Ocular Motility/Binocular Vision Flashcards
(244 cards)
1
Q
Listing Plane
A
- X = Horizontal, elevate/depress
- Y = thru line of sight/torsional,
- Z plane = Vertical, abduct/adduct
- X,Y,Z plane (similar to airplane mvmts)
- eye mvmts must fall within listing planes
- secondary position of gaze = rotations about these axes
- Tertiary positions of gaze = looking in oblique directions
2
Q
Muscle Plane
A
- describes the direction of pull and individual EOM can make
- plane passes thru the center of rotation and is determined by the origin and insertion sites of EOM
3
Q
Axis of rotation
A
- perpendicular to the muscle plane around which the eye rotates when acted on by an EOM
4
Q
Tangential point
A
point where muscle tendon first makes contact with globe of the eye
5
Q
Arc of contact
A
area btw tangential pt and pt of insertion of muscle on the globe of the eye, this is the area where muscle exerts its action on the eye
6
Q
Duction
A
monocular rotation
7
Q
Abduction
A
rotation about z-axis, away from midline
8
Q
Adduction
A
rotation about z-axis, towards midline
9
Q
Elevation
A
upward rotation about the x-axis
10
Q
Depression
A
downward rotation about the x-axis
11
Q
Incycloduction
A
rotation about the y-axis such that the upper portion of the eye tilts inward
12
Q
Excycloduction
A
rotation about the y-axis such that the upper portion of the eye tilts outwards
13
Q
Versions
A
Binocular eye mvmts that results in the visual axes of both eyes moving at the same direction (conjugate mvmts)
- purpose is to enlarge FOV and move fovea of each eye to an object for fixation
14
Q
Dextroversion
A
both eyes rotate about the z-axis to the right
15
Q
Levoversion
A
Both eyes rotate about the z-axis to the left
16
Q
Dextrocycloversion
A
Rotations about the y-axis such that the upper portion of both eyes tilts to the pts right
17
Q
Levocycloversion
A
Rotations about the y-axis such that the upper portion of both eyes tilt to the pts left
18
Q
Vergences
A
align the visual axes of both eyes to obtain binocular fixation and fusion
- disconjugate eye mvmts, eyes move in opposite directions
19
Q
Convergence
A
rotate on z-axis towards midline
20
Q
Divergence
A
rotate on z-axis away from the midline
21
Q
Incyclovergence
A
rotate on y-axis such that the upper portion of each eye rotates towards the midline
22
Q
Excyclovergence
A
rotate on y-axis such that the upper portion of they eye rotates away from the midline
23
Q
Primary, secondary and tertiary actions of EOMS
A
“SIN RAD”
24
Q
SR and IR (how many degrees)?
A
23 degrees
25
SO and IO, how many degrees?
54 degrees SO, 51 degrees IO
26
Spiral of Tillaux
MILS
- Medial rectus inserts closest to the limbus (strongest effect when it contracts)
- Superior rectus inserts furthest away from the limbus
27
Donder's Law
- Starting location of the eye and path taken to a unique position of gaze does not influence the orientation of the eye at the final position gaze
- The orientation of the eye for a particular gaze is always the same, regardless of where the eye was initially positioned before moving at the final position of gaze
28
Listing's Law
- eye must rotate around an axes to achieve a given direction of gaze
29
Hering's Law of equal innervation
aka yoked muscles (one from each eye)
- LR and MR
- SR and IO
- SO and IR
30
Sherrington's Law
- agonist and antagonist EOMs of the SAME eye are reciprocally innervated
- SR and IR
- IO and SO
- MR and LR
31
Eye mvmt serves 2 primary purpose
1. Move eye so that fovea aligns with object of interest (saccade, smooth pursuit, vergence)
2. Hold images in place on the retina (fixation, VOR, optokinetic system)
32
Why does the eye constantly move during fixation?
involuntary eye mvmts help continuously shift an img onto neighboring PR, preventing bleaching of the retina, fatigue, subsequent fading or smearing of an img
- minimize troxler effect
33
Troxler effect
fading of peripheral img when eye is fixated on a central object
- small involuntary mvmts occur to help minimize this effect
34
Microsaccades
- intentional conjugate mvmts w/ moderate-high velocity (2-10 degrees/ second) and amp (6 arc mins)
- move fovea back on area of interest after microdrift and microtremors have caused the fovea to shift from the target
- counteract errors from microdrifts and microtremors
35
Microtremors
- Unintentional disconjugate eye mvmts with high frequency (65-75 Hz) and amplitudes of about 10 arc mins
- fastest of the 3 types of mvmts associated with fixation (microsaccades, microdrift)
- disconjugate, neural noise within the brainstem
36
Microdrifts
- disconjugate, unintentional eye mvmts that are larger and slower than microtremors
- velocity of 1 arc min per second and amplitude of 6 arc min
37
Eye mvmts associated with fixation
- microsaccades
- microdrift
- microtremors
38
Vestibulo-Ocular Reflex
- stabilize img on fovea during brief head mvmts by producing eye mvmts of equal magnitude to the head mvmt, but in opposite direction
- occurs rapidly 300 degree/sec and very small latency (15 msec)
- stimulated by enolymph within the semicircular canal
- does not require visual stimulus - will occur even if eyes are closed
- VOR compensates well for fast eye mvmts, reflex begins to fade with uststained head mvms over 30 sec in duration, **optokinetic system takes over**
39
Damage to the vestibular system can cause what?
