class test Flashcards
what are the symptoms of strabismus
diplopia (horizontal/vertical, binocular or monocular, can they make things single? anything make it worse?)
Awareness (deviation, some say it alternates)
pain (on motility and convergence)
headaches (where, when, lots of close work?)
asthenopia (eye strain, sore red eyes)
blurred vision
what anatomical factors can make px look as though they are squinting
epicanthus
lid anomalies
globe position
orbit and facial asymmetry
pupillary anomalies
iris anomalies
what tests would you use to test a baby’s vision (0-18 months)
forced choice preferential looking (FCPL)
Keeler or teller acuity cards
(cards with black & white stripes on right or left side)
cardiff acuity cards
what tests would you use to test a toddlers vision (18months - 3 years)
kays picture test
- single kay picture logMar
- kay picture crowded logMAR
what tests would you use to test a preschoolers vision
LogMAR crowded acuity test
(0.100 in crLogMAR = 0.200 in kays)
Sonsken
what vision tests should be use for each age group?
Age Vision Test
Birth-6mo Pref Looking
1-2 years Cardiff Cards
2-3 years Kay Pictures Single
3-4 years Kay Pictures Crowded
4-8 years Cr LogMAR
8+ years LogMAR Chart
what is the process called which the refractive state of the eye changes?
emmetropization
what are the classifications of amblyopia?
funtional type (improvement after treatment is expected)
- strabismic
- anisometropic
- stimulus deprivation
- meridional
- ametropic
- organic: toxic - may be reversible or irreversible
what management is there for amblyopia?
- refractive adaptation (full correction for full time wear)
- occlusion treatment
- (mod amblyopia 0.300-
0.600 begin w 2 hours, no
significant improvement-
increase to 6) - severe amblyopia (0.700 or worse) FT - all waking hours or part-time - set hours per day (6 is recommended)
- (mod amblyopia 0.300-
Atropine penalisation
Optical penalisation (rx manipulated to blur vision in better seeing eye to encourage use of amblyopic eye)
what are risks of occlusion
- strabismic amblyopia
- higher risk in older children
- sbisa bar ( density of suppression) must be assessed throughout treatment
amblyopia develops in other eye (rare in PT occlusion)
dissociation in decomponsating strabismus
allergic reaction
- skin reaction to patch
- allergy to atropine
what are the characteristics of BV
fusion
Retinal Rivalry
Stereopsis
Physiological diplopia
what is sensory fusion
the ability to perceive 2 similar images - one formed on each retina and interpret them as 1
what is motor fusion
the ability to maintain sensory fusion through a range of vergence movements
what are signs and symptoms of visual stress/ dyslexia
visual processing deficits
Visual perception and spatial confusion deficits:
perceiving letters and words as reversed forms (“seeing” b as d or was as saw); general spatial orientation problems.
