Non-Paralytic and Paralytic
Strabismus
Professor K N Jha, MS
Email: kirtinath.jha@gmail.com

Strabismus
A condition in which
visual axes of the two
eyes do not meet at the
point of object of
regard.

Types
• Concomitant ( Non-paralytic)
• Incomitant strabismus (Paralytic)

Concomitant strabismus
The misaligned eyes maintain their abnormal
relationship in all directions of the gaze.

Etiology
• Defective vision in one eye: high refractive
error, media opacities or ocular disease
• Disturbance in muscle equilibrium: defective
development /malinsertion on EOM/s
• Change balance in accommodation and
convergence e.g. a hypermetrope

Types of comitant strabismus
• Latent (Phoria) Manifest (Tropia)
• Convergent Divergent
• Intermittent Constant

Comitant strabismus
Symptoms
- Asthenopia
- Cosmetic disfigurement
- Subnormal vision
-Refractive error
-Amblyopia

Convergent strabismus
• More common in hypermetropes and commences in
childhood
• More common than divergent variety
• May commence in childhood following a febrile illness
• Diminishes with age
• May have a cyclovertical element
• May be associated with neurological disorders

Divergent strabismus
• More common in myopes
• Often commences at a later age , particularly
after loss of vision in one eye
• Tends to increase with age

Signs
• Deviation of the eye/s
• Refractive error
• Amblyopia
• Suppression
• Eccentric fixation

Investigation
• History
-complaint
-onset and duration
-Previous treatment
-treatment goals and expectation
• Diagnostic tests

Diagnostic tests
• Visual acuity and fixation pattern
• Cycloplegic refraction and funduscopy
• Head posture and exam of ocular motility
• Details of ocular deviation
• Test of binocular vision
• Forced duction test

Management
• Evaluation of the case
• Parental education
• Spectacle correction
• Amblyopia therapy
• Orthoptic training
• Surgical treatment-
Strabismus with binocular vision
-Without binocular vision

PARALYTIC SQUINT

Common cause of nerve palsies
• In children: Trauma, intrinsic tumors
• In young adults: Trauma , demyelinating
disease
• Older adult: Vascular lesion , tumors

Clinical features
Symptoms : Diplopia (binocular), vertigo
Signs:
• Strabismus
• Limitation of movement
• False orientation
• Compensatory head posture
• Changes in orbital tissues in long standing cases

• Primary deviation: deviation of the eye on the
affected side with normal eye fixing.
• Secondary deviation: Deviation of the normal
eye with affected eye fixing.

Compensatory head posture
• Face turn – Seen in cases of paralysis of
horizontally acting muscles
• Head tilt – Seen in cases of torsional deviations
• Chin elevation/depression – In vertical deviations

False projection
Demonstrated by closing patient’s normal eye
and telling him to point quickly at an object in
front of him

Investigation of a case of EOM
palsy
• Evaluation of squint
• Identification of involved EOM or nerve
• Finding out etiology by
- history
-ocular examination
-Neurological examination
-Special investigations e.g. USG,CT,MRI

Treatment
• Treat the underlying cause
• Palliative treatment: prisms /occluder on the
affected eye
• Permit time (At least 6 months) for
spontaneous recovery.
• Botulinum toxin injection overacting
antagonist of the paralyzed muscle

Features Paralytic Squint Non-paralytic squint
Deviation
Different in different directions
of gaze
Equal or constant in all
directions of gaze
Diplopia Present Absent
Ocular
movements
Restricted in the direction of
action of the paralyzed muscle
Full in all directions of gaze
Cover test
Secondary deviation > primary
deviation
Primary deviation =
secondary deviation
Compensatory
head posture
Present Absent
Onset Usually sudden Usually gradual
Neurological
findings
Common Uncommon
Vertigo & nausea Usually present Absent

Causes of uniocular diplopia
-Subluxation of lens
-Incipient cataract
-Multiple pupils
-Large iridodialysis
Causes of binocular diplopia
-Paralytic squints due to neurological causes
-Restrictive myopathies
-Myasthenia gravis
-Anisometropic glasses
-After squint correction if abnormal retinal
correspondence is present

Points to Remember
• Etiology of nerve palsies
• Differences between paralytic and non-
paralytic squint
• Differences between uniocular and binocular
diplopia
• Visual problems of squint