horizontal nystagmus (damage to vestibular nuclei in brain or vestibular connection to the brainstem/cerebellum or peripheral damage - labyrinth or vestibular nerve of inner ear)
**acute vestibular lesions typically cause nystagmus, while slow-growing lesions do not**
40
Oscillopisa
sensation of objects moving up and down in the VF
41
Vertigo
sensation of the body moving around in the environment even though it is still
42
If vestibular dysfunction is suspected, what testing should be done
caloric testing, oculocephalic testing, and/or rotation testing
43
Oculocephalic testing
dolls head mvmt
44
Caloric testing
- Intact vestibular system = COWS (fast phase)
45
Rotational testing
- rotate pt around in a chair
- slow movement same direction
- fast mvmt opposite direction
46
Jerk nystagmus
- slow and fast phase
- slow phase (drift) = abnormality in fixation
- fast phase = correcting saccade, brings fovea back onto target
- nystagmus named in direction of fast phase
47
Pendular nystagmus
even back and forth mvmt of eyes
48
Null point
direct gaze that nystagmus decr
49
Neutral point
direction of gaze where nystagmus changes direction
50
Physiologic vs pathologic nystagmus
Physiologic = conjugate jerk nystagmus w/o assoc. sx or decr vision
Pathologic = dissociated (disconjugate) eye mvmts with excessive drift, causing decr VA and oscillopsia
51
Ex of physiologic nystagmus
1. End pt nystagmus: small intermittent, apparent in extreme horizontal gaze
2. Optokinetic nystagmus
3. Caloric nystagmus
4. Rotation nystagmus
**all conjugate nystagmus**
52
Congenital (infantile) nystagmus
- birth or <6 months
- affects males 2X more than F
- 60% efferent defect
- 40% afferent defect
- horizontal and conjugate, may be pendular or jerk waveform
53
What ocular conditions can cause nystagmus
- aniridia
- albinism
- achromatopsia
- optic nerve hypoplasia
- optic atrophy
- congenital cataracts
all lead to poor image formation the fovea with subsequent nystagmus
54
Latent nystagmus
- congenital, conjugate jerk nystagmus that incr in velocity and amp when one eye is occluded (ex. during CT)
- horizontal, fast phase towards the fixating eye
- associated with essential infantile esotropia and amblyopia
55
Spasmus nutans
- develops around 8 months after birth
- resolves at 5 yo
- Associated w/ head nodding, head tilt
- asymmetric, unilateral nystagmus
56
Convergence retraction syndrome
- dorsal MIDBRAIN lesion
- convergence and retraction (all CN 3 EOMS firing)
- LR (CN6) still intact causing convergence
- Occurs when pt is looking upgaze
57
Gaze-evoked nystagmus
- jerk nystagmus evoked at extreme gazes
-2' to drug use or posterior fossa dz
58
see-saw nystagmus
elevation and intort in one eye
depression and extort in other eye
59
Optokinetic nystagmus (OKN)
maintains stable image of a moving object while img is still
60
Optokinetic reflex vs OKN
Optokinetic reflexes occur after prolonged head mvmts/ VOR response has faded
OKN occurs to maintain a stable img while head is still
61
At what age does the nasal to temporal optokinetic response occur?
3-4 months
62
OKN drum, slow phase occurs
slow phase = same direction as the drum
longer latency than VOR
63
What should be considered if OKN response is inconclusive?
parietal lobe lesion or decr VA
64
Does VOR require visual stimuli?
No
65
Saccades are initiated by
contralateral FEF
occipitalparietal junction
66
Damage to this portion of the brain can cause decr accuracy and velocity
superior colliculus
67
Velocity and latency of saccades
1000 deg/sec, 200 ms
68
Saccades
very rapid, yoked eye mvmts that move the fovea object of interest in the VF
- most are voluntary, sudden visual, auditory, or peripheral stimuli may elicit involuntary saccades
- voluntary and involuntary
69
Damage to FEF will cause what?
impair saccades to the left
70
most common saccadic error?
undershooting
71
microsaccades
smaller, amplitude and velocity used for reading, occur ~5X per min
72
During saccades, vision is suppressed by which system? (saccadic impression)
cortical
73
Test for saccadic dysfunction
- NSUCO
- DEM
- Readalyzer
74
NSUCO
- perform 5 rounds of saccades
- check head/body mvmts, ability and accuracy of saccades at near and rate 1-5
75
Developmental eye movement test (DEM)
Pt reads a series of numbers vertically and horizontally
Vertical = test for automaticity
Horizontal = test for saccades and automaticity
- similar to King Devick and Pierce saccade test
76
Readalyzer
- test comprehension and reading ability
- 15th percentile is considered evidence of saccadic dysfunction
- similar to Visagraph
77
ex. of saccadic dysfunction
square-wave jerk
- rare, uncontrollable saccades that occur randomly and interfere with fixation
- macrosquare waves if amp is larger than 10 degrees
Ocular flutter
- "spring like"
- multiple, spontaneous, conjugate horizontal saccades that decr in amp over time and occur after series of small saccades or during fixation
Opsoclonus
- advanced form of ocular flutter
- constant series of involuntary conjugate saccades, in multiple direction that occurs only while awake
78
Symptoms of abnormal saccades
- reading issues
- skipping lines, losing place, excessive head mvmts, slow reader, poor comprehension, short attention span
- saccadic dysfunction = trouble copying board and math problems
79
What causes ocular flutter and opsoclonus
cerebellar dz
- MG, parkinsons, alzheimer's, ocular motor apraxia, progressive supranuclear palsy, and internuclear ophthalmoplegia
80
Pursuits are controlled by which part of the brain?
parietal lobe
81
Velocity and latency of pursuits?
