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