lecture 2 - strabismus, latent and manifest Flashcards
(39 cards)
heterotropia is… strabismus
manifest or squint
Heterophoria is …. strabismus
heterophoria
tropia
both fovea aren’t looking at the same object
can you always see a strabismus
no - need to do cover test
what causes psuedostrabismus
epicentral folds wide inter pupillary distance unilateral myopia or exophthalmos facial asymmetry large angle kappa
what is angle kappa (K)
the angle between the centre of pupil and corneal reflection
in normal people what is angle kappa (K)
3 - temporally to posterior pole
in central corneal reflexes what is angle kappa
0
if the fovea lies nasal to the posterior pole what is angle kappa
negative - as corneal reflection is temporal
how to detect pseudo strabismus
use corneal reflection and see if they are symmetrical
use cover test
what is cover test used for?
pseduostrabismus
latent (phobia)
manifest (tropia) deviation
what is cover/uncover test used for?
used as a test to detect manifest
what is alternating cover test for?
best test to detect Heterophoria as it fully dissociates
if you find esotropia at near …
also use a light
why do you always use corneal reflections initially?
easier to do with young children and adults with learning difficulties and can determine if someone has eccentric fixation
when you are not using your fovea for central fixation
eccentric fixation
what is the accommodative target for cover test
line above worst VA or toys for infants
cover test is only as good as…
patients fixation
what is the largest reason for misdiagnosis
poor fixation
how do you control a px’s fixation
ask them questions about it - eg, when looking at bird, ask what colour the beak is, how many legs is he standing on etc
when do you look at the eye on cover/uncover
as you are covering one eye you observe the movement of the other
COVER/UNCOVER:
if eye moves out
esotropia
COVER/UNCOVER:
if eye moves in
exotropia
COVER/UNCOVER:
if eye moves up
hypotropia
