Squint

Professor of Ophthalmology Dr. Amani Badawi

Table of Contents

1. Binocular Vision

   • Why Two Eyes?
   • Binocular Single Vision
   • Stereopsis
   • Importance of Stereopsis and Binocular Single Vision

2. Anatomy of Extraocular Muscles (EOMs)

   • Actions of EOMs
   • Origin and Blood Supply
   • Nerve Supply
   • Ocular Motility
   • Eye Movement Directions
   • Positions of Gaze

3. Classification of Strabismus

   • Apparent Squint (Pseudostrabismus)
   • Latent Squint (Heterophoria)
   • Manifest Squint (Heterotropia)
     • Concomitant Squint
     • Incomitant Squint

4. Types of Strabismus

   • Esotropia

     • Definition and Epidemiology
     • Types: Infantile and Accommodative Esotropia

   • Exotropia

     • Definition and Epidemiology
     • Types: Congenital, Intermittent, Sensory, Consecutive Exotropia

5. Examination & Management of Strabismus

   • History and Examination
   • Role of General Practitioners
   • Treatment Options
     • Eye Patch
     • Vision Therapy
     • Optical (Eyeglasses or Contacts)
     • Prisms
     • Eye Surgery
     • Botox Therapy

Squint

Squint

New words to Encounter

• Strabismus = heterotropias
• Esotropia = turn inward
• Exotropia= turn outward
• Hypertropia= turn upward
• Hypotropia = turn downward
• Amblyopia = Lazy eye (vision deficiency in an eye when the brain turns off the visual processing of one eye.
• Anisometropia= unequal refractive errors between the 2 eyes
• Diplopia = Double vision
• Monocular diplopia = diplopia persists when one eye is closed.
• Binocular diplopia= diplopia seen only when both eyes are open

Definition

Misalignment of one or both eyes so as the eye (eyes) is not looking straight at the object of regard.

It is an imbalance in the normal tone or coordination of one or more extra ocular muscle which results in a manifest deviation of the affected eye eye(s) may turn in, out, up, or down often referred to as: cross-eyed, crossed eyes,

CAUSES OF STRABISMUS

• result of the lack of coordination between the muscles of the eye responsible for eye movement
• • problems with the nerves* that transmit information to the eye muscles
• problems with the control center in the brain that directs eye movement
• the* lack of coordination prevents proper binocular vision* and keeps both eyes from gazing at the same point
• in adults, can be caused by stroke, thyroid problems, brain injury, or other trauma which disrupts the ability of the eye muscles to work properly

RISK FACTORS

• family history—if relatives have strabismus, a person is more likely to develop it

• refractive errors—extreme farsightedness (hyperopia) can develop strabismus due to the amount of eye focusing necessary to keep vision clear

• medical conditions—people with Down syndrome or cerebral palsy and people who have suffered a stroke or head injury are at higher risk for developing strabismus

Significance In Children

• Children need normally aligned eyes to develop vision.
• Strabismus in childhood is the second most common presentation of retinoblastoma.
• Strabismus is a common presentation for refractive errors.

Significance in Adults

• Frequent sign of neurological disease
• Frequent presentation of systemic disease ( Thyroid disease & Myasthenia)
• Cosmetology

Classification of strabismus

Broadly, strabismus can be classified as below: I. Apparent squint or pseudostrabismus. II. Latent squint (Heterophoria) III. Manifest squint (Heterotropia):

1. Concomitant squint
2. Incomitant squint.

Classification

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