Esotropia - investigation and managment - Miriam Flashcards
what are the 3 main types of esotropia?
primary secondary and consecutive
what is a consectutive SOT?
previously XOT –> SOT
what is the most likely cause for consecutive SOT?
XOT surgery - left slightly exo to guard against post-operative drift towards XOT (commonly seen)
what is secondary SOT also called?
sensory SOT
what is a secondary SOT?
due to pathology (e.g. corneal opacity) and accommodation active therefore SOT
what is a constant SOT?
there is a tropia everywhere
what is an intermittent SOT?
SOT in some places, and phoria in some places
when does a constant SOT with an accommodative element decrease in size?
with hyperopic rx
in the distance
what is a partially accommodative SOT?
after hyperopic correction, the tropia reduces in size but stays manifest
what is partially accommodative SOT also known as?
constant SOT with accommodative element
is amblyopia common with a partially accommodative element?
YES - it is constant
when does infantile SOT occur?
before 6 months
what happens in infantile SOT? (in terms of vision)
cross fixation
what is cross fixation?
use of the right eye to view the left visual field and the use of the left eye to view the right visual field
what is an approx size of infantile SOT?
30 D or more
is amblyopia common in infantile SOT?
no UNTIL surgery
why is amblyopia not common in infantile SOT until surgery?
usually an alternating SOT until surgery, then become constant unilateral with amblyopia
what are 2 things you should look for in someone with infantile SOT?
DVD and MLN
what is DVD and MLN?
dissociated vertical divergence
manifest latent nystagmus
when does dissociated vertical divergence present?
before 2 years
what happens with dissociated vertical divergence?
eye drifts upwards spontaneously (day dreaming like anisha)or after being covered
which eye does a DVD occur in?
both but is asymmetric (therefore greater in one eye than the other)
features of manifest latent nystagmus
amplitude increases on dissociaton and on aBduction
THEREFORE vision better on aDduction
clinically may not be able to see manifest component
what does the ‘manifest’ part of MLN mean?
nystagmus is present with both eyes open
what does the ‘latent’ part of MLN mean?
amplitude increased when eyes abducted outwards / or covered
which way does the patient’s face turn to reduce nystagmus?
towards the fixing eye (to ADDUCT it) bc of cross fixation
which way will the OKN response be weak? in infantile SOT
nasal to temporal
in infantile SOT is there any binocular vision? why/why not?
UNLIKELY - due to manifest deviation so early on in child’s life unless very early surgery
what kind of responses will you find on BV tests in someone with infantile SOT?
suppression response
in nystagmus blockage SOT, when does amplitude increase>
aBduction
in nystagmus blockage SOT, what happens when you cover one eye or both eyes?
nothing - it stays the same
why does someone develop nystagmus blockage SOT?
trying to stop the nystagmus as amplitude descreases on aDduction
is nystagmus blockage congenital or acquired?
congential
is nystagmus blockage manifest or latent?
manifest
when does non-accommodative SOT occur?
between 6 months and 2 years
is amblyopia common in non-accommodative SOT?
yes
what happens when you use rx in non-accommodative SOT?
no change in size of the tropia - used to correct VA only
does the deviation chnage in size at Distance or Near in a non-accommodative SOT
approx the same at both dist and near
when does late onset SOT occur?
between 2-8+ years old
what happens in early stages of late onset SOT?
may have been intermittent originally
diplopia –> suppression
do you get NRC or ARC in late onset SOT?
NRC
do you have sensory and motor fusion in late onset SOT?
yes
what happens when you use rx in late onset SOT?
no effect
when do you refer with a late onset SOT?
any sign of neuroglial problems, papilloedema, motility problems, nystagmus
what is late onset SOT associated with ? (cause)
brain tumour
what is the aetiology of fully accommodative SOT?
uncorrected hyperopia
what is the approx amount of hyperopia in fully accommodative SOT?
+3.00 to +6.00
cover test results with a fully accommodative SOT?
without glasses = SOT (unilateral or alternating)
with glasses = SOP all distances with good recovery
binocular functions in fully accommodative SOT?
good with rx
onset of fully accommodative SOT?
2-5 years old
does fuly accommodative SOT get worse at any point?
parents may report SOT larger when tired or unwell
is amblyopia likely in fully accommodative SOT?
no unless anisometropia present too (unlikley)
which type of SOT is usualy hyperopic but can be emmotropic?
convergence excess SOT
what is the cause of convergence excess SOT?
high AC/A ratio
cover test results with convergence excess SOT?
Near with accomm target = SOT
Near with light = SOP
Distance = SOP
what is the approx AC/A ratio in convergence excess SOT?
greater than 5:1 , could be as high as 15:1 (usually 8:1)
is amblyopia likely in convergence excess SOT?
only if uncorrected anisometropia
cover test of near SOT
Near = SOT
Distance = SOP
what is the likely refractive error in Near SOT?
nil
what is the AC/A ratio in Near SOT?
normal
what is OM like in Near SOT?
normal
is amblyopia likely in Near SOT?
no
who are the most likely patients with a distance SOT?
elderly or highly myopic
cover test results of distance SOT?
