paediatric strabismus

Question 1

what is strabismus?

Answer 1

Strabismus is a misalignment of the eyes, which can be: horizontal, vertical, torsional, combine

Question 2

what are the clinical manifestations of pediatric strabismus

Answer 2

Strabismic amblyopia

• Develops if the strabismus is constant and unilateral
• Cortical suppression of image from strabismic eye
• Child does not use strabismic eye to see

Loss of binocular function and stereopsis: Eyes must be aligned for normal binocular vision, fusion, and depth perception (stereopsis)

Abnormal head posture: Child may adopt a compensatory head posture, e.g. head tilt, head turn, to keep both eyes aligned

Question 3

what is pseudo esotropia caused by?

Answer 3

Epicanthic fold (wide fold of skin covering inner part (medial conjunctiva)
Broad and flat nasal bridge

Question 4

what is commitant strabismus caused by?

Answer 4

• Angle of strabismus is same in all positions of gaze

- E.g. congenital esotropia, accommodative esotropia, intermittent exotropia

Question 5

what is incommitant strabismus caused by?

Answer 5

• Angle of strabismus varies in different positions of gaze
• Usually a/w limitation of eye movement, due to muscle restriction or paresis (weakness)
• Neurogenic causes (paralytic) e.g. CN3 palsy, CN4 palsy, CN6 palsy
• Myogenic causes (NMJ) e .g. myasthenia gravis (MG) (seemingly random ophthalmoplegia w/o obvious pattern)
• Mechanical causes (restrictive) e.g. orbital blowout fractures (with entrapment of extraocular muscles), thyroid eye disease (muscle fibrosis)

Question 6

what is the danger signs of strabismus?

Answer 6

Acquired strabismus
Diplopia
Limited eye movements, incomitant strabismus
Ptosis or other neurological signs
Poor vision
Abnormal red reflex

Question 7

what is the treatment for comitant strabismus?

Answer 7

• Correction of associated refractive error (if present)
• Correction of associated amblyopia (if present)
• Early strabismus surgery, to restore ocular alignment and binocular vision

Question 8

what is accomodative strabismus caused by?

Answer 8

Occurs due to (moderate) hyperopia of 4 dioptres (4D) on average 🡪 child accommodates to overcome uncorrected hyperopia 🡪 triggers near reflex triad (accommodation, miosis, convergence) 🡪 esotropia

Question 9

what is the treatment of acommodative esotropia?

Answer 9

Correcting hyperopia with full-time spectacle wear, which should correct the full amount of hyperopia

Fully accommodative esotropia: Eyes are aligned upon full correction of hyperopia with spectacles

Partially accommodative esotropia

• Residual esotropia present despite full correction of hyperopia with spectacles
• Requires strabismus surgery to correct the residual esotropi

Question 10

what is the treatment of intermittent exotropia?

Answer 10

Correction of associated refractive error (if present)

Correction of associated amblyopia (if present)

Eye muscle and convergence exercises

Strabismus surgery is indicated generally only when deterioration

• Worsening control, increasing frequency of tropic phase (> 50% of awake time in tropic phase)
• Increasing angle of deviation
• Stereopsis affected

Question 11

what is intermittent exotropia?

Answer 11

• Intermittent: eyes are sometimes aligned (phoric phase), sometimes misaligned (tropic phase)
• Eye deviates outwards (exotropia) when child is tired, sick, or at times of inattention; elicited on alternate cover test