8.1.6 Manages children presenting with an anomaly of binocular vision.

Question 1

Fully accommodative SOT

Answer 1

 Primary intermittent SOT
 BSV & NRC present @ near when hypermetropia fully corrected
 Usually no amblyopia, unless strabismus present for a long time
 Full correction worn

Question 2

Partially accommodative SOT

Answer 2

 Constant SOT
 SOT decreased by at least 10^ with correction, but remains manifest
 Deviation tends to be greatest at near
 Amblyopia is common
 Full Rx worn – may require surgery for residual angle if >25^

Question 3

Heterophoria & problems at near

Answer 3

Near exophoria / convergence weakness
 XOP (10^ > @ N)
 May be an associated convergence insufficiency (NPC <10)
 Try to remove cause of decompensation i.e., working conditions
 Children – negative near add
 3 cat’s stereograms

Convergence insufficiency
 NPC <10
 Dot card / pen to nose

Accommodation insufficiency
 Correct hyperopia
 Jump accommodation useful

Meares Irlen/visual stress
 Headache, blur, excessive blinking, rubbing eyes, poor concentration, difficulty keeping place

Question 4

Amblyopia therapy

Answer 4

2. Refractive adaptation

 Full cycloplegic refractive correction worn – 18 weeks (PEDIG)
 2–3-month review after prescribing
 Expected VA improvement of 2-3 lines
 Allows for improvement of VA before starting occlusion/occlusion may be avoided in some cases

4. Occlusion of better eye
    May take form of adhesive plasters /patches worn on skin/frame
    Opaque CL
    Frosted glass
    Generally recommended 6 hours daily
    Higher-dose rate may be required in older patients/more dense amblyopia
5. Atropine penalisation
    Similar efficacy to 6-8 hours patching in patients with moderate amblyopia
    Not as useful in dense amblyopia
    Better eye is blurred by prevent accommodation
    1 drop 1% instilled on weekends

Question 5

Follow up

Answer 5

 Patient should be reviewed regularly, minimum every 3 months
 Age in years = review in weeks (4 years old = 4-week reviews)
 VA stable 2 consecutive visits = consider tapering off/stopping occlusion
 Amblyopia persist & px compliant = refraction & fundus check, increase occlusion to FT or change therapy
 Amblyopia persist & px non-complaint = instruction leaflet, reward scheme, video game therapy, change regime

Question 6

Esotropia:

Answer 6

• Intermittent:
  
  • Fully accommodative —> Hyperopic between +3D to +6D; Onset 1.5 - 2.5 years; Child has to overcome higher plus Rx hence converges more & if does it too much & too frequently then fusional reserves overcome & breaks down to esotropia.
    
    • Management is fully correct Rx & squint will go, treat any amblyopia if present, surgery is useless as when the px becomes straight without spex, then puts their plus spex on, it’s likely to induce an exotropia so not worth it
  • Convergence Excess —> Onset 2-5 years; High AC/A so loads of convergence for little accommodation, squint at near but straight at distance & goes with +3D Add normally.
    
    • Management requires bifocals so they use the extra plus for reading, this is useful when waiting for their surgery as bifocals suck for children!
  • Distance & Near Esotropia —> BSV should develop as binocular in at least one direction for each.
    
    • Correct Rx. Surgery only for cosmesis.
    • DD distance EsoT from 6th palsy (very important)
  • Cyclic Esotropia - BSV on straight days & constant esotropia with suppression on alternate days. Unlikely amblyopic as binocular for large parts of the day.
    
    • Correct Rx. Treat with surgery
  • Non specific
• Constant:
  
  • With Accommodative Element —> Onset 1.5-3 years; Esotropia increases at near & will still be there with Rx, just reduced, leading to suppression & amblyopia unless alternating.
    
    • Management is correct Rx, treat any amblyopia, surgery only if with spex on, the deviation is still cosmetically poor, surgery for deviation without spex won’t work as already explained above.
  • Without Accommodative Element is Infantile & Nystagmus Block Syndrome. Infantile - Large angle & will alternate with cross fixation so little amblyopia present as suppression alternates but poor prognosis for BSV even if early treatment. Abnormal OKN, IO overaction.
    
    • Correct Rx, amblyopia & use bot toxin as some paed doctors prefer not using general anaesthetic but sedating infant in a different way. They then look at surgery later on.
    • Nystagmus block - Large angle (BEs may appear convergent), miosed pupils, face turn toward fixing eye, nystagmus increasing on lateral gaze. Correct Rx & treat amblyopia but harder with nystagmus latent component, surgery very unpredictable!
  • Sensory —> Poor VA in one eye leads to esotropia; Onset 6 months to 7 years when accommodative convergence most active. Vision loss so severe that fusion mechanism affected.
    