Imperfect representation of letters, spelling patterns, and whole words and poor memory for visual detail. Template matching
symptoms of visual stress
moving words on page
jumbling words
poor convergence
poor accommodation
diplopia
asthenopia
headaches mostly frontal
skipping words on page
losing place frequently
what can help with visual stress
coloured overlays
long term = lenses and can be assessed on colorimeter
what is normal bsv
temporal retina projects to nasal space
nasal retina projects to temporal space
fixation is normal/straight
what is a convergence excess esophoria
deviation 10^ greater at near fixation
what is a divergence weakness esophoria
deviation 10^ greater at distance fixation
what is a non specific esophoria
deviation similar at near and distance fixation
what is a convergence weakness EXOphoria
Deviation 10^ greater at near fixation
what is a divergence excess exophoria
Deviation 10^ greater at distance fixation
what is a non specific exophoria
deviation similar at near and distance fixation
what is a concomitant strabismus
the dissociated deviation remains the same whichever eye is made to fixate - no significant change in the 9 positions of gaze
what is incomitant strabismus
dissociated deviation changes size depending which eye fixates
dissociated deviation changes size when the eyes are moved in different positions of gaze
what are the characteristics of infantile esotropia
- Onset < 6/12
- Large up to 45^
- Constant angle of deviation
- Cross fixates
- Usually alternating due to equal VA
- Not Accommodative as no significant refractive error
- Associated with Dissociated
Vertical Divergence (DVD)
and latent nystagmus
that develops 12-18mths
characteristics of intermittent esotropia
only present under certain conditions
px have NRC, hypermetropia and high AC/A ratio
e.g. with accom element, fully accom, conv excess
describe the two types of ARC
harmonious ARC
- angle on anomaly is equal to the angle of strabismus
Unharmonious
- angle of anomaly is greater than 0 but less than deviation
ARC characteristics
occurs in long standing deviation
small angle deviation <20^
usually convergent
mild amblyopia
rare in XT
provides useful bsv in manifest strabmismus
microtropia characteristics
small angle <10^ with ARC
common
stable
anisometropia
always mildly amblyopic (one line at least)
central suppression
good but not perfect BSV
strong motor fusion
what is microtropia WITH identity
no movement on CT
only diagnose with fixation ophthalmoscope and 4^ test
ARC and eccentric fixation at same retinal point
microptropia WITHOUT identity
Small manifest deviation
Less than 10^
Mostly Esotropia but can be exotropia
Microtropia without identity with latent component
Manifest deviation will increase on continued dissociation
Must measure manifest component with simulated PCT
Measure Latent Component with full PCT
What 4 parts does the visual function consist of
light sense
form sense
Color sense
Motion sense
what are the purpose of rods and cones
rods - movement and light
Cones - colour and central vision
what does it mean when a deviation is
a) compensated
b) decomponsating
c) decomponsated
Compensated - well controlled
Decompensating = poorly controlled
Decompensated = broken down to manifest deviation
what is a cyclical intermittent esotropia
ET at near and distance at regular intervals
what is a consecutive esotropia
when px was previously XT/XP
what factors can cause a constant esotropia with accom element
refractive - ET increases on accom, rx reduces size of deviation but doesnt eliminate
high AC/A ratio
ET = N>D, reduced with +3.00DS but not eliminated
what are the characteristics for a constant ET with accom element
onset gradual - 1-3years
hypermetropia
anisometropia
angle reduces with correction
amblyopia
poor BSV potential - suppression, possible ARC
o/a OF MUSCLES
what is the difference between a true and simulated near exotropia
true - uniocular occlusion, no change in deviation
simulated - occlusion increases distance angle
what is a residual esotropia
esotropia persists after surgery for a larger angle esotropia
EARLY ONSET ET CHARACTERISTICS
onset = 6mo - 2years
N=D
Amblyopia common
poor bsv prognosis despite age of onset
Deviation may increase with time
Sx management often needed
Late onset ET characteristics
