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STRABISMUS (SQUINT). Amaka Azie GPST2. It is a condition in which the eyes are misaligned Can lead to amblyopia in childhood or diplopia in adult hood Amblyopia (lazy eye),happens when because of lack of use of the eye in childhood, vision becomes poor
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STRABISMUS (SQUINT) AmakaAzie GPST2
It is a condition in which the eyes are misaligned • Can lead to amblyopia in childhood or diplopia in adult hood • Amblyopia (lazy eye),happens when because of lack of use of the eye in childhood, vision becomes poor • Latent squint– Also known as heteroPHORIA is a very slight squint not present all the time and can be seen in only certain circumstances • Manifest squint- HeteroTROPIA is present all the time
ANATOMY: MUSCLES OF EYE MOVEMENT • All movement of the eyes are enabled by the third nerve • Except superior oblique=> fourth nerve and lateral rectus =>sixth nerve • The third, fourth and sixth nuclei and the higher brain centres are involved • When the eyes are looking straight ahead =primary position
TYPES OF SQUINT Non-paralytic squint (concomitant squint): • Normal eye movements but only one eye is directed to the target. • Unrelated to the direction of gaze • More common in children Paralytic squint (Incomitant squint): • Weakness or paralysis of one or more muscles of eye movement • Dependent on direction of gaze and usually worse where eye is moved towards the field of action of affected muscle or nerve
IMORTANT TERMS • ESOtropia=> Inwards • EXOtropia=>Outwards • Hypotropia=>Downwards • Hypertropia=>Upwards
IMORTANT POINTS TO NOTE • Squint could be classified as congenital (Onset before 6 months) or acquired • Squint or some form of ocular misalignment are common in newborns. • Should be intermittent, reducing by 2 months of age and disappear by 4 months of age • Esotropias are more common than exotropias. Hypo and hypertropias are not common
Non-Paralytic squint SUSPECT IF: • May be noticed by parents • May be detected in pre-school screening • Children may tilt their head or chin to compensate for amblyopia SCREENING : Hirschberg’s test: Pen torch some distance in front of eyes. Reflection should lie centrally bilaterally on the cornea normally. It can also be used to estimate degree of deviation
CAUSES: • Family history • Neonatal jaundice • Prematurity • Fetal alcohol syndrome • Encephalitis, mengitis • Down syndrome/Turners syndrome • Refractive error • Cataracts • Retinoblastoma
Diagnosis=Cover/uncover testAlternate cover test=> Latent squint Cover /uncover test COVER TEST vs ALTERNATE COVER TEST Cover one eye for a few second while uncovered eye focuses on object. Remove and place on other eye. If initially covered eye moves outwards=> Esophoria. Alternate cover test detects latent squint by breaking bifoveal stimulation. Done by switiching occlude rapidly between both eyes
MANAGEMENT Referral to eye clinic • Neonate with constant squint, worsening squint from 2 months or squint still present after 4 months • Any older child with a suspected squint • Management include spectacles, patches, cycloplegic drops and surgery • Prognosis is good if detected early