Squints Flashcards
Monocular terminology
Abduction Adduction Elevation Depression Intorsion (incycloduction) Extorsion (excycloduction)
Binocular terminology
Supraversion Infraversion Dextraversion Levoversion Convergence Divergence
Phoria vs Tropia
Phoria = intermittent
Tropia = always present
eg heterophoria heterotropia esotropia esophoria exotropia hypotropia hypertropia
Squint definition
Misalignment of the visual axis (visual axis of the two eyes do not meet at point of fixation)
Amblyopia definition
Subnormal vision due to abnormal visual experience
Sensory adaptation to diplopia
Around 50% of squints and must be treated before 10yo
Suppression definition
Inhibition of non-fixing eye to prevent diplopia
Diplopia vs amblyopia
Diplopia in adults (binocularity already established)
Amblyopia in children
Concomitant squint
Non-paralytic
Angle of deviation constant
No binocular vision therefore diplopia is absent
Some alternate when fixing
Usually children and congenital
Causes include refractive error, opacities in eye media or abnormalities of the retina
Incomitant squint
Paralytic
Angle of deviation differs in different directions of gaze
Causes include n palsy, mm weakness, muscle restriction (orbital mass or blowout fracture)
Diplopia is present and maximal
May develop TORTICOLLIS
Screening for squint
Use opthalmoscope to see where light reflex falls
Test VA (<3yo vs >3yo)
Assess for cataract, glaucoma, retinoblastoma, other
Examination for squint
External (large epicanthic fold) VA Red reflex, fundus, pupil reflex Cover test and alternate cover test Retinoscopy Extraocular motility (consider <3months) Corneal test for near and far Test each eye seperately
Treatment
Treat refractive error with spectacles - don't do surgery first as will return Amblyopia: patch good eye until visual system matures (<10yo) Find cause of incomitant squint and tx Surgical tx include rectus mm alteration
Adults vs children squint tendency
Adults exotropia
Children esotropia