onset = 2-8 years
N=D
intermittent - constant large angle
diplopia
NRC
OM normal
Minor injury or short period of uniocular occlusion preceding the onset
Esotropia acquired with myopia characteristics
gradual onset
progressive myopia (high -)
ET D>N
vertical deviation
seen on CT/MRI
Long eyes and older px
restricted elevation
marked abduction limitation
What is a secondary ET and what can cause it
Visual loss so severe that fusion is disrupted
due to trauma, retinal detachment or cataract
characteristics of secondary ET
VA loss often unilateral
Age of loss determines deviation
- after birth = ET/ XT
- childhood = ET
- Late childhood/ adult = XT
intractable diplopia
Large angle
what is a consecutive ET
Px with previous Hx of XT
causes of fully accom ET
refractive
High AC/A - conv excess
characteristics of conv excess ET
Onset 2-5 years
Hypermetropia – +1.50-+5.00DS
Int ET to an accommodative target
Esotropia on near fixation even with full +
BSV in distance when corrected
ET N>D sgls
High AC/A ratio: often 8:1 or more
Monocular eye closure seen
Equal VA (generally)
Suppression at N when ET
what is an intermittent cyclical ET
ET at near and distance at regular intervals
what is a primary decomponsated microtropia
micro increased in size
uncorrected +
High AC/A
What is a secondary microtropia
originally large angle tropia
angle reduced to microtropia
surgery
exercises
Optical treatment
what is a primary microtropia
microtropia is the initial defect
how to investigate central suppression in microtropia
bagolini
macular worth ligjts
polaroid 4 dot test
4^ prism test
fixation - visuoscope/ direct ophthalmoscope
what management options is there for microtropia
aim to maintain best possible VA
- refractive error
- treat amblyopia
- treat associated strab
- occlude fellow eye
what type of diplopia comes with right exotropia
Heteronymous (crossed) diplopia coming from an uncrossed eye
The image from an exotropic eye is seen on the opposite side
what is a true and simulated intermittent distance XT
true - no change to angle after occlusion or on accommodation
fusion - near angle increases after occlusion - normal AC/A
Accommodation - near angle increases w accom - high AC/A
characteristics of Int dist XT
Onset >6mo
Females>males
Better control at near
Suppression when manifest,
sometimes panoramic vision
Manipulation of accommodation and/ or vergence to control
Natural history variable
Manifest - inattention, poor GH, fatigue, alcohol, bright lights
how would you know if the deviation is true or simulated int dist XT
mono occlusion ->
NEAR=DISTANCE ANGLE = SIMULATED DIST XT, NORMAL AC/A (FUSION)
NO CHANGE IN ANGLE ->
MEASURE NEAR ANGLE W +3.00
-> no change = true int dist xt
N=D -> Simulated dist XT w high AC/A (accom)
what are the management options for Int Dist XT
refractive corection
orth exercises
alt occlusion
teach anti suppression (ONLY IF NRC)
concave lenses
prisms
tinted gls
Intermittent neart XT
This is when a patient has an exotropia at near and BSV in the distance. The angle of the deviation at near is 10^ > at near than distance.
- It can be true meaning that the angle stays the same after uniocular occlusion or
it can be simulated meaning the distance angle increases to equal the near angle after uniocular occlusion
. A simulated near exotropia is rarely seen.
- The characteristics of a true near exotropia include asthenopic symptoms such as ocular fatigue discomfort, watering and headaches.
- The patient usually has equal VA but may complain of diplopia.
- They are seen to have poor binocular convergence, NRC ad normal sensory fusion but have reduced positive motor fusion amplitude.
investigation for int dist XT
ORDER OF TESTING IS IMPORTANT
- Case history - VA- equal - CT (far distance) FD>D>N - Conv - Bagolini - PFR - Stereoacuity - N&D - AC/A- measured in distance - CBA - over accommodate to control so VA reduced - PCT - OM - Lateral incomitance/ A+V patterns - Diagnostic occlusion - Control Score
primary constant exotropia
Exotropia is the initial defect
Early onset
- Onset < 12 months = infantile XT
Decompensated intermittent exotropia
- Distance or non specific XT decompensation
Decompensated Intermittent XT
Aetiology
Characteristics
