Orthoptics Flashcards
(22 cards)
What is binocular vision?
The brain’s ability to perceive an image with each eye as a single image
Involves:
Simultaneous perception
Fusion
Steropsis - depth perception
Wha is ‘strabismus’?
Manifest squint (tropia) - visible inwards, outward, upward or downward deviation of one eye
Latent squint (phoria) - the tendency of one eye to deviate under certain circumstances
Why do adults get diplopia with manifest squints
they are looking at two different things
What is amblyopia?
reduction of vision in one eye due to a lack of stimulation during the critical period of visual development
Causes of amblyopia?
Stimulus deprivation
Squint
Anisometropic - large difference in refractive errors of over 1 dioptre - eye with highest refractive error is affected
How can visual acuity be tested for in children?
Preferential looks Cardiff cards Kays pictures (picture form of Snellen chart) LogMAR (when child can read letters) Bailey lovie
How is Snellen’s vision recorded?
Fraction: numerator being distance away and denominator is the line of text read
How Is LogMAR vision recorded?
visual acuity is recorded as a decimal with 0 being normal and 1 being 6/60 so higher = worse vision
Negative number = better than normal
What is a concomitant squint?
squint that remains the same in all positions of gaze
What is inconstant squint?
Squint that changes in different positions of faze and is due to an extra ocular muscle imbalance
What actions does the superior rectus perform?
Elevation, intorsion ad adduction
What actions does the inferior rectus perform?
depression
extorsion
adduction
What actions does superior oblique perform?
Intorsion
depression
abduction
What actions does inferior oblique perform?
Extorsion
elevation
abduction
What actions do MR and LR perform?
MR - adduction
LR - abduction
How do nerve palsies arise?
trauma tumour vascular inflammatory infection
What are the causes of mobility defects in children?
Mechanical conditions - blow out fractures or thyroid eye disease
Myogenic conditions - tumour, inflammation, disease of EOM and myasthenia gravis
What do orthoptists do?
Diagnose, treat and manage disorders of vision, eye movements and binocular vision
Why would a child be referred to an orthoptist?
Presence of suspicion of a squint
Reduced visual acuity
Family history of squint/reduced VA in childhood
Why would an adult be referred to an orthoptist?
Presence of diplopia
Presence of squint - sudden onset or requiring cosmetic surgery
Asthenopic symptoms - eye strain
What is esotropia?
Deviation towards the nose
What is exotropia?
Deviation towards the temporal