50 degrees/sec and 125 msec
82
Test for pursuits
NSUCO = follow clockwise/counterc clockwise rotation (ability, accuracy, head/body mvmts)
Groffman tracing
- trace lines without using guides
83
Oculomotor dysfunction
abnormality in fixation, saccadies, and pursuits
84
Pursuits
slow tracking mvmts that allow continuous fixation of a moving object on the fovea
- voluntary eye mvmts
85
An object moving greater than __ deg/second is no longer able to maintain smooth tracking mvmt
50
- will require pursuit-saccade-pursuit process until target slows down to pursuit threshold velocity
86
A parietal lobe will cause impaired pursuit lesion toward the ___ side
IPSILATERAL
- clinically seen with OKN drum rotating towards side of lesion
87
Abnormality in pursuits can lead to?
poor performance in sports, excessive head mvmts w/ tracking
88
Damage to which part of the brain can cause abnormal smooth tracking eye mvmts?
occipitoparietal junction, brainstem, cerebellum
89
Most common pursuit abnormality
cogwheeling = "step-like" eye mvmts
90
Vergence
- disconjugate mvmts, eyes move in OPPOSITE direction
- allows fusion and binocular vision
91
latency and velocity of vergence mvmts
160msec, slow velocity of 10 deg/sec
92
Different type of vergence mvmts
Tonic
Proximal
Fusional
Accommodative
93
Tonic
- position at rest at distance without a stimulus to convergence or accommodation
- BCVA at distance phoria
94
Proximal
a person's awareness of a near target
95
Fusional
initiated by retinal image disparity and helps eyes compensate to obtain foveal fixation and BV
- analogous to motor fusion
96
Accommodation
convergence initiated by blur and occurs with changes in accommodation
- characterized by AC/A ratio
97
near triad reflex
convergence, accommodation, miosis
98
decompensated phoria
large phoria that pt was able to previously compensate for but is now unable to do so causing tropia/diplopia
99
Comitant deviation
- misalignment of visual axis of each eye that is the same in all positions of gaze
- finding indicates decompensated phoria
100
Noncomitant deviation
- misalignment of the visual axis of each eye that is NOT the same in all positions of gaze
- indicates muscle restriction/palsy
- perform forced duction
101
Noncomitant primary and secondary deviation
primary = deviation of paretic eye when normal eye is fixating
secondary = deviation of normal eye when paretic eye is fixating
- ALWAYS greater than primary deviation due to herring's law of equal innervation
102
Subjective test of comitancy
Red lens test = describe position of red and white light in all 9 positions of gaze
Hess-Lancaster test = views laser grid with red/green gls (red lens in front of normal eye if measuring primary deviation)
- examiner has red flash light, pt is holding green flashlight
- 9 positions of gaze
- to measure secondary deviation, have pt switch red lens to the paretic eye
103
Forced duction
- test anatomical muscle restriction from CN palsy
- concomitant deviation
(+) = eyes does NOT move, anatomical restriction
(-) = eyes move, muscle palsy
104
Differential dx for anatomical muscle restrictions
Graves ophthalmopathy, orbital tumor, entrapment of EOM following trauma, duanes retraction syndrome, brown syndrome
105
Duane's retraction syndrome
- congenital conditions mostly in left eye in females
- 3 types
1. Abduction (MOST COMMON)
2. Adduction (LEAST COMMON)
3. Abduction and adduction
- ALL types assoc w/ globe retraction and narrowing of palpebral fissure with ADDuction (due to violation of sherrington's law)
- common present with eso in primary gaze
106
Brown syndrome
- aka SO tendon sheath syndrome
SO issue
- acquired or congenital (tendon issue or damage/tumor/inflammation)
- unilateral and presents with small hypotropia in primary gaze and limited elevation during ADDuction
- differential dx = IO paralysis, overaction of SO, orbital floor fracture
- THINK BACKWARDS
107
A pt shows hypertropia in the left eye in primary position and hypertropia becomes more pronounced when he looks right and tilts his head left. Which EOM is likely involved?
Left SO
108
Binocular vision
- the motor coordination between 2 eyes align the foveas on the object of interest
- allows for stereopsis, larger FOV, improved performance on visual task, incr CS,
109
Motor fusion
stimulated by retinal disparity that moves eyes to align each fovea with the object
110
Sensory fusion
combine 2 images from each fovea into a single percent in the visual cortex
111
for an object to be seen as single with BV, the image of each retina must be..?