- Onset after 12mo of age - Hx of previously straight (photos) - Constant unilateral XT - Equal VA - amblyopia implies early - Suppression - no diplopia - NRC or ARC - difficult to determine - BSV - difficult to demonstrate - BSV potential post sx - excellent
Investigations
→ Case history - old photos, monoc closure → VA → CT (moderate angle, all distances) → BSV - retinal disparity the strongest stimulus to vergence in exotropes → Potential for BSV - Age - VA (prognosis for fusion) - Prism adaptation - BtxA
Differential diagnosis
Careful assessment needed…
- Make sure it’s not a constant exotropia with dense amblyopia, and not a secondary exotropia
secondary XT
Sensory
- Visual loss so severe that fusion is disrupted
- Age of visual loss determines the deviation
Shortly after birth pathology = ET or XT In childhood = ET Later childhood and adulthood = XT (more common)
Aetiology
Congenital or acquired vision loss
Reversible or irreversible
Characteristics
→ Gradual onset if acquired as adult - dip less → Large angle → Hx of unilateral VA loss → Age of visual loss determines deviation - Shortly after birth = ET or XT - Later childhood/adulthood = XT (more common)
Investigation
- Case history - Full OE - VA - If aphakic, assess VA potential with refraction corrected - BTxA - as prognosis investigation - Area and density of suppression - PCT (synoptophore, Prism reflection test)
Consecutive Exotropia
Px with previous hx of esotropia
Aetiology
Spontaneous
- Weak or absent vision
- Early onset ET, hypermetropia >5DS, amblyopia
- Gradual onset, dip
Result of surgical correction
Planned
- Primary ET c gd bsv potential
- Px with poor bsv potential - best left slightly, more stable long term result
Unplanned - most
- Early - slipped muscle
- Late - lack of binocular reflex
Characteristics
Result of surgical correction
Unplanned- most
Early - possible slipped muscle, inacurate surgery
- Diplopia
- Monoc closure (bright light)
- Limitation of adduction
- presentation 20-30y/o
- large XT (45^BI) - older larger
residual XT
XT persists after surgery for larger angle
planned
- int XT/ decom x - overcorrection poorly tolerated
- diplopia if fully corrected
- two stage surgery fro large angle
unplanned
- concave lenses (smaller angles)
- BTxA into recessed LR
- BI fresnel prism
- further surgery
Essential Infantile Esotropia
Aetiology
Generally unknown - multifactorial
Characteristics
Stable ET >30BO (some increase in size)
N=D angle
No sig refractive error, makes no difference
Onset <6mo,generally 3-4mo
Alternating - dense amblyopia rare (amblyopia in 41-35% chance post surgery)
Cross fixation - bilateral abduction limitation
Poor BSV prognosis
LMLN - intensity increases on occlusion - possible rotary component
DVD - >2 yrs old
IO o/a
Asymmetric motion VEPs
Asymmetry of OKN (N-T abnormal)
AHP
- Compensate for nystagmus
- Compensate abduction limitation
- Compensate for DVD (tilt)
Investigation
Case history - when did parents start noticing squint first
Refraction
VA
CR
CT
Prism reflections/ Krimsky/ PCT
Conv
OM
Dolls head test
Spinning baby test
OKN - binoc then monoc, both horiz directions
Dissociated Vertical Deviation (DVD)
- An anomaly which occurs on dissociation
Aetiology
- Unknown
- Thought to be related to disruption of binoc function
High incidence of latent nystagmus (as high as 100%)
Associated with infantile ET - can occur with other constant and intermittent deviations
Characteristics
Progressive elevation of the eye under the cover
Extorsion and latent nystagmus may be associated features
Fixation required
After onset of strab and nystagmus >2 y/o
After surgery for ET
Nearly always bilateral - can be very asymmetric, > in distance
Unsightly hypertropia - inattention or poor health/ fatigue
Elevation similar on ab- and ad- duction - can be spontaneous on versions(nose) - looks like IO o/a
AHP - tilt to side of fixing eye
A patterns more common
SO o/a possible
BSV weak if present at all
Investigation
- measurement is difficult
- manifest component measured with spct first
- Alt pct - each eye fixing to record asymmetry
- may be impossible to reverse movement
- can use synoptophore
reversed fixation test - differentiate between DVD and hypertropia
Bielchowsky darkening wedge test
Management
Persistent and frequent spontaneous elevation, intervention not often required
NON SURGICAL
Suggestion of manipulating rx to make fix with most affected eye
