1
Q
Where does the visual axis pass from and through? And where do the visual axes of the 2 eyes intersect at
A
pass from the fovea through nodal point of the eye to point of fixation. In normal BSV visual axes of 2 eyes intersect at the point of fixation to give BSV
2
Q
what does orthophoria mean
A
perfect ocular alignment in absence of any stimulus for fusion
3
Q
What does heterophoria mean
A
tendency of eyes to deviate when fusion blocked (latent squint)
exo/esophoria. When fusion insufficient to control imbalance then phoria decompensates and associated with binocular discomfort (Asthenopia) or diplopia
4
Q
What is heterotropia
A
manifest deviation in which visual axes do not intersect at the point of fixation
5
Q
What are some causes of heterotropia
A
images from 2 eyes misaligned so diplopia present- image from deviating eye suppressed at cortical level
childhood squint occurs due to failure of binocular fusion mechanism
failure of fusion due to poor vision in one eye may cause heterotropia in adulthood or squint due to muscle weakness
latent/ manifest deviation commonest form of strabismus
6
Q
What is the anatomical axis
A
line passing from posterior pole through centre of cornea. Because fovea is slightly temporal to anatomical centre of posterior pole of eye, visual axis does not correspond to anatomical axis of the eye
7
Q
What is the angle kappa
A
angle about 5 degrees subtended by visual and anatomical axis. Angle is + (normal) when fovea is temporal to centre of posterior pole resulting in nasal displacement of corneal reflex and negative when converse
8
Q
What does a large angle kappa look like
A
may give appearance of squintwhen none present (pseudo squint) seen most commonly as pseudoexotropia after displacement of macula in ROP where angle may exceed +5 degrees
9
Q
What angle are the lateral and medial orbital walls at with each other
A
45 degrees
10
Q
What angle does the orbital axis form with both lateral and medial walls of the orbit
A
22.5 or 23 degrees
11
Q
What angle does the visual axis form with the orbital axis
A
23 degrees
12
Q
What is the listing plane
A
imaginary coronal plane passing through centre of rotation of globe. Globe rotates on axes of Fick which intersect in Listing plane
13
Q
How does the globe rotate on vertical Z axis
A
left and right
14
Q
How does the globe rotate on X axis
A
up and down
15
Q
How does the globe move on Y axis
A
Torsional
16
Q
When the eye is in primary position what are the actions of medial and lateral rectus
A
medial- adduction in primary position
lateral- abduction in primary position
17
Q
What angle does the vertical recti form with the visual axis
A
run in line with orbital axis. Form 23 degrees with visual axis
18
Q
What are the primary and secondary actions of the vertical recti
A
SR- Elevation, secondary adduction/ intorsion
IR- Depression, adduction/ extorsion
19
Q
What happens in terms of muscle actions (vertical recti) when the globe is abducted 23 edgrees
A
visual and orbital axes coincide so SR only act as elevator- no secondary action, IR acts as depressor.
So this is optimal position for testing function of the vertical recti
20
Q
What other actions could be seen if the globe was adducted 67 degrees in terms of vertical recti
A
Angle between visual/ orbital axes would be 90 degrees
SR only action is intort eye
IR only action is extort eye
21
Q
What is the sprial of tillaux and where do the muscles insert posterior to limbus
A
imaginary line joining insertions of 4 recti and important landmark. MR insertion 5.5mm, then IR 6.5mm, LR 6.9mm, SR 7.7mm
22
Q
What angle do the oblique muscles form with the visual axis
A
51 degrees
23
Q
What are the primary and secondary actions of the superior and inferior oblique
A
SO- Primary intorsion. secondary Depression and abduction
IO- Primary extorsion, secondary Elevation and abduction
24
Q
When the globe is adducted 51 degrees what are the sole actions of the obliques
A
Visual axis coincides with line of pull of muscle.
SO acts as depressor
IO acts as elevator
25
What are the functions of muscle pulleys
effective origins of recti. play important role in eye movement coordination by reducing effect of horizontal movements on muscle actions and vice versa
26
What kind of muscle patterns does pulley displacement cause
V and A patterns
27
What are ductions
monocular movements around axis of Fick- adduction/ abduction/ elevation/ depression/ intorsion/ extorsion.
Tested by occluding fellow eye and asking patient to follow target in each direction of gaze
28
What are versions
binocular simultaneous conjungate movements (in the same direction so angle between eyes remains constant)
Dextro/ laevoversion (gaze right/ left), elevation/ depression.
dextroelevation/ dextrodepression (gaze up and right/ gaze down and right)/ laevoelevation/ laevodepression (gaze up and left/ gaze down and left)
Laevocycloversion (torsional movements)
29
What are vergences
binocular simultaneous disjugate movements (in opposite directions so angle between eyes changes) Convergence is simultaneous adduction and divergence outwards movement.
30
What are the 4 components of reflex convergence
tonic convergence- implies inherent innervational tone to MR
proximal convergence- indued by psychological awareness of near object
Fusional convergence- optomotor reflex maintains BSV by ensuring similar images projected onto corresponding retinal areas of each eye. Initiated by bitemporal retinal image disparity
Accommodative convergence- induced by accommodation as part of synkinetic near reflex
31
What is the normal AC/A ratio
3-5 prism dioptres. Means that 1D of accommodation associated with 3-5 prism dioptres of accommodative convergence.