same size, clear, corresponding retinal points
112
Corresponding points
same visual direction by each eye and project to the same area of the visual cortex (corresponding line of sight)
113
Primary vs secondary directions
Primary = going thru fovea
Secondary = all other retinal points
114
Oculocentric vs ego centric
Oculocentric = reference to eye position under monocular conditions(primary/secondary direction)
Egocentric = reference to head under binocular condition
115
Objects falling on horopter
will be seen as a single
116
Panum's fusional space
area around the horopter are still seen as single and in depth
117
Objects that fall outside of panum's fusional area
diplopia
118
BV disorders (2 categories)
1. Nonstrabismic disorders = single vision is present under most circumstances but stresses the visual system causing sx
2. Disorders where BV is absent = diplopia, confusion, strabismus
119
Cover test
- dissociated test, direction and magnitude
- Unilateral CT = measures direction
- Alternating CT = measures magnitude
120
Neutralizing prism used for eso and exo
eso = BO
exo = BI
121
Expected findings for non-presbyopic patients
Distance XP
Near XP
Distance XP = 0-2
Near XP = 0-6
122
Phi phenomenon
Exo = object moves SAME direction as paddle mvmt
Eso = object moves OPPOSITE direction as paddle mvmt
123
Tests that measure magnitude and direction of ocular deviation
CT, maddox rod, modified thorington, VG, fixation disparity
124
Test that measures magnitude and direction of positive and negative fusion vergence ranges
Direct: smooth vergences, step vergence, and vergence facility
Indirect: NRA/PRA, FCC, BAF, and MEM
125
Test that measures convergence amplitude
NPC
126
Test that measures sensory status (suppression and stereopsis)
W4D, Randot
127
Von Grafe
12 BI OD, 6 BU OS
- dissociated vergence
- cannot differentiate if the pt has phoria or tropia
128
Maddox rod
- Stacked prisms, measuring magnitude and deviation
- MR w/ horizontal lines produce vertical img
- MR w/ vertical lines produce horizontal img
Results (assuming MR OD, oriented horizontally)
- orthophoric (line passes thru center of white light)
- exophoric (line to the left of the white light)
- esophoric (line to the right of the white light)
Results (assuming MR OD, oriented vertically)
- line above white light = left hyper
- line below white line = right hyper
129
Double maddox rod
- MR over both eyes
- detect torsional misalignment of the eyes
130
Modified thorington
- dissociated, measure magnitude and direction of phoria
- test done outside of the phoropter w/ card at 40cm
- MR over OD, pt reports number on the card that the red line crosses
131
Fixation disparity
- detects very small misalignment
- unable to detect w/ standard test b/c it still falls within panums fusional area
Devices used for FD:
- Mallet unit
- AO vectograph slide
- Bernell lantern
- Wesson fixation card
- Sheedy disparometer
132
Associated phoria
amt of prism required to neutralize fixation disparity
133
Paradoxical FD
associated and dissociated phorias are in OPPOSITE direction
134
4 types of FD curves
Type 1 = most common w/ sigmoidal shape. Pts asymptomatic
Type 2 = eso disparity
Type 3 = exo disparity
Type 4 = unstable binocular system. Pts may not have associated phoria and may have sx of aniseikonia and poor sensory fusion
135
AC/A ratio
- represents amt of accommodative convergence that occurs with increased accommodation and measured in units of prism diopters
- for every diopter of accommodation, how much convergence or divergence will we have?
136
Calculated AC/A equation
- Pt phoria is measured thru BCVA at distance and near
AC/A = PD + NFD(Pn-Pd)
PD = IPD in cm
NFD = near fixation distance in m
Pn = near phoria
Pd = distance phoria
137
A pt with PD of 64mm has 1.5pd esophoria at distance and 3pd exophoria at 40cm. What is his/her AC/A ratio?
Use calculated AC/A equation: 4.6pd
138
Gradient AC/A
- pt phoria is measured at the same distance but with different lenses to change stimulus accommodation
- measured at 40cm w/ subjective refraction and then +1.00D over subjective refraction
AC/A = (P1-P2)/(SA1-SA2)
- phoria under 1st and second condition
- stimulus accommodation under first and second condition
139
A pt with PD of 64mm is 2pd esophoric at 40cm through their subjective refraction and 10pd esophoric through -1.00D over the subjective refraction. What is his/her ACA ratio?
8/1
140
Which is usually greater?
Calculated AC/A ratio
Gradiant AC/A ratio
Calculated AC/A ratio
141
AC/A norms
4pd
142
tx for pts with high AC/A ratios
respond well to lenses
143
tx for pts with low AC/A ratios
VT or prism, lens power will not significantly alter accommodative convergence
144
Pt with convergence excess (high esophoria at near) and on AC/A ratio of 10pd, an addition of +1.50D at near over the subjective refraction will decr vergence by how much?
The add will decr convergence by 15D
Ex. pt were 10pd esophoria at near through subjective refraction he would be 5 pd exophoria t near through 1.50D over the subjective refraction
145
Smooth vergence testing
- determines amplitude and recovery of fusional vergence
- convergence and divergence respond to retinal disparity in order to maintain sensory fusion
- perform in the phoropter using Risley prism
- Measure NFV first by using BI prisms
- Measure PFV using BO prisms
- Find blur point, breakpoint, recovery point
- Can also test for vertical ranges
- test PFV by adding BO prism, plus lens
test NFV by adding BI prism, minus lens
146
What tests for PFV?
BO prisms
indirectly plus lenses
"BIN or BIM BOP"
BOP = BO positive lens for PFV
147
What tests for NFV
BI prism
indirectly minus lens
"BIN(NFV) or BIM(Minus lens) BOP"
148
What does the blur, break, and recovery point tell you for smooth vergences?