surgical - depends on
- associated IO O/A
- DVD unilateral or bilateral
- amount of asymmetry
- a-pattern with o/a SO
Nystagmus Blockage syndrome
Esotropia that results from use of conv to block/ abolish manifest nystagmus and improve VA
emmetropization
the process by which the refractive state of the eye changes is emmetropization
governed by active and passive factors
passive - refers to normal eye growth as eye increases, the power of the optical components decrease proportionally reducing refractive error and maintaining emmetropia
active - describes a visual feedback mechanism in the control of eye growth (visual experience)
he hyperopic element increases during the first six months
before any reduction towards emmetropia becomes apparent
- a significant reduction in the degree of astigmatism occurs in the infants first year (? until 18 to 48 months) result of increase in eye size, concurrent flattening of cornea
nfants have some ability to accommodate to objects at different distance at 2 weeks of age, this ability increases during the first 3 months
- cues to accommodation include blur, vergence, chromatic aberration and disparity ? which are used by infants
- need for infants to accommodate is much less( depth of focus as a result of a smaller pupil and visual acuity )
- the fact they do not make large accommodative efforts is related to lack of need, as much as lack of ability
strabismus definition
condition in which the visual axes deviate from bi foveal fixation when fusion is absent or suspended
characteristics of incomitant heterophoria
neurogenic
- angle increased when eyes turned in direction of affected muscle and decreases when turned away
mechanical
- opposite of neurogenic
myogenic
what is a primary constant exotropia
exotropia is the initial defect and present under all conditions
- early onset
- <12 months = infantile XT
near esotropia characteristics
onset 2-3 years
orthophoria at distance with bsv
ET at near
no sig refraction
equal va
normal ac/a
normal accom
bsv at near when ET neutralised
no change to ET with +
types of diplopia
homonymous (uncrossed)
- distant object will double when fixating on nearer object - eso deviations
- the image of the fixating object is received on the nasal retina of the deviating eye and is therefore projected temporally it results when non-corresponding retinal points are stimulated by the same object
Heteronymous (crossed)
- nearer object will double when distant object is fixated - exo deviations
- in which the image of the fixating object is received on the temporal retina of the deviating eye and is therefore projected nasally it results when non-corresponding retinal points are stimulated by the same object
what tests can you use to check for central suppression
bagolini
macular worth lights
polaroid 4 dot test
4^ prism test
Fixation - visuoscope/ direct ophthalmoscope
intermittent near exotropia characteristics
XT at near X in distance with bsv
asthenopic symptoms - ocular fatique, discomofrt, watering, headaches
diplopia
equal VA
poor binoc conv
NRC
Normal sensory fusion
Reduced positive motor fusion amplitude
intermittent distance XT
Characteristics
Onset >6mo
Females>males
Better control at near
Suppression when manifest, sometimes panoramic vision
Manipulation of accommodation and/ or vergence to control
Natural history variable
Manifest - inattention, poor GH, fatigue, alcohol, bright lights
Investigation - aim to assess control
ORDER OF TESTING IS IMPORTANT
- Case history - VA- equal - CT (far distance) FD>D>N - Conv - Bagolini - PFR - Stereoacuity - N&D - AC/A- measured in distance - CBA - over accommodate to control so VA reduced - PCT - OM - Lateral incomitance/ A+V patterns - Diagnostic occlusion - Control Score
characteristics of primary constant XT
- Onset after 12mo of age
- Hx of previously straight (photos)
- Constant unilateral XT
- Equal VA - amblyopia implies early
- Suppression - no diplopia
- NRC or ARC - difficult to determine
- BSV - difficult to demonstrate
- BSV potential post sx - excellent
consecutive exotropia
Px with previous hx of esotropia
Aetiology
Spontaneous
- Weak or absent vision
- Early onset ET, hypermetropia >5DS, amblyopia
- Gradual onset, dip
Result of surgical correction
Planned
- Primary ET c gd bsv potential
- Px with poor bsv potential - best left slightly, more stable long term result