32
What is the near triad
changes in accommodation, convergence and pupil size
33
What are the six cardinal gaze positions and which muscles cause these movements
dextroversion (RLR + LMR)
laevoversion (LLR + RMR)
dextroelevation (RSR + LIO)
laevoelevation (LSR +RIO)
dextrodepression (RIR + LSO)
laevodepression (LIR + RSO)
34
What are the nine diagnostic positions of gaze
six cardinal positions + primary position + elevation + depression
35
What are agonist antagonist muscle pairs
muscles of same eye moving eye in opposite direction. eg RLR antagonist to RMR
36
What are synergist muscle pairs
muscles of same eye move in the same direction eg RSR+ RIO
37
What are yoke muscle pairs
contralateral synergists- pairs of muscles, one in each eye produce conjugate ocular movements eg yoke of LSO is RIR
38
What is the Sherrington Law of reciprocal innervation
increased innervation to EOM eg RMR accompanied by reciprocal decrease in innervation to antagonist eg RLR. Applies to both vergence and versions
39
What is the Hering law of equal innervation
during any conjugate eye movement, equal and simultaneous innervation flows to Yoke muscles. If paretic squint- innervation to both eyes symmetrical and determined by fixating eye eg LLR palsy if right eye used for fixation there will be inward deviation of left eye due to unopposed action of antagonist of paretic LLR (LMR)
40
What is a secondary deviation
In a paretic squint when the secondary deviation exceeds primary deviation
41
What is muscle sequelae
primary underaction- LSO
Secondary overaction of contralateral synergist/ yoke- RIR
Seconadary overaction + late contraction of unopposed ipsilateral antagonist (LIO- sherrington law)
Secondary inhibition of contralateral antagonist (RSR Hering and Sherrington law)
42
What is the horopter
imaginary plane in external space relative to both the observers eyes for a given fixation target, all points on which stimulate corresponding retinal elements and are therefore seen singly and in the same plane. Passes through intersection of visual axis and includes fixation point in BSV
43
What is Panum fusional space
zone infront and behind the horopter in which objects stimulate slightly non corresponding retinal points (retinal disparity)
44
What are the normal prism dioptre values for convergence/ divergence/ vertical and cyclovergence
convergence- 15-20 PD distance and 25PD for near
Divergence- 6-10PD for distance and 12-14PD for near
Vertical 2-3PD
Cyclovergence about 8 degrees
45
How does the ocular sensory system in children adapt to anomalous states of confusion and diplopia in children
suppression
abnormal retinal correspondence (ARC).
Due to plasticity of developing visual system in children under 6-8 years. Occasional adults who develop acute strab can ignore second image after a time and dont complain of diplopia
46
What is suppression
involves active inhibition by visual cortex of image from one eye when both eyes open. Stimuli for suppression are diplopia/ confusion and blurred image from one eye resulting from anisometropia/ astigmatism
47
What is central vs peripheral suppression
central- image from fovea of deviating eye is inhibited to avoid confusion. Diplopia eradicated by process of peripheral suppression where image from peripheral retina of deviating eye is inhibited
48
What is monocular or alternating suppression
suppression monocular when image from dominant eye always predominates over image from deviating eye so image from deviating eye constantly suppressed. This leads to amblyopia. When suppression alternates from one eye to another amblyopia less likey to develop
49
What is facultative or obligatory suppression
facultative- occurs only when eyes are misaligned. Obligatory- present all the time. Irrespective if eyes are deviated or straight. Examples of facultative are intermittent exotropia/ duane syndrome
50
What is abnormal retinal correspondence
a condition where non corresponding retinal elements acquire a common subjective visual direction eg fusion occurs in presence of small angle manifest squint. Fovea of fixating eye paired with non foveal element of deviated eye. binocular response in ARC never as good as normal bifoveal BSV. represents a positive sensory adaptation to strabismus (as opposed to negative adaptation by suppression) allowing some BSV in heterotropia. Most frequently seen in microtropia (Small angle esotropia).
51
What are the consequences of strabismus
fovea of squinting eye suppressed to avoid confusion
diplopia will occur since corresponding retinal elements receive different images
to avoid diplopia, patient develops either peripheral suppression of squinting eye or ARC
If constant unilateral suppression this leads to strabismic amblyopia
52
What are some examples of motor adaptation to strabismus
face turn
head tilt
chin elevation/ depression
53
What is a face turn motor adaptation to strabismus
control a purely horizontal deviation eg LLR paralysis, diplopia occurs in left gaze. Face turned to left deviating eyes to the right away from field of action of weak muscle and area of diplopia. Face turn can also happen in paresis of vertically acting muscle to avoid side where vertical deviation is greatest eg in RSO weakness, face turned to left
54
What is a head tilt motor adaptation to strabismus
adopted to compensate for torsional and or vertical diplopia. In RSO weakness right eye elevated and head tilted to the left towards the hypotropic eye. Reduces vertical separation of diplopic images permitting fusion
55
What is a chin elevation/depression motor adaptation to strabismus
used to compensate for weakness of an elevator/ depressor muscle or minimize horizontal deviation when A or V pattern present
56
What is amblyopia
unilateral or rare bilateral decrease in VA caused by form vision deprivation and or abnormal binocular interaction for which there is no organic pathology of eye / visual pathway
57
What are the 5 causes of amblyopia
Strabismic amblyopia
Anisometropic amblyopia
Stimulus deprivation amblyopia
Bilateral ametropic amblyopia
Meridonal amblyopia
58
What is strabismic amblyopia
abnormal binocular interaction where there is continued monocular suppression of deviating eye
59
What is anisometropic amblyopia
caused by difference in refractive error between eyes and may result from difference of as little as 1D. More ametropic eye receives a blurred image, in a mild form of visual deprivation. Associated with microstrabismus and may co-exist with strabismic amblyopia
60
What is stimulus deprivation amblyopia
results from vision deprivation. May be unilateral/ bilateral and is typically caused by opacities in media eg cataract or ptosis covering pupil
61
What is bilateral ametropic amblyopia
results from high symmetrical refractive errors usually hypermetropia
62
What is meridonal amblyopia
results from image blur in one meridian caused by uncorrected astigmatism usually >1D persisting beyond period of emmetropization in early childhood
63
What is the crowding phenomenon in amblyopia
In absence of organic lesion, difference in BCVA of 2 snellen lines or more is indicative of amblyopia. VA in amblyopia better when reading single letters than letters in a row. This is the crowding phenomenon
64
What are the treatments for amblyopia
rule out organic disease first. Trial of patching. Usually successful upto 7-8 years in strabismic amblyopia and longer (in teens) for anisometropic amblyopia where good BSV present.
- Occlusion
- Penalization
65
What is occlusion therapy for amblyopia
patch the better seeing eye- younger patient better outcome but risk of inducing amblyopia in good eye. Better VA at start of treatment shorter duration of occlusion needed. If no improvement in 6 months, further treatment unlikely to be fruitful
66
What is penalization therapy for amblyopia
Normal eye blurred with atropine- works best in mild/mod amblyopia VA better than 6/24 especially when due to anisometropic hypermetropia. Patch occlusion likely to produce quicker response than atropine which has been used when compliance to patch occlusion is poor. Weekend instillation may be adequate
67
In children, the later the onset of esotropia is there a greater likelihood of accommodative component to deviation?
yes
68
What are some methods to testing VA in preverbal children
fixating and following (use a face as target)
comparison between behaviour of 2 eyes. occlusion of one eye if strongly objected by the child indicates poor acuity in fellow eye.
Fixation behaviour- used to establish unilateral preference if manifest squint present. Fixation graded as central/ non central and steady or unsteady (observe corneal reflections).
