line at 45 degrees
During Bagolini lens test which possible reasons would the patient see an “X” through the lenses?
- NRC if cover test shows no tropia
2. HARC if cover test shows tropia
During Bagolini lens test which possible reasons would the patient see a “V” through the lenses?
Esotropia with NRC or UHARC
During Bagolini lens test which possible reasons would the patient see an “upside down V” through the lenses?
Exotropia with NRC or UHARC
Patients who suppress only at distance and only with the room lights on have a ________________.
Shallow and small suppression
Patients who suppress only at distance and near with the room lights dim have a ________________.
Large and deep suppression
What is contour testing?
What are examples?
uses laterally displaced targets with MONOCULAR cues.»better at testing peripheral stereopsis
> > Wirt circles, Titmus fly, animals
> > expected results 20 seconds of arc contour and an appreciation for global stereo
What is Horror fusionis?
Describes when patients with a heterotropia are unable to obtain fusion even with the use of prism. As images are brought together with prism, they eventually jump over each other rather than fusing.
What deviation is an Overacting inferior oblique going to cause?
Hyperdeviation when ADducting
What is Dissociated Vertical Deviation (DVD)?
Excyclotorsion with an upward movement and incyclotorsion with a downward movement.
What is Latent nystagmus?
Nystagmus that is manifest with one eye covered.
How should Midline Shift Syndrome be treated?
Yoked prism with the base TOWARDS the neglected side.
If a patient has a stroke affecting left side of brain, visual midline shift will be away from affected side (towards the left). Therefore, what type of prism should the patient be given?
Yoked prism with based towards the RIGHT should be used for treatment
