1. Introduction to Orthoptics Flashcards
What is BSV?
It is the ability to use both eyes to contribute to a common single perception.
It allows 1 image to be seen even if you have 2 eyes.
Who can’t have BSV?
Uniocular patients- px’s with 1 eye
What is heterotropia (manifest squint)?
This is the misalignment of the visual axis. Where 1 eye is either deviated inwards, outwards, up or down. And the other eye is straight.
Heterotropia can alternate between 2 eyes. What does it imply when equal alternation vs alternative squint?
Alternative squint- heterotropia alternates between BEs- in eyes with almost equal VA. Unequal RX= one eye will alternate the strabismus.
Why is alternating squint a good sign in children?
It suggests that the child is using both visual pathways and they will not develop amblyopia/ lazy eye. Hence, child will not require occlusion therapy.
Microtropia meaning
Small angle heterotropia- 10 dioptres or less. here BSV is present even if patient has tropia.
Esotropia meaning?
What is seen with corneal reflex?
Deviation of one eye inwards when both eyes are open.
What is seen– reflection on the temporal side of the eye.
Exotropia meaning?
What is seen with the corneal reflex?
Deviation of 1 eye outwards.
Corneal reflex seen nasally.
Hypertropia meaning?
Deviation of one eye upwards when both eyes are open.
Why do vertical deviations occur?
Due to muscle or nerve problems. this is when something is physically stopping the eye from moving. DUE TO MOTILITY DEFECT.
Why are vertical deviations less common compared to horizontal deviations?
Vertical fusional range is smaller than horizontal fusional range.
Vertical Range: 18-20^ BO.
Horizontal Range: 35-40^ BO.
What is the meaning of hypotropia?
Deviation of one eye downwards when both eyes are open.
How to differentiate between hypotropia vs pseudo ptosis?
Difference seen during cover test.
If eye lid moves up during CT- the lid follows the eye suggest the patient has a hypotropia.
Eye lids do not change position with pseudo tropia on the other hand.
What nerve palsy causes droopy eyes and vertical deviation- inability to look upwards?
3rd nerve palsy
Cyclotropia- what does the patient complain of?
Image tilt with tortional deviation.
4th nerve palsy - what 2 complains?
Image tilt and deviation.
Can torsion be managed with prisms?
NO
if significant then surgery is required.
Describe heterophoria (latent squint)
both eyes are directed towards fixation, eyes are straight ahead normally. However, the eyes deviate upon dissociation- that disrupts fusion.
Heterophoria, deviation depends on?
Fusional reserves: If insufficient, causes a deviation
Define Esophoria
The tendency for the eyes to deviate inwards on dissociation.
Define exophoria
A tendency of the eyes to deviate outwards on dissociation.
Define hyper/ hypophoria
A tendency for the eyes to deviate up/down on dissociation.
Cover/ uncover vs alternating- which one is used to identify a tropia vs phoria?
Tropia used to identify with cover/ uncover– uncovered eye is observed.
Alternating CT- covered eye is observed- used to find phoria.
What does prism cover test measure?
How much the eye moves to take up central fixation.
An objective test
Involves alternating CT & Use of prism to neutralize movement