10PD test- promotion of diplopia using 10PD vertical prism. Alternation between diplopic targets suggest equal VA
Rotation test
Preferential looking tests
Pattern VEP
69
What tests can be used in verbal children to assess VA
Tests below should be performed at 3-4 metres from target.
2 years- crowded Kay pictures
3 years- match letter optotypes eg Keeler LogMar/ Sonksen/ Otago crowded tests or Kay pictures if difficult
Older children- may use crowded letter tests/ naming/ matching them. LogMAR tests common and preferable to Snellen
70
What tests are used for stereoacuity
Random dot tests like TNO, Frisby are most definitive evidence of high grade BSV. Where this is weak and or based on ARC, contour based tests eg Titmus may be more reliable
71
What is the titmus test
3D polarized vectograph comprising 2 plates in form of booklet viewed through polarized spectacles. Specs worn before plates viewed. On the right large fly on left series of 9 squares and animals. Perform the test at distance of 40cm
72
What stereoacuities are the various titmus test images at
fly- 3000 seconds gross for young children
animal- 400-100 seconds
circles graded 800-40 seconds
If child has <800 seconds of steropsis and prefers fixing with right eye (left suppression), bottom circle of first square of 4 circles displaced to left and vice versa if fixing with left eye
73
What is the TNO test
random dot test. 7 plates of randomly distributed paired red/ green dots viewed with red green spectacles measures from 480 down to 15 seconds of arc at 40cm
74
What is the Frisby test
3 transparent plastic plates varying thickness. On each plate there are 4 squares of randomly distributed shapes. One square contains hidden circle. No special glasses needed as disparity 600-15 seconds is created by plate thickness. Working distance must be measured
75
What is the Lang test
does not need special glasses. targets (Star/ moon/ car/ elephant) are seen alternately by each eye through the built in cylindrical lens element. Dot displacement creates disparity 1200-200 seconds and patient asked to name or point to a simple shape eg star
76
What are some tests for binocular fusion in infants without manifest squint
Base out prism test
Binocular convergence test
77
What is the base out prism test for testing binocular fusion in infants without manifest squint
A 20PD base out prism infront of one eye (right eye). This displaces retinal image temporally with resultant diplopia.
There will be a shift of right eye to left to resume fixation (right adduction) with corresponding shift of left eye to left (left abduction) with Hering law.
Left eye will then make a corrective re-fixational saccade to right (left re-adduction)
On prism removal, both eyes move to the right
Left eye then makes an outward fusional movement
Most children with good BSV should overcome a 20PD from age of 6 months. If not weaker prism 16/12 PD may be tried but response more difficult to identify
78
What is the binocular convergence test for binocular fusion in infants without manifest squint
simple convergence to interesting target can be shown from 3 to 4 months. Both eyes should follow approaching target symmetrically to the nose. Over convergence in infant may indicate incipient esotropia. Divergence may be due to a tendency to divergent deviation or lack of interest
79
What are some tests for sensory anomalies
Worth 4 dot test
Bagolini striated glasses
4PD prism test
Synoptophore
80
What is the worth 4 dot test/ how is it done and what are the results interpretation
dissociation test used both distance and near fixation- differentiates between BSV/ ARC and suppression
patient wears green lens infront of right eye filters out all colours except green and red lens in left eye filters out all colours except red. A box with 4 lights: 1 red, 2 green, 1 white is viewed
Results
If BSV present all 4 lights seen
4 lights + manifest deviation-harmonious ARC
if 2 red lights seen- right suppression
if 3 green lights seen- left suppression
if 2 red + 3 green lights seen- diplopia present
if green/ red lights alternate- alternating suppression present
81
What is the Bagolini striated glasses test/ how is it done and what are the results interpretation
Test to detect BSV/ ARC or suppression. Each lens has fine striations convert point source of light into line as with Maddox rod.
2 lenses placed at 45 degrees and 135 degrees infront of each eye and patient fixates on focal light source.
Results cant be interpreted unless it is known if strab present or not
If 2 streaks intersect at centres X - BSV present if eyes straight or harmonious ARC
If 2 lines seen but no cross- diplopia present
If 1 streak seen- no simultaneous perception and suppression present
If small gap present in one of the streaks, a central suppression scotoma (in microtropia) seen. Can confirm with a 4PD test
82
What is the 4PD test
distinguishes bifoveal fixation (normal BSV) from foveal suppression (also known as central suppression scotoma CSS). Microtropia employs principle in 20PD test to overcome diplopia
83
What are the results of the 4PD test in bifoveal fixation
prism placed base out (microtropia commonly esotropic not exotropic) infront of the right eye with deviation of image away from fovea temporally. Followed by corrective movement of both eyes to left. Left eye then converges to fuse the images
84
What are the results of the 4PD test in left microtropia
Patient fixates at distant target with both eyes open and 4PD placed base out infront of eye suspected CSS.
Image moved temporally in left eye but falls within CSS and no movement of either eye observed
Prism moved to right eye which adducts to maintain fixation. The left eye similarly moves to left consistent with Hering law of equal innervation but second image falls within CSS of left eye so no subsequent refixation is seen
85
How many grades of BSV can be graded on synoptophore
First (simultaneous perception SP)
Second (fusion)
Third (steropsis)
86
What is the Hirschberg test
rough objective estimate of angle of manifest straibismus- good for young/ uncooperative patients or when fixation in deviating eye is poor. Good test to exclude pseudostrabismus. Pen torch shone from arms length and patient asked to fixate light. Corneal reflection of light centered in pupil of fixating eye but decentered in squinting eye in direction opposite to deviation. Distance of light reflection from pupil noted. Each mm deviation is 7 degrees (1 degree is 2PD). eg
If reflex located at temporal border of pupil angle is 15, limbus 45
87
What is the Krimsky test
placement of prisms infront of fixating eye until corneal light reflections are symmetrical. Reduces problem of parallax and commonly used than prism reflection test
88
What is the prism reflection test
place prisms infront of deviating eye until corneal light reflections symmetrical
89
What are some tests to measure deviation
Hirschberg test
Krimsky
Prism reflection test
Cover- uncover test
Alternate cover test
Prism cover test
Maddox wing
Maddox rod
90
What is the cover test
detects heterotropia- begin near test using light to observe corneal reflections and assess fixation in deviating eye. Repeat for near using accommodative target and then for distance as follows:
look at straight ahead target
if right deviation suspected, examiner covers fixing left eye and notes any right eye movement to take up fixation. No movement is orthotropia or left exotropia. Adduction of right eye to take up fixation indicate right exotropia/ abduction, right esotropia
Downward movement indicate right hypertropia/ upward movement is right hypotropia. Repeat test on fellow eye
91
What is the uncover test
detects heterophoria. Performed for near (using accommodative target) and distance as follows
look ahead distance target, cover right eye and after 2-3 seconds removes cover. No movement is orthophoria. Normally very slight latent deviation in most normal people. If right eye had deviated under cover, a refixation movement is observed on being uncovered. Adduction of right eye indicates exophoria and abduction esophoria. Upward/ downward movement is vertical phoria. After cover removed, examiner notes speed and smoothness of recovery- strength of motor fusion. Repeat test fellow eye.