Unplanned - most
- Early - slipped muscle
- Late - lack of binocular reflex
Characteristics
Result of surgical correction
Unplanned- most
Early - possible slipped muscle, inacurate surgery
- Diplopia
- Monoc closure (bright light)
- Limitation of adduction
- presentation 20-30y/o
- large XT (45^BI) - older larger
investigation for infantile strab
Case history - when did parents start noticing squint first
Refraction
VA
CR
CT
Prism reflections/ Krimsky/ PCT
Conv
OM
Dolls head test - checks vestibular ocular reflex
Spinning baby test
OKN - binoc then monoc, both horiz directions
DVD
- An anomaly which occurs on dissociation
Aetiology
- Unknown
- Thought to be related to disruption of binoc function
High incidence of latent nystagmus (as high as 100%)
Associated with infantile ET - can occur with other constant and intermittent deviations
Characteristics
Progressive elevation of the eye under the cover
Extorsion and latent nystagmus may be associated features
Fixation required
After onset of strab and nystagmus >2 y/o
After surgery for ET
Nearly always bilateral - can be very asymmetric, > in distance
Unsightly hypertropia - inattention or poor health/ fatigue
Elevation similar on ab- and ad- duction - can be spontaneous on versions(nose) - looks like IO o/a
AHP - tilt to side of fixing eye
A patterns more common
SO o/a possible
BSV weak if present at all
infantile strabismus management
Persistent and frequent spontaneous elevation, intervention not often required
NON SURGICAL
Suggestion of manipulating rx to make fix with most affected eye
surgery - bilateral MR recession
what is convergence insufficiency
Definition: Near point of convergence is less than 10cm.
Convergence can only by maintained at this distance with effort.
Can primary or secondary.
Highly treatable.
Primary: No other causes for convergence insufficiency are present, including heterophoria
aetiology of primary CI
Pre-disposing Factors:
Large interpupillary distance
Large periods of time only using distance fixation e.g., occupation
Precipitating Factors:
Fatigue from long periods of close work with/without poor lighting
Illness
Age
Medication/recreational drugs
Pregnancy
symptoms of CI
Patient often reports difficulty with reading or doing close work.
Intermittent diplopia during near work.
Blurred vision during near work.
Frontal headache.
Eyestrain.
Difficulty concentrating.
Movement of print.
investigation of CI
Case History
Distance and Near Vision
Cover Test and Angle of Deviation
Assessment of Convergence
Accommodation
Fusional Amplitude
treatment for CI
Correction of Refractive Error
Orthoptic Exercises
Convergence Exercises:
Smooth and Jump convergence
Smooth convergence: Pen to nose exercises
Jump convergence: Dot card
Base in Prisms:
Correct near exotropia
what is Convergence Paralysis
The ability to converge is completely lost.
May be primary or secondary.
Primary:
No previous history.
Investigation rules out other secondary causes.
Secondary:
Head Trauma
Neurological cause e.g., Parinauds syndrome, encephalitis, multiple sclerosis.
characteristics of convergence paralysis
Diplopia for all distances nearer than infinity.
Exotropia at near.
Ocular motility is normal in primary convergence paralysis.
Accommodation may or not be impacted.
Management of Convergence Paralysis
Once secondary convergence palsy is ruled out/underlying cause is investigated…
Conservative management:
Base in prisms to correct exo deviation.
Occlusion to prevent diplopia.
If accommodation is impacted, hypermetropic prescription in combination with base in prisms.
Botox to lateral rectus may be temporary fix
Convergence Spasm
Excessive convergence.
May also be associated with accommodation spasm.
Transient episodes of convergence.
Needs to be differentiated fromother causes of esotropia e.g., sixth nerve palsy.
Convergence Spasm will demonstrate:
Full ocular motility- full abduction.
Pupil miosis when convergence.
Dolls head- full eye movement.
Patients with convergence spasm may be suffering from significant stress in other aspects of their life.
Spasm may be exacerbated with testing- not seen when simply chatting to patient about other things.
Management: Reassurance and relaxation techniques.
Cycloplegic drops and plus lenses may be useful in short term.
