Basics & Classification
Mahbuba Khondaker
PGDO Intern, School of Optometry
Aravind Eye Hospital
Introduction
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Misalignment of eye visual axis

Its may congenital or acquired
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It may also related with any other syndrome
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In some cases it is hereditary

Is a condition which can be unilateral or bi lateral.
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It is a common condition among children.
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It may also occur in adults.
Squint: Definition
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Squint is a misalignment of the two eyes so that both the eyes are
not looking in the same direction in same object.
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The misalignment can be-
•
•
Constant
Intermittent
Causes for squint:
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Birth injuries.
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Hereditary.
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Loss of coordination between the muscles of the two eyes
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Need for glasses
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Certain eye diseases interfering vision of one eye (e.g:
unilateral cataract

Illness - can make it obvious

Fatigue, stress or extended work load
Extra Ocular Muscles of Eye
Total 6 (4-rectus , 2- Oblique )
Muscles functions in particular gazes are-
•
•
•
Medial rectus (MR):
moves the eye toward the nose (Adduction)
Lateral rectus (LR):
moves the eye away from the nose (Abduction)
Superior rectus (SR):
primarily moves the eye upward and secondarily rotates the
top of the eye toward the nose (Elevation, Abduction, Intortion)
•
Inferior rectus (IR):
moves the eye downward & secondarily rotates the top of the
eye away from the nose (Depression, abduction, Extortion)
•
Superior oblique (SO):
primarily rotates the top of the eye toward the nose & secondarily
moves the eye downward (Adduction and depression)
•
Inferior oblique (IO):
primarily rotates the top of the eye away from the nose
secondarily moves the eye upward (Abduction and elevation)
Extra Ocular Muscles of Eye
Squint Classification


According to direction of deviation
According to amount of deviation in
different gazes
Squint Classification
Types of Squint and Definiton



A pseudosquint mimics a squint. It is caused
by prominent epicanthic folds causing one eye
to appear to be looking in.
Esotropia (not to be confused with entropion) is
a convergent squint, in which one eye is turned
inward.
Exotropia (not to be confused with ectropion) is
a divergent squint, in which one eye is turned
outward.
Treatment
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Goals of treatment:
Development of normal vision in both eyes.
• Straighten the eyes.
• To make both eyes work together

Treatment :
• Glasses/ Spectacles:
• Some type of squint are corrected by
glass (e.g accommodative esotropia)
• Patching of the lazy eye: Stimulate bad eye to see more
and improve vision.
• Surgery : Squint correction
Types: Squint Correction
Surgery


Resection
Recession