92
What is the alternate cover test and how is it done
induces dissociation to reveal total deviation when fusion disrupted. Performed only after cover- uncover test
Right eye occluded for several seconds
Occluder quickly lifted and shifted to left eye for 2 seconds then back and forth several times. Examiner notes speed and recovery smoothness as eyes return to pre dissociated state. Patient with well compensated heterophoria will have straight eyes before and after test performed whereas poor control will have manifest deviation
93
What is the prism cover test
measures the angle of deviation and includes alternate cover test with prisms. Performed with patient fixing on distant target in primary position then 8 gaze positions. Repeated in primary position with near fixation .
Prisms of increasing strength placed infront of one eye with base opposite to direction of deviation. Alternate cover test performed continuously as stronger prisms used using prism bar. Amplitude of refixation movement gradually decrease as strength of prism reaches extent of deviation
End point achieved when no movement seen. Can add more prism till reversal then reduced to find neutral value.
94
What is the Maddox wing test
dissociates the eyes for near fixation (1/3m) and measures heterophoria. Right eye only sees white vertical arrow and a red horizontal arrow. Left eye sees only horizontal and vertical rows of numbers.
Horizontal deviation measured by asking patient which number the white arrow points to. Amount of cyclophoria determined by asking the patient to move the red arrow so it is parallel with horizontal row of numbers.
95
What is the Maddox rod test
fused cylindrical red or white glass rods convert appearance of white light spot into red or white streak. Rod placed infront of right eye. Dissociates the two eyes: red streak seen by right eye cannot be fused by unaltered white spot of light seen by left eye. If red light intersect white dot- no horizontal phoria. if red vertical line to left of white dot- exophoria. If red vertical line to right of white dot -esophoria.
96
What is the double maddox rod test used for
determine cyclodeviation
97
When assessing ocular motility what is checked first, saccades or pursuits
pursuits followed by saccades
98
How are versions tested
versions towards 8 eccentric gaze positions are tested by asking the patient to follow a target usually pen/ torch (allows corneal light reflex assessment). Check versions and ductions first then perform cover tests as needed.
99
How are ductions tested
assessed if reduced ocular motility present in either/ both eyes. Pen torch used with careful attention to corneal reflex position. Fellow eye occluded and patient asked to follow the torch into various gaze poisitions.Numeric system used 0 denotes full movements and -1 to -4 to denote increasing degrees of underaction.
100
What is the -1 to -4 system of grading muscle underactions
using LR for instance
-4 denotes inability to abduct eye past midline
-3 inability to abduct the eye more than 22.5 degrees past the midline
-2 inability to abduct eye more than 45 degrees past the midline
-1 inability to abduct eye more than 67.5 degrees past the midline. In the same way, overactions are used +1 to +4
101
What is the near point of convergence
nearest point on which eye can maintain binocular fixation. measured with RAF ruler which rests on patients cheeks. Target is moved slowly towards patients face till one eye loses fixation and drifts laterally. Subjective NPC point where patient reports diplopia. Normally NPC nearer than 10cm without undue effort
102
What is the post operative diplopia test
simple test mandatory prior to strab surgery in all non binocular patients over 7-8 years to assess risk of diplopia post op
corrective prisms placed infront of one eye (deviating eye) patient asked to fixate ahead target both eyes open. Prisms slowly increased till angle overcorrected and patient reports if diplopia present. If suppression persists, little risk of diplopia post op. Diplopia may be intermittent or constant but in either case need to perform diagnostic botox test. Intractable diplopia difficult to treat
103
What are some methods to test the field of BSV
Goldmann Perimetry
Tangent screen
Hess chart
Measures about 45-50 degrees from the fixation point except when nose blocking.
104
What are the principles of the Hess chart in how it works
Hess screen contains tangent pattern displayed on dark grey background. Red lights that are individually illuminated by a control panel indicate cardinal gaze positions within central field (15 degrees from primary position) and a peripheral 30 degrees. Each square represents 5 degrees of ocular rotation. Eyes dissociated using reversible goggles incorporating red and green lens. Red infront of fixating eye and green lens non fixating eye. Red light points illuminated at selected positions on the screen. Patient holds a green pointer and asked to superimpose green light over each red light in turn. In orthophoria, 2 lights should be more or less superimposed in all gaze positions. Goggles reversed and process repeated
105
What is a Lees screen and how does it work
apparatus consists of 2 opalescent glass screens at right angles to each other bisected by 2 sided plane mirror dissociating each eye. Each eye can only see one of the 2 screens. Each screen has a tangent pattern only revealed when screen is illuminated. Patient faces non illuminated screen with chin on a rest. Using a pointer examiner indicates target point on illuminated tangent pattern and patient positions a pointer on the non illuminated screen. This is repeated for the fellow eye
106
What are some features on a Hess chart with a right lateral rectus paresis of recent onset
smaller chart- paretic muscle (right eye)
larger chart- overacting yoke muscle (left eye)
smaller chart shows greatest restriction in main direction of action of paretic muscle (RLR)
Larger chart shows greatest expansion in the main direction of action of yoke muscle LMR
Degree of disparity between plotted and template points in any gaze position gives an estimate of angle of deviation (each square 5 degrees)
107
What are some changes with time for example with Right SR palsy
Shows underaction of affected muscle with overaction of yoke muscle (LIO). Due to great incomitance of 2 charts diagnosis is easy. If paretic muscle recovers, both charts are then normal
Secondary contracture of ipsilateral antagonist (RIR) manifest as overaction leading to secondary inhibition of antagonist of yoke muscle LSO- shows on chart as underaction. May lead to appearance of LSO being primary paretic muscle. With time both charts become commitant making it difficult to determine the initial muscle weakness.