Near = SOP
Distance = SOT
How does a distance SOT start?
intermittent at distance and becomes more constant with time
With high myopia, how does a distance SOT progress?
progressive - can become constant
can cause restricted abduction and elevation in extreme myopic cases
with a distance SOT, which palsy do you need to exclude?
6th nerve palsy
which SOT is the most rare?
cyclic SOT
what happens with cyclic SOT?
constant on “squinting day” with no demonstrable binocular function
what is the BSV like with a cyclic SOT on a “straight day”?
BSV with little or no SOP
what questions to include in your H+S
which eye?
direction of strab
how often (constant/intermittent)
how long has it been there? (likelihood amblyopia)
when do parents notice (during a particular activity)
is their vision good?
Premature?
birth weight?
birth trauma?
any ocular pathology or treatment ? (secondary/consecutive)
GH - good? meds? allergies?
FH - strab? amb? refractive error?
which 2 conditions are you more likely to have a manifest deviation?
Downs or cerebral palsy
when is amblyopia common with SOT?
constant SOT (except if alternating)
or consecutive
when is amblyopia uncommon with SOT?
intermittent SOT unless decompensated and untreated in childhood or anisometropia
how is vision with secondary SOT?
poor
why do a cover test to investigate SOT?
enables differentiation of different types of SOT
perform with and without rx
Near and distance
with a light and accommodative target at near if SOT
can look for DVD & MLN
why do OM with SOT?
may find SO underactions and IO overactions with a V pattern esp in constant SOT
why do NPC with SOT?
important indicator of control for near
how do you measure the angle of SOT with poor vision?
krimsky
how do you measure the angle of SOT (best method)?
PCT
how do you measure the angle of SOT with uncooperative child?
Prism reflection test
when should you use the hirschberg test?
babies
what is CBA?
controlled binocular acuity
who has CBA?
all px’s with intermittent SOT where cooperation allows
how do you perform CBA?
at near using budgie stick
at distance using logMAR
line before they break down
what is CBA in convergence excess SOT?
Near - SOT will occur as px accommodates to read further down the chart
what is CBA in Near SOT?
Near SOT all the time not affected by accommodation
what is CBA in fully accommodative SOT?
near with Rx - no SOT px remains SOP all the way down the chart, controlled when wearing glasses
what is the best method to measure AC/A angle in convergence excess SOT?
gradient method using -3.00 lenses in both eyes and px fixes on 6/6 letter
if px have ARC do you treat them? (constant SOT)
no
how do you carry out the post-operative diplopia test?
- prism placed before deviated eye
- base opposite deviation , then base in same direction
- prism increased until px notes diplopia
- fixation target = light
if double v quickly = bad candidate
if no double = good candidate
if a child is greater than 1 year, what % of cyclo do you use?
1%
if a child is 6-12 months WITH LIGHT IRIS, what % of cyclo do you use?
0.5%
if a child is 6-12 months WITH DARK IRIS, what % of cyclo do you use?
1%
if a child is 3-6 months, what % of cyclo do you use?
0.5%
how long do children need to wear glasses before accurate diagnosis?
1 month or longer
what are the aims of investigation?
- diagnose type of strab and angle size
2.does the px with constant SOT have the potential for BSV
3.can you restore BSV in all positions of gaze
4.record area of suppression (post-op dip test) and record density of suppression (amblyopia treatment)
which SOT has the best visual prognosis?
fully accommodative SOT
What is the likely clinical diagnosis?
Cover Test:
Near with Rx = slight RSOT
Distance with Rx = minimal RSOT
Near without Rx = moderate RSOT
Distance without Rx = small RSOT
constant with accommodative element
what is the likely clinical diagnosis?
Cover test:
Near with accom target = RSOT
Near with light = slight SOP good recovery
Distant = slight SOP good recovery
convergence excess SOT
what is the 1st stage of management?
IMPROVE VISION
if referring child to hospital, do you prescribe?
yes - will be seen at hospital later
what is the 2nd stage of management?
imporve alignment of visual axes
what does stage 2 management include?
restore BSV
enhance ARC
if no potential for BSV - CONSIDER RESTORATIVE SURGERY (cosmesis)
why do you not treat someone older than 5 for amblyopia?
could leave them with intractable diplopia - therefore use a sbisa bar before treating
how much more likely are people with manifest stab to have depression?
10X
why should you refer someone with a cosmetically large strab?
it affects their self-esteem, relationships, employment etc ..
WILL HAVE A CONSULTATION WITH DOC
what are some conservative treatments for strab?