Blur = limit of fusional vergence
Break = limit of fusional AND accommodative vergence
Recovery = assess the flexibility of binocular system to regain fusion after diplopia occurs, should be at least 1/2 the break point
149
Morgan Norms:
Distance BI
Distance BO
Near (40cm) BI
Near BO
Distance BI: x/7/4
Distance BO: 9/19/10
Near (40cm) BI: 13/21/13
Near BO: 17/21/11
150
What does sheard's and percival's criteria tell you?
if vergence ranges are sufficient to account for pts phoria allowing for comfortable and clear BV
- Sheards is most effective for XP
- Percival's best for EP
151
Sheard's criterion
- fusional reserve should be 2X (blur) the demand of the phoria
S = 2/3D - 1/3R
D= phoria
R = compensating fusional vergence (reserve)
BI = EXO, BO = ESO
**ZERO or negative number means no prism is needed**
152
A pt has 8pd exophoria at near and vergence ranges of 17/25/18 BI and 6/9/4 BO. What is the amt and direction of prism that should be prescribed based on sheards criterion?
3.33 BI
153
Percivals Criterion
the smaller fusional vergence should be at least half of the greater fusional vergence reserve
- DOES NOT TAKE INTO ACCOUNT OF THE PTS PHORIA
P = 1/3G - 2/3L
G = greater of the 2 vergences
L = lesser of the two vergences
** P is ZERO OR NEGATIVE, no prism needed**
154
If the pt has 10pd EP with BI vergence 6/10/4 and BO vergence 21/28/22 , what is the amt and direction of prism that should be prescribed based on Percival's criterion?
3pd
155
Step Vergence
- determines amplitude and recovery of fusional vergence system
- performed OUTSIDE phoropter using prism bars
- Start with BI and then repeat procedure w/ BO
156
Vergence Facility testing
- Determines pt ability to make large, rapid, and sustained changes in fusional vergences over a period of time
- use 12 BO/3BI comb flippers
- flip between each as soon as the pt is able to fuse into a single image (BO first)
- Examiner counts number of cycles within 60 seconds
157
Vergence facility testing norms
15 cycles/min
158
NPC
- measures pts ability to converge eyes while maintaining fusion
- Show pt an isolated target just below pts line of sight, slowly bring target towards nose until diplopia or eye drifts out then slowly pull the target away until fusion is seen
159
Norms for NPC
Break 5, recovery 7
160
Accomodation tests
- accommodation accounts for 70-80% of secondary BV disorders
How much accommodation is present?
- push-up test, pull-away test, minus lens test
How accurate is the accommodative response?
- Near retinoscopy (MEM or NOtts), FCC/BCC, NRA/PRA)
How flexible is the accommodative system?
- MAF and BAF
161
Push-up test
- measures amplitude of accommodation
- push up until first sustained blur
- tens to overestimate compared to other methods due to relative distance magnification
162
How do you calculate the following?
- Average amplitude of accomm.
- Minimum aplitude of accomm
- Maximum amplitude of accomm
Average = 18.5 - 0.3(age)
Minimum = 15-1/4(age)
Max = 25 - 0.4(age)
163
Pull away test
- target is held really close to the eye and is slowly pulled away from the eye until pt can JUST read the letter
- minimize variability
164
Minus lens test
- using a phoropter, add minus lens until first sustained blur
- amplitude of accommodation is the amt over the pts PLUS 2.50D (to account for WD)
- the AoA measured with minus lens test is 2.00D less than the amplitude obtained with push-up test
- underestimation due to minification
165
For the pt to be comfortable, how much accommodation needs to be kept in reserve?
1/2 of the accommodative amplitude should be kept in reserve
166
Accommodative facility testing
- Determines flexibility and endurance of the accommodative response
- Use flippers +/-2.00D, counter number of cycles within 60 seconds
- Binocular (first) and monocular
167
Accommodative facility testing results:
- Inadequate clearing of plus and minus
- Inadequate clearing of plus only under binocular and monocular conditions
- Inadequate clearing of minus only under binocular and monocular conditions
- Inadequate clearing of binocular plus or minus, normal clearing of monocular plus or minus
- Inadequate clearing of plus and minus = Poor accommodative facility
- Inadequate clearing of plus only under binocular and monocular conditions = over-accommodation
- Inadequate clearing of minus only under binocular and monocular conditions = deficient accommodation
- Inadequate clearing of binocular plus or minus, normal clearing of monocular plus or minus = vergence issue
168
Normal findings for accomdative facility testing
Ages 13-30 = 8cpm (binocular), 11cpm (monocular)
169
Monocular estimation method (MEM)
- determines accuracy of accommodative response
- near card is attached to retinoscope at eye level with both eyes open
- using vertical beam, examiner observes motion reflex at WD or harmon's distance
- add lens until neutralization
- normal illumination and reading card should be age appropriate
**because its measured binocularly it may reflect binocular or monocular disorder**
170
MEM results:
- plus lens neutralize reflex
- minus lens neutralize reflex
- plus lens neutralize reflex = lag of accomm (acc LESS than demand)
- minus lens neutralize reflex = lead of accomm (acc MORE than demand)
171
Norms for MEM
+0.25 to +0.50D (lag of accommodation)
172
Fused cross cyl (FCC/BCC)
- subjective test
- determines accuracy of accomm. response and ADD for presbyopic pt
- Cross image set at 40cm
- horizontal lines should be sharper at the start of test, add minus or until horizontal lines are sharper
- add plus until vertical lines are sharper. Then reduce plus until pt reports horizontal and vertical lines appear equally sharp
173
Norms for FCC/BCC
+0.25 to +0.75 lag of accomm.
174
NRA/PRA
- determines pts max ability to relax/stimulate accomm
- may determine near add or if the pt has been overminused
- NRA (FIRST) = plus lens added until blur
- PRA = minus lens added until blur
175
When performing NRA/PRA what do the following lenses do to the eye?