108
What does a left third nerve palsy pattern look like Hess chart
area under left chart smaller than right chart. Left exotropia, Left chart shows underaction of all muscles except lateral rectus. Right chart shows overaction of all muscles except the RMR/RIR (yokes of spared muscles)
109
What does a recently acquired Right fourth nerve palsy pattern look like Hess chart
right chart smaller than left
right chart shows underaction of SO/ overaction of IO
Left chart- overaction of IR + underaction of SR
110
What does a Congenital Right fourth nerve palsy pattern look like Hess chart
no difference in overall chart size
Right hypertropia
Hypertropia increases on laevoversion and reduces on dextroversion
Right chart shows underaction of SO + Overaction of IO
Left chart shows overaction of IR + underaction of SR
111
What does a right sixth nerve palsy pattern look like Hess chart
Right chart smaller than left
Right esotropia
Right chart shows marked underaction of lateral rectus. Left chart shows marked overaction of medial rectus
Inhibitional palsy of LLR not yet developed
112
What are the commonest reasons for strabismus
refractive error: hypermetropia, astigmatism, anisometropia, myopia
113
What is the follow up like for refraction in children with strabismus
as refraction changes with age, check at least once a year and more frequently in younger children and if VA is reduced.
114
How does hypermetropia change as the baby is young onwards
Birth- mostly hypermetropia
After 2- increased hypermetropia and decrease in astigmatism
2-6- hypermetropia may continue to increase until 6 years age
6-8 - hypermetropia levels off and then decreases
115
What is the thought about fully correcting hypermetropia in children
may reduce physiological emmetropization
116
In a child with hypermetropia- when is a prescription prescribed
upto 4D of hypermetropia should not be corrected in a child without squint unless they have near vision problems. If hypermetropia >4D, correct 2/3rds prescription. If esotropia present, full cycloplegic correction should be given even if <2 years old
117
In a child with astigmatism- when is a prescription prescribed
cylinder of 1.50D or more should be prescribed especially in anisometropia after 18 months
118
In a child with myopia- when is a prescription prescribed
depends on age of the child
under 2 (-5D or more corrected), between 2-4 (-3D corrected), Older children should have even low myopia corrected to allow clear distance vision. Undercorrection and bifocals may retard progression and under ix
119
In a child with anisometropia- when is a prescription prescribed
after 3 years age, full difference in refraction between eyes prescribed if more than 1D with full hypermetropic correction in squint
120
What is a positive angle kappa
normal fovea located temporal to anatomical axis of eye. So eyes slightly abducted to achieve bifoveal fixation + light shone on cornea cause reflex on cornea nasal to centre of both eyes. This is + angle kappa
121
What overall situations would cause a larger angle kappa
temporally displaced macula (pseudoexotropia)
122
What is a negative angle kappa and what conditions can cause this
when fovea nasal to posterior pole eg high myopia. Corneal reflex located temporal to corneal centre + may simulate esotropia
123
What is a heterophoria
when fusional amplitudes are insufficient to maintain alignment particularly at times of stress/ poor health
Both eso/exophoria can be classified at distance at which angle greater; convergence excess or weakness, divergence weakness and mixed
124
What is the treatment for heterophoria
orthoptic treatment most value in convergence weakness exophoria
any significant refractive error should be corrected
symptoms relief with temporary stick on Fresnel prisms (max 10-12 PD split between 2 eyes)
Surgery may be needed for larger deviations
125
What are some examples of vergence abnormalities
convergence insufficiency
divergence insufficiency and divergence paralysis
near reflex insufficiency
spasm of near reflex
126
What are the signs/ treatment of convergence insufficiency
remote NPC independent of any heterophoria + poor fusional convergence amplitudes
treat with orthoptic exercises aimed at normalizing near point + maximise fusional amplitudes. Good compliance can eliminate symptoms in few weeks but if persistent treated with base in prisms
127
What is accommodative insufficiency
may be idiopathic (primary) or post viral typically affecting school age children. Minimum reading correction to give clear vision prescribed but difficult to discard
128
What are the features of divergence insufficiency
part of common condition called sagging eye syndrome SES. occurs in elderly adults. if symmetrical age related distance esotropia (ARDE) results and if asymmetrical, unilateral hypotropia + excyclotropia results (cyclovertical strab)
129
What are the features of divergence paralysis
rare condition associated with underlying neurological disease like intracranial SOL, CVA, Head trauma. Can present at any age be difficult to distinguish from 6th nerve palsy. Primarily concomittant esodeviation with reduced/ absent divergence fusional amplitude. No other clinical or radiological features of SES. Prisms best option.
130
What is near reflex insufficiency
paresis of near reflex presents as dual convergence and accommodation insufficiency. Mydriasis may be seen on attempted near fixation. Treatment involves reading glasses, base in prisms and possibly botox. Difficult to eradicate.
Complete paralysis in which no convergence or accommodation can be initiated may be of functional origin due to mid brain disease or after head trauma, recovery is possible
131
What are some features of spasm of near reflex and how is it treated
functional condition affecting patients of all ages mainly females. Diplopia/ blurry vision/ headaches are presenting symptom
Signs- esotropia/ pseudomyopia/ miosis, spasm may be triggered when testing ocular movements, observation of miosis key to diagnosis, refraction with/ without cyclo confirms pseudomyopia which must not be corrected optically
Treat by reassurance and advising patient to discontinue activity which triggers response. If persistent, atropine + full reading correction prescribed.
132
What is a concomitant vs inconcomitant esotropia
Concomitant- variablity of angle of deviation is within 5PD in different horizontal gaze positions
Incomitant- angle differs in various gaze positions due to abnormal innervation/ restriction
133
What are some features of early onset esotropia
Defined as esotropia developing in first 6 months of life in normal infant with no refractive error/ limitation of eye movement.