- observe/monitor
- optical (prisms or manipulating rx)
- orthoptic excercises
what are some non conservative treatments for strab?
surgery or botox
why give a hyperopic glasses to treat?
relax accommodation and convergence
order FULL PLUS in all accommodative SOT
which prisms do you give in SOT and why?
base out
resolves diplopa
with late onset SOT what is important to measure before you do surgery?
binocular function with prisms
which orthoptic exercises do you use for SOT?
improve negative relative convergence (CATS)
when do you give orthoptic exercises?
intermittent SOT
other than stereograms, what other orthoptic exercis can you use?
lend prism bar - BASE IN exercise
what surgery needs to be done if the angle is larger at near?
medial rectus recessions
what surgery needs to be done if the angle is larger in distance?
both lateral rectus resections
what surgery needs to be doen if near angle = distance angle?
MR recession and LR resection in one eye
what type of botox is used for SOT management?
BTXA (botulinum toxin type A injection)
how does btxa work?
neuro-toxin which paralyses muscle into which it is injected, giving the antagonist the advantage
when is it useful to use BTXA?
consecutive SOT
residual SOT
secondary deviations
why is it useful to use BTXA in consecutive SOT?
already had surgery
why is it useful to use BTXA in residual SOT?
reducing deviation might allow px’s to regain control
why is it useful to use BTXA in secondary deviations?
when vision is poor in one eye
what is an advantage of BTXA?
temporary results
useful to confirm if post-op diplopia test suggests intractable diplopia possible outcome
used when px is unfit for anaesthesia
is consecutive SOT constant or intermittent?
can be either
why does consecutive SOT occur?
surgical overcorrection of XOT
when do you use an adjustable suture?
secondary SOT to fine tune the position of the eyes post-op in ADULTS
why are patients left slightly SOT after surgery or BTXA (secondary SOT)?
to guard against consecutive XOT
how do you manage a constant SOT with accommodative element?
FULLY correct hyperopia
treat amblyopia
refer for surgery/BTXA
why do you refer for surgery/BTXA in constant SOT with accommodative element?
- restore BSV if there is potential
- Cosmesis restore to improve appearance
(choice of surgery depends on near and distance measurement)
how do you manage infantile SOT?
cycloplegic refraction
amblyopia treatment
surgery
why do you refer for surgery in infantile SOT?
improve cosmesis
restore reduced form of BSV
when should you refer someone with infantile SOT?
before 2 years old
how do you manage constant SOT without accommodative element>
- prescribe Rx for vision
- treat amblyopia
- refer is symptomatic or worried out cosmesis
how do you manage nystagmus blockage SOT?
refer
how do you manage constant late onset SOT?
Refer HES for surgery or BTXA
what are the primary constant SOTs?
constant without accommodative element
constant with accommodative element
late onset
nsytagmus blockage
infantile SOT
how do you manage fully accommodative SOT?
prescribe full correction - full time glasses wear
PARENTS MAY COMMENT CONTROL INITIALLY WORSEN INITIALLY
recall with fully accommodative SOT
12 months
is amblyopia likely in fully accommodative SOT?
rare
what do you need to warn parents of with a fully accomm SOT
it will only get better with the glasses, otherwise they may think you made it worse
if a small hyperopic rx, how do you treat fully accomm SOT?
exercises: MISTY/CLEAR or LIFT UP AND REPLACE GLASSES
how does lift up and replace glasses work?
lift glasses up - child now accommodates to see clearly without glasses, this will also cause then to converge therefore cause an SOT & diplopia. Aske them to relax their accommodation and allow the image to become blurred and let them note that it is now single Then encourage them little bit by little bit to become clearer whilst maintaining a single image
in a fully accommodative SOT, when do you indicate surgery?
NEVER
who manages a fully accomm SOT?
optometrist
how do you manage convergence excess SOT?
- cyclo refraction
- fully correct if hyperopic
- under correct if myopic
- treat amblyopia (monitor carefully)
- achieve control of deviation to turn into fully accommodative SOT -BIFOCALS
why do you give bifocals to convergence excess SOT?
stop them from accommodating so much, then turns them into fully accom SOT
bifocals in convergence excess SOT?
minimum near add to eliminate sOT and have good BSV
amount of near add then reduced by +0.50 every 6 months
Aim to leave straight with single vision lens
who would you consider giving a bifocal to when treating convergence excess SOT?
- those unwilling for surgery
- distance SOP is small
- child old enough to use correctly
the maximum near add you can give to treat convergence excess?
+3.00
what is a contra indication for using bifocals for convergence excess?
large deviation and AC/A greater than 10:1
why could you give bifocals post-operatively?
still becoming SOT for near on accommodation
how do we manage near SOT?
refer for HES surgery
how do we manage distance SOT ?
prisms
refer for HES surgery
how do we manage cyclic SOT?
refer HES for surgery
convergence excess SOT will show..
esotropia on accommodation on near fixation
bifocals can be used to treat..
convergence excess SOT
adjustable sutures are particularly useful in which condition?
secondary SOT