Plus lens in NRA
Minus lens in PRA
Plus lens in NRA = relax accommodation, decr convergence. The pt must use PFV to keep the target single
Minus lens in PRA = stimulate accommodation, incr convergence. Pt must use NFV to keep the target single
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Norms for NRA/PRA
+2.50D NRA/-2.50D PRA (should be balanced
- >NRA = pt overminused
- Abnormal binocular AND monocular results = accommodative system issue
- Abnormal binocular but normal monocular results = PFV/NFV issues
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Review: BV norms
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Most common non-accommodative BV disorder
CI
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s/s of CI
Sx: Eyestrain, HA, blurred vision, diplopia, poor concentration, poor reading comprehension, sleepiness, mvmt of print, and pulling sensation of the eyes
signs: Larger XP at near than distance, Low AC/A, reduced NPC, reduced PFV, low lag or lead of accommodation
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What's the difference btw CI and pseudo-CI?
Pseudo-CI is characterized by **accommodative insufficiency**
- borderline PFV ranges and near exophoria
- decr AoA
- low PRA
- respond well to low plus at near (+0.75 to +1.00)
- NPC that improves with low plus lens
True CI
- Reduced NPC
- Reduced PFV
- Low AC/A
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You suspect a 21yo has CI due to an 8pd exophoria at near and receded nPC, but a +2.00 lens at near improves NPC and the pt also has reduced amplitude of accommodation. What is the dx?
Pseudo-CI
- reduced accommodation leading to reduce convergence with moderate XP at near
- reduced NPC that will improve with addition of low plus at near
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sudden sx of CI, what are your ddx?
MS and myasthenia gravis
Pt with true CI will have longstanding sx
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DI
- LEAST common non-strabismic ocular BV disorder
sx: intermittent diplopia at distance that is worse at the end of the day, HAs, fatigue, blurred vision, difficulty focusing from far to near, light sensitivity, motion sickness, nausea
Signs: greater EP at distance than near, low AC/A, reduced NFV at distance
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Important differential dx for DI?
- CN 6 palsy = non-comitant
- while DI will have a large comitant EP
others: basic EP, CE, and divergence palsy
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CE
- will cause greater sx
sx: HAs, eye strain, blurred vision, diplopia, poor concentration, poor reading comprehension, hold reading material too close
- may be asx if suppressing or avoids near task
Signs: greater EP at near, reduced NFV, high AC/A, larger lag of accommodation, low PRA bc of reduced NFV ranges, inability to clear minus lens w/ BAF but MAF will be normal unless pt has accompanying excess
- may be accompanied by accommodative excess or latent hyperopia
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CE ddx
- Ocular inflammation: uveitis,scleritis
- CNS dz: Tertiary syphilis, sympathetic paralysis
- Pharmacological: Parasympathomimetic drugs (phyostigmine, pilocarpine, high does of B1, sulfonamides)
others: basic EP, DI, AE
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DE
sx: most common sx are cosmetic concerns b/c eye turns out or pt covers an eye in bright light. Most common visual sx is diplopia
Signs: Greater XP at distance and becomes more pronounced w/ fatigue, may lead to intermittent XT, high AC/A, PFV ranges are normal at D and N, V pattern exo deviation
Intermittent XT rarely leads to sx of diplopia, suggesting pts suppress an eye or develop ARC to avoid diplopia/confusion
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Basic XP
Sx: eyestrain, HAs, diplopia at D & N, blurred vision at distance and near, poor reading comprehension
Signs: XP that is equal to D&N, normal AC/A, reduced PFV ranges at d&N, reduced NRA, low lag or lead of accomm., inability to fuse BO with vergence facility, inability to clear plus lenses with BAF
ddx = divergence excess, CI
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Basic EP
sx: eyestrain, HA, diplopia, poor concentration, poor reading comprehension, avoidance of near work
signs: EP equal at d&n, normal AC/A, reduced NFV ranges, reduced PRA, high lag of accomm, inability to fuse BI w/ vergence facility testing, unable to clear minus lens
ddx = DI, CE, CN 6 palsy, divergence paralysis
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Vertical phorias
sx: blurred vision at d&n, diplopia, HAs, losing place, skipping lines when reading, poor concentration, motion sickness, nausea, sleepiness
signs: small hyperphoria at d&n, head tilt, reduced PFV and NFV ranges, reduced vergence facility w/ BO and BI, vertical vergences may be constricted (if recent onset vertical deviation) or larger than normal (if vertical deviation is longstanding)
- may contribute to horizontal BV disorders but tx vertical disorder first and horizontal will resolute
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A pt with recent onset, large , non-comitant vertical deviation
should be investigated for underlying systemic pathologies
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Fusional vergence dysfunction
- 3rd most common non-accommodative BV disorder
- sx: eye strain, HAs, blurred vision, diplopia, poor concentration, poor reading comprehension
- signs: normal phoria measurement at d&n, normal AC/A, normal accommodative function, and reduced PFV and NFV ranges at distance and near
- these pts will have abnormal BAF but NORMAL MAF
ddx: accommodative infacility (these pts will fail BAF and MAF)
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AI
Sx: blurred vision, eye strain, HAs, poor reading ability, and comprehension, mvmt of print at near, pulling sensation around eyes
signs: reduced AoA, reduced PRA, high lag of ACC on MEM and/or FCC, inability to clear minus lens with binocular AND monocular ACC facility testing
ddx = AE, accommodative infacility, pseudo CI, XP
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subsets of accommodative insufficiency
Ill-sustained accommodation = normal accommodative testing that fatigues with repitaiton
Accommodative paralysis = pathological or pharmacological causes for reduced accommodation
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Accommodative Excess
Sx: eye strain, HAs, intermittent distance blur after near activities, difficulty shifting focus from far to near, and photophobia
Signs: normal to high AoA, reduced NRA, low lag or lead of accommodation, inability to clear plus lens w/ BAF and MAF, may have pseudo-myopia
ddx = accomm infacility, accom insufficiency, basic EP, convergence excess, convergence excess, accomm spasm
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What if you suspect pseudo-myopia, what should you do?
