BVP - Strabismus Assessment I - Week 11 Flashcards
Define strabismus.
A misalignment of one visual axis from fixation in the presence of full opportunity to fuse
Define phoria.
Misalignment of one visual axid from fixation when the opportunity to fuse is removed, but accurate alignment when fusion is allowed
Define sensory fusion.
Ability of the eyes to contribute to the binocular percept
What is first degree fusion? Explain.
Simultaenous perception - being aware of an input into each eye that is different, such as Maddox rod and torch
What is second degree fusion? Explain.
Superimposition - being aware of an input into each eye that is similar and in the same position such as a phoria card
What is third degree fusion? Explain.
Stereopsis - being aware of depth due to stimulation of disparate receptions
Clinically, what is the common way to measure sensory fusion?
Stereopsis - third degree fusion
Define motor fusion. What is it measured with?
The ability to maintain motor alignment to achieve sensory fusion
Measured with prism in free space
Strabismus develops due to an imbalance between what two factors?
Factors which increase the demands on fusion (if this side is heavier, strabismus will develop)
Factors which improve the quality of fusion (if this sime is heavier, no strabismus)
List three factors which increase the demand on fusion.
High refractive error
Abnormal innervation
Eye muscle disturbance
What high refractive error will especially cause strabismus and what kind?
High hyperopia causing esotropia
List 4 factors which decrease the quality of fusion.
Congenital lack of fusion
Reduced acuity in one eye
Peripheral retinal disease
Nystagmus
List 3 things that can reduce acuity in one eye leading to strabismus.
Anisometropia
Amblyopia
Dracula dystrophy/disease
If there is esotropia in the immediate family, what is the chance of esotropia in a patient?
17%
What proportion of esotropia presentations are pseudostrabmisbus?
50%