Angle fairly large >30PD and stable
Fixation in most infants is alternating in primary position
Cross fixating in side gaze so child uses left eye in right gaze and right eye on left gaze. Can give false impression of bilateral 6th nerve palsy. Abduction can be demo by doll head manouevre or rotate child. Nystagmus horizontal. Asymmetric OKN, IO overaction may be present. DVD by 3 years in 80%
134
What is latent nystagmus
when one eye covered and fast phase beats towards side of fixing eye. Means direction of fast phase reverses according to which eye is covered
135
What is manifest latent nystagmus
same as latent nystagmus except nystagmus present with both eyes open but amplitude increases when one eye is covered
136
What is the differential diagnosis of esotropia
bilateral congenital 6th nerve palsy/ secondary esotropia due to organic eye disease/ nystagmus blockage syndrome where convergence dampens a horizontal nystagmus and mechanical imitations of eye movements like Duane/ Mobius syndrome
137
What is the timing of surgery for esotropia
after initial variability period, angle of esotropia becomes constant at 4-5 months age. Once amblyopia and significant refractive error addressed, eyes surgically aligned within 4 months of onset of constant esotropia. Leads to better sensory outcome and BSV
138
What is the initial procedure of choice for esotropia
recession of both MR muscle or unilateral MR muscle recession + LR resection. Angles >50PD require recession of both MR muscles + resection of 1 LR muscle
139
What should be done if the angle of esotropia is larger than 65PD (Surgery option)
recession of both MR muscle + resection of both LR muscles
140
What is the upper limit of MR recession and why
>6.5mm leads to late overcorrections
141
What is an acceptable post operative esotropia surgical outcome (in terms of PD)
Align eyes within 8PD associated with peripheral fusion and central suppression. Small angle residual strab stable even though bifoveal fusion not achieved
142
What are the options for treating undercorrection following esotropia surgery
further recession of MR, resection of 1 or both LR, or surgery to other eye depending on initial procedure
143
How to manage post esotropia surgery IO overaction
most commonly at 2 years age. Parents warned further surgery may be necessary despite initial good result. Initially unilateral becomes bilateral within 6 months. IO weakening procedures are disinsertion/ recession and myomectomy
144
What is DVD
updrift with excyclorotation (Extorsion of eye) when under cover or spontaneously during periods of visual inattention. When cover removed, eye moves downward without corresponding down drift of other eye. Usually bilateral. Surgical treatment for psychosocial reasons. Options are SR recession +/- posterior fixation sutures, resection or tuck IR muscle and IO anterior transposition
145
What percentage of patients undergoing esotropia surgery will develop amblyopia post op
50% as unilateral fixation preference develops post op
146
What are the 2 types of accommodative esotropia
refractive accommodative esotropia
non-refractive accommodative esotropia
147
What is refractive accommodative esotropia and what are the 2 types
AC/A ratio normal + esotropia physiological response to excessive hypermetropia between +2 and +7. Considerable degree of accommodation needed to focus clearly on even distant target accompanied by proportional convergence beyond patient's fusional divergence amplitude. Magnitude of deviation varies <10PD between distance and near. Deviation presents at 18 months to 3 years
- Fully accommodative or partially accommodative esotropia
148
What is fully accommodative esotropia
hypermetropia + esotropia when refractive error uncorrected. Deviation eliminated and BSC present after hypermetropia optically corrected.
149
What is partially accommodative esotropia
reduced but not fully eliminated by full correction of hypermetropia. Amblyopia is frequent as well as bilateral congenital superior oblique weakness. most cases show suppression of squinting eye although ARC may occur but of lower grade than microtropia
150
What is non refractive accommodative esotropia and what are the 2 types
AC/A ratio is high so that a unit increase of accommodation is accompanied by disproportionately large increase in convergence. Occurs independently of refractive error although hypermetropia frequently co-exists
Types are convergence excess, hypoaccommodative convergence excess
151
What is convergence excess non refractive accommodative esotropia
High AC/A ratio due to increased accommodative convergence (accommodation normal, convergence increased)
Normal near point accommodation/ straight eyes with BSV for distance/ esotropia for near/ usually with suppression/ straight eyes through bifocals
152
What is hypoaccommodative convergence excess non refractive accommodative esotropia
high AC/A ratio due to increased accommodation (accommodation is weak/ necessitating increased effort which produces over convergence)
Remote near point of accommodation
Straight eyes with BSV for distance
Esotropia for near/ usually with suppression
153
What is the refractive treatment for accommodative esotropia
correct refractive error initially- in <6 years full cycloplegic hypermetropic correction. At 8 years non cyclo refraction and max plus that can be tolerated (manifest hypermetropia) prescribed
Convergence excess eso- bifocals
Most satisfactory bifocals- executive type
Bifocals also used in hypoaccommodative esotropia where AC/A ratio is not overly excessive. Higher levels need surgery
154
What is the surgical treatment for accommodative esotropia
Surgery- only if specs dont control deviation and after every attempt made to treat amblyopia
Bilateral MR recessions where deviation for near > distance.
If no significant difference between near/ distance, equal vision bilaterally some perform unilateral MR recession + LR resection others prefer bilateral MR recessions
With residual amblyopia- surgery performed on amblyopic eye
Partially accommodative eso- surgery for improved appearance best delayed until child requests it
Usual first procedure for convergence excess eso is recession of both MR. Relies on fusion to prevent distance exo
Faden procedure for undercorrections after bimedial recessions
155
What is the Faden operation
MR posterior fixation sutures
156
What is a microtropia
small angle <10PD squint. Binocular cooperation in mircotropia more substantial than most manifest deviations. Also called monofixation syndrome. Can be primary/ secondary. Secondary is the sequelae to strabismus surgery/ other treatmetnts
157
What are some features of microtropia
Rare symptoms unless decompensating heterophoria
Small manifest angle of deviation may not be detectable on cover testing. Prominent association with anisometropia mainly hypermetropia/ hypermetropic astigmatism + amblyopia of ametropic eye. Normal motor fusion as shown by fusional amplitudes. ARC present with abnormal BSV. 4PD test is useful in assessment
158
What is the treatment for microtropia
correct refractive error and occlude for amblyopia as indicated. Aggressive treatment leads to normalization. Most patients remain stable and symptom free
159
What are the presentation/ signs and treatment for near esotropia (non accommodative convergence excess)
presents in older children/ young adults
Signs: no significant refractive error/ orthophoria or small esphoria with BSV for distance/ esotropia for near but normal or low AC/A ration/ normal near point of accommodation
Treat with bilateral MR recessions
160
What are the presentation/ signs and treatment for distance esotropia
presents in healthy young adults who are often myopia
Signs: intermittent/ constant esotropia for distance/ minimal or no deviation for near/normal bilateral abduction/ fusional divergence amplitudes may be reduced/ absence of neurological disease
Treat with prisms until spontaneous resolution or surgery in persistent cases
161
What are the presentation/ signs and treatment for acute (late onset) esotropia
presents at 5-6 years age
signs: sudden onset diplopia/esotropia. Normal ocular motility without significant refractive error. Underlying 6th nerve palsy must be excluded. Management: because onset of concomitant esotropia in older child may indicate underlying neurological disorder, check pupils, exclude ON changes, nystagmus and 6th nerve palsy. Neuroradiologic exam may be needed.