cycloplegic refraction
- due to accommodative excess or convergence insufficiency
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Define AE
pt over accommodates in respone to any stimulus to accomm
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Accomm spasm
- result of fatigue due to over-stimulation of the acomm system
- Plus lens will reduce sx of accommodative spasm but will not work well for accomm excess
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Accommodative infacility
Eye strain, HAs, blurred vision when shifting focus from d to n, pulling sensation around eyes, mvmt of print and poor reading ability and comprehension
signs: reduced NRA and PRA, difficulty clearing plus and minus lens on BAF and MAF, AoA and MEM/FCC may be normal or abnormal, depending on degree of direction of accommodative inflexibility
ddx = AI, AE, basic EP, CE
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Amblyopia
20/30 or worse
- occurs at the visual cortex
- few cortical connections w/ blurred eye
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Critical period of development of the visual cortex
birth to 7-9 years of age
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MOST sensitive development of the visual cortex
first 2-3 years
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Plastic period
time frame where amblyopia can be treated
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Crowding phenomenon
- pts w/ amblyopia often experience difficulty distinguishing btw letters or words that are close together
- better VA w/ single letters
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Degree of amblyopia
Moderate
Severe
Moderate: 20/40 to 20/80
Severe: 20/100 to 20/400
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Three types of amblyopia
Refractive
Form deprivation
Strabismic
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Form deprivation
aka occlusion amblyopia
- obstruction that blocks clear retinal image in ONE eye
- ex. congenital cataracts, ptosis, corneal opacities
- early dx during the sensitive period is CRITICAL
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Refractive amblyopia
- large amt of uncorrected refractive error in one or both eyes
- 3 types: anisometropic and isometropic amblyopia (anisometropic more likely to lead to amblyopia), Meridional amblyopia
- more hyperopic eye will more likely have anisometropic amblyopia
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Potentially amblyogenic refractive errors
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Strabismus
- binocular misalignment
- constant unilateral strabismus will cause amblyopia NOT alternating strab
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Diplopia
- objects fall on non-corresponding retinal points causing diplopia
- suppression in the peripheral retinal will eliminate diplopia
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Confusion
- each macula viewing dissimilar objects
- suppression at the fovea eliminates confusion
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Other ways to avoid diplopia:
suppression
eccentric fixation
anomalous retinal correspondence
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Eccentric fixation
- non-foveal point is used for fixation in the strabismic eye under monocular conditions
- Esotropes will develop nasal eccentric fixation
- Exotropes will develop temporal eccentric fixation
- CT will be less than the true objective deviation
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Paradoxical eccentric fixation
point used for fixation is OPPOSITE to the direction of the deviation (ex. esotropia developed temporal eccentric fixation)
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Testing for eccentric fixation
Haidinger's brush used to dx eccentric fixation
- Haidinger's brush will be centered on a point other than the fixation target
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Eccentric viewing
- occurs in older pts w/ macular dz
- purposefully using a nonfoveal point to fixate
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Normal retinal correspondence (NRC)
- fovea in each eye has the same visual direction
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Anomalous retinal correspondence
- misalignment develops before age of 5
- non-foveal pt in the deviated eye that is viewing an object of interest becomes "linked" to the fovea of the fellow eye
- new anomalous correspondence ensures that the object will be perceived in the same direction by each eye eliminating diplopia/confusion
- only occur under binocular conditions
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Angle of anomaly
difference between objective and subjective angle of deviation
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Harmonious ARC
- angle of anomaly EQUALS the objective angle
- deviated eye corresponds with f of fellow eye
- subjective angle is 0
- pt will NOT have sx of diplopia or confusion
- deviated eye is always changing depending on where the pt is looking
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Unharmonious ARC
- Angle of anomaly is less than objective angle of deviation
- point in between f and fn (where object hits the retina)
- the subjective angle is NOT equal to 0
- pt WILL have diplopia and confusion (less than NRC)
- usually occurs 2-3 weeks after strabismic sx as visual cortex transition to harmonious ARC
- pt should w/ unharmonious ARC experience diplopia/confusion but do not b/c of snesory adaptation
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Paradoxical ARC
2 types:
Type 1 PARC:
- point used to fixate object is FURTHER AWAY from the fovea than fn (where object hits the retina)
- subjective angel of deviation is in the OPPOSITE direction of the objective angle of deviation (ex. pt thinks he's an exo but CT measured eso)
- pt will have worse diplopia/confusion than NRC
Type 2 PARC:
- occurs when fn' moves in direction OPPOSITE to deviation
- subjective angel of deviation to be greater than objective angle
- pt will think he has a larger deviation than what we measure on cover test
- both subjective and objective angles of deviation are in the same direction
- pts will have worse diplopia and confusion than if they had NRC
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Covariance
- phenomenon where the type of correspondence shifts depending on which eye is fixating
- covariance, harmonious ARC is used when normal fixating eye is fixating
- NRC is used when strabismic eye is fixating
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Review:
Harmonious ARC
Unharmonious ARC
Paradoxical ARC
Harmonious ARC: angle of anomaly = objective angel of deviation, NO DIPLOPIA
Unharmonious ARC: angle of anomaly < objective angle of deviation, DIPLOPIA PRESENT BUT LESS THAN NRC
Paradoxical ARC: angle of anomaly > objective angle of deviation, GREATER DIPLOPIA than NRC
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A pt has 12pd esotropia on objective CT and orthophoria on subjective MR testing. What type of anomalous correspondence does the pt have?
Objective-Subjective = Angle of anomaly
Objective = 12
Angle of anomaly = 12
HARC
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A pt has 12pd esotropia on objective CT and 8 ET on subjective MR. What type of anomalous retinal correspondence does the pt have?
UHARC
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Test for ocular deviation and sensory anomalies:
Ocular alignment
Eccentric fixation
Anomalous retinal correspondence
Sensory status
Test for ocular deviation and sensory anomalies:
Ocular alignment: Hirschberg/Krimsky, Bruckners, major amblyoscope, 4 BO test
Eccentric fixation: Haidingers brush, Maxwell's spot
Anomalous retinal correspondence: Bagolini test, after image test
Sensory status: W4D, stereopsis
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Hirschberg
- test for ocular misalignment
- light held at 50 cm and examine corneal reflex (purkinje image)
- Angle lambda under monocular conditions **0.5mm nasal**
- esotropic (light displaced temporally) = ADD 0.5mm
- exotropic (light displaced nasally) = SUBTRACT 0.5mm
- 1mm shift = 22pd
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Angles under monocular condtions
**Angle kappa**: angle btw pupillary axis and visual axis (line passing from fovea through the nodal point of the eye). Most closely approximates angle lambda
**Angle alpha**: angle btw visual axis and optical axis (line passing through the nodal point that is normal to the cornea)
**Angle gamma**: angle btw optical axis and the fixation axis (line extending from fixation point through center rotation of the eye)
**angle lambda is the only one we can clinically measure**
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Krimsky
- measures magnitude of deviation using prism
- corneal reflex displaced nasally (use BI prism)
- corneal reflex displaced temporally (use BO prism)
- corneal reflex displaced upwards (use BD)
- corneal reflex displaced downwards (use BU)
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Bruckner test
- detect strabismus, anisometropia, and/or media opacities in infants
- want to see equal red reflexes
- 1m, the eye with the brighter reflex is the eye with the higher uncorrected power
- at 3-4m, the eye with the darker reflex will have the higher uncorrected power
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4 BO test
- measures small central suppression scotoma 2' to microstrabismus (<10pd Not visible on CT)
4 BO over OD
- OS makes outward mvmt and refixate = NO suppression OD or OS
- OS moves outward but does not refixate = suppression of OS
- OS no mvmt or refixation = OD suppression
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Visuoscopy
- detect eccentric fixation
- pt looks at the center of the grid target under monocular conditions, examiner views foveal light reflex in relation to the center of the grid
- FLR centered = No eccentric fixation
- Grid center is superior to FLR = superior EF
- Grid center is inferior to FLR = inferior EF
- Grid is temporal to FLR = temporal EF
- Grid is nasal to FLR = nasal EF
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After image test
- type of retinal correspondence
- flash pt with fixating eye w/ horizontal light and deviating eye with vertical flash
- using cortical phenomenon
- NRC = perfect cross
- ARC = imperfect cross
- esotropia OD = vertical line to left
- exotropia OD = vertical line to right
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Bagolini lens
- most sensitive test for retinal correspondence
A = NRC if no tropia OR ARC if tropia w/ CT
B = OS suppression
C = OD suppression
D = XT w/ NRC or UARC
E = ET w/ NRC or UARC
F = central scotoma without squint
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4 levels of sensory fusion
Zero degree = NO FUSION, monocular or suppression
First degree = dissimilar objects, super imposition
Second degree = similar objects w/ suppression checks, flat fusion (Single img but NOT stereo), pt does NOT have diplopia, uses motor fusion only
Third degree = stereopsis (motor and sensory fusion)
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W4D
- detects suppression and flat fusion ability (secondary fusion)
- indicated if test is below 40 seconds of arc
- pt wears green/red gls (OD w/ red) while viewing 4 dots (1 white, 1 red and 2 green)
NORMAL:
OD = will see vertical reds
OS = 3 greens
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W4D interpretation:
2 red dots
3 green dots
4 dots
5 dots
2 red dots: OS suppression
3 green dots: OD suppression
4 dots: Flat fusion without suppresion
5 dots: diplopia
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W4D in room lighting vs dark room
Room light = shallow and small suppression scotoma
Dark room = large and deep suppression scotoma
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Stereopsis
2 target types: contour and global
- pt should be wearing habitual gls
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Contour testing
- Ex. Wirt circles, Titmus fly, animals
- monocular cues
- better at detecting peripheral stereopsis (>60 sec or arc)
243
Global testing
- uses random dots
- NO monocular cues
- good at detecting constant strabismus
Ex. anaglyphs and polaroid targets
- Expected results 20 sec of arc
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Horror fusionis
- pts with heterotropia are unable to obtain fusion even with prism
- as images brought closer with prism, they eventually jump over each other rather than fusing