Treat: aimed at re-establishing BSV to prevent suppresion using prisms/ botox/ surgery
162
What are the features of secondary (sensory) esotropia
unilateral VA reduction interfering/ abolishes fusion. Causes are cataract/ optic atrophy or hypoplasia, macula scarring or retinoblastoma. Dilated fundus exam important
163
What is consecutive esotropia
follows surgical overcorrection of exodeviation. If occurs after surgery for intermittent exotropia in child it should not be allowed to persist for >6 weeks without further intervention
164
What is sagging eye syndrome
commonest causes of acquired strabismus in elderly non myopic individuals and occurs with blepharoptosis and deepening of superior sulcus. Condition arises due to age related degeneration of ligaments which interconnects the EOM. Results in bilateral inferior sagging of LR pulley, causing esotropia and/or cyclovertical malalignment
165
What are the symptoms and signs of sagging eye syndrome
symptoms: individual notices intermittent binocular diplopia in distance which becomes permanent over period of several months. Distance deviation rarely >10PD
Signs: distance esotropia/ with no near esotropia. Full horizontal ductions and clinically normal horizontal saccadic eye velocities, limited supraduction of both eyes, blepharoptosis, deep superior sulcus. If downward displacement of LR pulley asymmetrical, unilateral hypotropia with excyclotropia results
166
What is the treatment of sagging eye syndrome
conservative treatment for most with prism incorporated into distance spectacles as they d not have diplopia when doing near tasks. If surgery needed, resection/ plication of LR or recession of MR can be considered.
167
What is high myopia esotropia (heavy eye syndrome)
A cause of acquired esotropia in adults due to high myopia average 18D (range 12-21D) and AL 27-35mm. Due to shifting of LR and SR muscles secondary to elongated posterior portion of highly myopic eyeball. Imaging shows inferior shift of LR and nasal shift of IR/SR causing eye to shift superotemporally from pulley array converting LR from abductor to infraductor
168
What is high myopia esotropia (heavy eye syndrome)
present with diplopia associated with limitation of abduction/ elevation
169
What is the treatment for high myopia esotropia (heavy eye syndrome)
surgery involves loop myopexy, uniting adjacent borders of LR/ SR with non absorbable sutures. Condition responds poorly to LR tightening or MR alone
170
What is the presentation/ signs/ neurological anomalies/ treatment and Ddx for constant (Early onset) exotropia
presents at birth
signs: normal refraction/ large and constant angle/ DVD may be present
Neurological anomalies frequent in contrast with infantile esotropia
Treatment mainly surgical and consists of LR recession and MR resection
Ddx is secondary exotropia which may conceal serious ocular pathology
171
What are the presentation and signs of intermittent exotropia
2 years- with exophoria breaks down to exotropia under conditions of visual inattention, bright light (Resulting in reflex closure of affected eye), ill health or fatigue
signs: eyes are straight with BSV at times and manifest suppression at other times. Control of squint varies with fixation distance and other factors like concentration
172
What are the types of intermittent exotropia
Distance excess exotropia- angle of deviation greater for distance than near and increases further beyond 6m. Simulated and true forms recognized
Basic exotropia- control of squint and angle of deviation are same for distance and near fixation
Convergence insufficiency exotropia- deviation greater for near fixation. Occurs in older children and adults, associated with acquired myopia/ presbyopia
173
What is the difference between simulated and true distance excess exotropia
simulated: high AC/A ratio with tenacious proximal fusion. Distance angle initially seems larger than near angle but deviation for near and distance similar when near angle remeasured with patient looking through +3D lenses or after 30-60minutes of uniocular occlusion to relax TPF, latter with normal AC/A ratio
true: angle for near remains significantly less than for distance with above tests
174
What is the treatment for intermittent exotropia
spectacle correction- in myopic patients in some cases control deviation by stimulation accommodation and with it convergence. In some cases overminus prescriptions can be useful
Part time occlusion of non deviating eye may improve control in some and orthoptic exercises for near exotropia.
Effective and stable control of intermittent exotropia can be observed. Surgery for poor control or progressive deterioration. Unilateral LR/ MR resection preferred except in true distance exotropia when bilateral LR recessions more usual.
175
What is Duane retraction syndrome
failure of innervation of LR by hypoplastic 6th nerve nucleus with anomalous innervation of LR by fibres from 3rd nerve. Condition bilateral. Upto half patients have associated systemic defects like deafness/ external ear anommalies/ speech and skeletal problems. Associated mutations in several genes found. 10% cases familial
176
What are the clinical features of duane retraction syndrome
face turn typical confers BSV with the face in turned position avoiding amblyopia
complete/partial restriction of abduction
restricted adduction usually partial
retraction of globe on adduction due to contraction of mR/LR with narrowing of palpebral fissure
upshoot/ down shoot in adduction may be present. In some, produced by tight LR muscle slipping over or under globe to produce anomalous vertical movement
deficiency of convergence where affected eye remains fixed in primary position while unaffected eye converging
177
What are the 3 types of Huber classification for duane retraction syndrome
1- commonest: limited or absent abduction/ normal or mild limited adduction/ in primary position straight or slight esotropia
2- least common: limited adduction/ normal or mild limited abduction/ primary position straight or slight exotropia
3- limited adduction/ abduction, primary position straight or slight esotropia, in some cases phenotypic variants allied to differing genotypes
178
What is the treatment for duane retraction syndrome
majority dont need surgery
most young children maintain BSV using CHP to compensate for LR weakness and surgery needed only if loss of BSV. This may be indicated by failure to use CHP. In adults/ children >8 surgery can be done to reduce CHP which is socially unacceptable or causing neck discomfort. Amblyopia when present is due to anisometropia rather than strabismus. Unilateral/ bilateral +/- LR recessions are procedure of choice. In order to improve abduction/ transposition of SR/ IR muscles to LR may be required. LR of involved side should not be resected as increases retraction
179
What is mobius syndrome
rare usually sporadic condition. Components are congenital non progressive bilateral 6th and 7th nerve palsies believed to relate to developmental abnormality of brainstem
180
What are the systemic and ocular features of Mobius syndrome
Systemic: bilateral facial nerve palsy asymmetrical and often incomplete giving rise to expressionless facial appearance and problems with eyelid closure. 5th/8th/10th/12th CN may be affected. Limb anomalies and mental handicap may be present
Ocular: bilateral 6th nerve palsy, horizontal gaze palsy (50%), occasionally 3rd/4th nerve palsy + ptosis
181
What is Brown syndrome
condition involving mechanical restriction, typically of SO tendon. Congenital but can be acquired. Recent evidence suggests at least some congenital cases categorized as CCCD
182
What are the causes of congenital vs acquired Brown syndrome
congenital: idiopathic/ congenital click syndrome- impaired movement of SO tendon through trochlea
Acquired: trauma to trochlea or SO tendon/ Inflammation of tendon which may be caused by RA/ Pansinusitis/ scleritis
183
What are the 3 types of Brown syndrome
ALL HAVE LIMITED ELEVATION IN ADDUCTION
Mild- no hypotropia in primary position/ no down shoot in adduction
moderate- no hypotropia in primary position. Down shoot in adduction
Severe- hypotropia in primary position/ down shoot in adduction/ chin up head posture/ face turn away from affected eye
184
What is the treatment for congenital and acquired brown syndrome
congenital: doesnt usually require treatment as long as BSV maintained with acceptable head posture. Spontaneous improvement seen by end of first decade. Indications for treatment are significant primary position hypotropia/ deteriorating control/ unacceptable head posture. Recommended procedure is lengthening of SO tendon
Acquired: treatable aetiology addressed specificially. Depending on cause may benefit from steroids either orally/ injected near the trochlea
185
What are alphabet A and V patterns
V/A patterns occur when relative contributions of SR/ IO to elevation or IR/SO to depression are abnormal resulting in derangement of balance of horizontal vectors in up and downgae. Also be caused by anomalies in position of rectus muscle pulleys. Assessment by measuring horizontal deviations in primary positions/ upgaze and downgaze. They can occur in both concomitant and incomittant deviations
186
What is a V pattern
significant when difference between upgaze and downgaze is >15PD
187
What are the causes of V pattern
IO overaction associated with 4th nerve palsy. SO underaction with IO overaction seen in infantile esotropia + other childhood esotropias. Eyes straight in upgaze with marked esodeviation in downgaze
SR underaction/ Brown syndrome/ Cranofacial anomalies with shallow orbits + downslanting palpebral fissures
188
What is the treatment for V pattern exo/eso deviations
IO weakening or SO strengthening when oblique dysfunction present. Without oblique dysfunction treatment is
V pattern esotropia- bilateral MR recessions + downward transposition of tendons
V pattern exotropia- bilateral LR recessions + upward transpositions of the tendons
189
What is an A pattern
considered significant if difference between upgaze and downgaze is >10PD. Particular complaint may be difficulty with reading if patient binocular
190
What are the causes of A patterns
Primary SO overaction associated with exodeviation in primary gaze position/ IO underaction/ palsy with subsequent SO overaction/ IR underaction
191
What is the treatment for A pattern
patients with oblique dysfunction treated by SO posterior tenotomy which will correct 20PD of A pattern. Total tenotomy correct upto 50PD of A pattern. Treatment of cases without oblique muscle dysfunction is
A pattern esotropia- bilateral MR recessions + upward transpositions of the tendons
A pattern exotropia- bilateral LR recessions + downward transpositions of tendons
192
What are the aims of surgery in strabismus and what are the 3 types of procedures done
correct misalignment/ improve appearance and restore BSV. First correct refractive error and/ or amblyopia then once max visual potential present residual deviation treated surgically. 3 main types of procedures are
strengthening to enhance pull of muscle/ weakening to decrease strength of action of muscle/ vector adjustment procedures which have the primary aim of altering direction of muscle action
193
What are some examples of muscle strengthening procedures
Resection- shorten muscle enhance effective pull. Suitable for rectus muscle.
Plication (tucking) similar effect to resection but less traumatic and does not sacrifice anterior ciliary vessels and can be reversed if needed. Used to tighten a lax SO muscle in congenital 4th nerve palsy
Advancement of muscle nearer to limbus to enhance action of previously recessed rectus muscle
194
What are some examples of muscle weakening procedures
Rectus muscle recession
IO recession
Disinsertion- myomectomy detaching a muscle from insertion without reattachment for weakening overacting IO muscle
Posterior fixation suture (Faden procedure)- suture muscle belly to sclera posteriorly to decrease pull of muscle in field of action without affecting eye in primary position. May be used on MR to reduce convergence in convergence excess esotropia and on SR to treat DVD. In DVD SR may also be recessed
195
What is muscle transpositioning surgery
relocation of 1 or more EOM to substitute for action of absent/ severley deficient muscle. Most common indication is severe LR weakness due to acquired 6th nerve palsy. Other uses are CCCD like Duane, alphabet patterns, monocular elevation deficit
196
What are some operative complications of strabismus surgery
lost/ slipped muscle especially MR muscle
Globe perforation by misplaced suture in high myopia within thin sclera
Opening of posterior tenon capsule leads to fibrosis involving fat and EOM (especially when operating on IO muscle)
197
What are some post operative complications of strabismus surgery
over correction/ under correction common and after observation period to obtain stable measurements reoperation may be needed
Anterior segment ischaemia in older patients with systemic vascular disease but rare. Can be avoided by not removing >2 muscles per eye at one time
Stretched scar can occur years after initial surgery resulting in malalignment needing further surgery
198
When is the effect of botox on a muscle max and when does it wear ooff
topical anaesthetic + EMG
effect takes several days max at 1-2 weeks after injection and wears off by 3 months.
199
What impact does botox have on an EOM and what are the side effects
Lengthens EOM which it is in injected into and antagonist contracts.
Side effect: ptosis in 16% adults and 25% children
200
What are the indications for botox in strabismus
post op small angle residual strab (2-8 weeks post op)/
Correct infantile esotropia/
Active thyroid ophthalmopathy/
Determine risk of post operative diplopia/
Assess BSV potential/
LR palsy/ patients with psychosocially unacceptable deviation
201
Part 2
flashcards
Decks in class (20)
# Cards
-
Exam Techniques68
-
Eyelids183
-
Lacrimal Drainage System41
-
Orbit167
-
Dry Eye34
-
Conjunctiva80
-
Cornea183
-
Corneal and Refractive Surgery49
-
Episclera and Sclera35
-
Lens101
-
Glaucoma236
-
Uveitis191
-
Retinal Vascular Disease147
-
Acquired Macula Disorders163
-
Inherited Retinal Degenerations127
-
Retinal Detachment99
-
Vitreous Opacities10
-
Strabismus201
-
Neuro-ophthalmology352
-
Ocular Tumours164