    • Management is treat cause of poor VA, any amblyopia even if superimposed on cause of poor VA, correct Rx, surgery results unpredictable with poor VA
  • Consecutive —> Intentional part of surgery. If px has exotropia initially, overcorrected to small angle esotropia. Eyes generally diverge with time so deviation will straighten

Question 7

Exotropia:

Answer 7

• Early Onset —> constant XT, little experience of being binocular, early onset suppression, primary reason for amblyopia is the squint & not something in the fundus for example.
  
  • Low chance of BSV after surgery so cosmetic. Treat amblyopia if in plastic period
• Decompensated Phoria —> diplopia experienced. If alternating tropia, then implies BSV previously (remember that suppression alternates if tropia alternates so equal VA & BSV). If had from young age, most likely amblyopic! Fresnel prism needs to be used to correct diplopia. Surgery is also available. Refer to lecture -
• Distance & Near —> controlled at one distance so BSV can develop as intermittently controlled.
• Sensory —> eye drifts out as poor eye not being utilised very much! Surgery gives poor results/variable results. Try correcting amblyopia superimposed and treat cause of poor VA.
• Consecutive —> most likely a mistake by the surgeon. Requires more surgery to align eyes.

Question 8

Post Operative Diplopia Test:

Answer 8

• Surgery can move px outside their suppression scotoma causing diplopia awareness. Adults cannot reinitiate suppression! It may become intractable!
• This test simulates a range of potential surgical outcomes and seeing if px becomes aware of diplopia. Done using prisms by orthoptics. You now have a range of outcomes you can leave the px with.

Question 9

Botulinum Toxin:

Answer 9

• Botulinum toxin causes a temporary, partial or complete, paralysis (weakness) of the muscle into which it has been injected. To begin with, you may notice a temporary reversal of your squint, followed by gradual straightening of the eyes as the paralysis wears off.
• The treatment takes effect within 2 to 3 days and will be at its greatest 1 to 2 weeks afterwards. The effect lasts for 2 to 3 months and then gradually wears off.
• May experience temporary diplopia which would stop you from driving until corrected. This is the main side effect
• This injection is good if surgeon worried patient may experience diplopia post operatively or if unsure if they are aiming for a functional result. Injection done before surgery to see what will happen
  
  • They will leave px slightly esotropic so long as there is no post operative diplopia. Eyes naturally diverge with time so straightens.
    
    • Surgeon may do post op diplopia test, then injection, then surgery

Question 10

2 Main Mechanical Types: Brown’s & Duane’s

Answer 10

• Causes:
  
  • Duanes - Mechanical; fibrosis or inelasticity of LR &/or that the MR inserts abnormally. Neurogenic; abnormal innervation of LR due to embryonic developmental issue at 4-8 weeks
  • Brown’s - short or tight SO tendon sheath hence stiffer & less flexible. Acquired or congenital. Injury to trochlea, RA
• Motility:
  
  • In Duane’s - the eye affected will Widen its fissure on moving towards the area of limitation & will Narrow its fissue when moving the opposite way
• H&S
  
  • Ask same questions as in 8.1.4
• Cover Test:
  
  • Brown’s —> HypoT in up gaze but normally no movement or little in primary
  • Duane’s —> Normally EsoT in primary or next to nothing due to it being mechanical
• AHP:
  
  • Brown’s - Chin up, tilt to lower eye (eye with Brown’s)
  • Duane’s - Face turn
• Management for both:
  
  • Correct refractive error
  • Treat any amblyopia (unlikely)
  • Possible surgery (unlikely) as condition controlled in PP but considered if marked AHP or poor cosmesis

Question 11

Orbital Injuries

Answer 11

Blow out fracture - bony injury - most commonly to inferior or medial wall (thinnest). A break of one or more of the bones that surround the eye due to the force of the strike.

• Enophthalmos normally occurs - globe displaced backwards & down due to fracture in orbital floor
• Limitation of movement caused by entrapment of tissue - if medial wall fractured then medial rectus trapped for example making it difficult to move in the opposite direction
  
  • Retraction of the globe - if eyes move towards opposite side of site of entrapment
• IR wall fracture causes hypoT & no normal elevation
• Symptoms - diplopia (possibly easier to deal with if eyes are straight in p.p), pain on eye movement, blurred vision (ON damage, RD etc)
• Management - don’t always need surgery unless wanting to improve field of BSV if px has tropia or to get rid of fracture wall debris & put implant in place.
  
  • Diplopia should improve with time & prism can be used if needed

Question 12

3rd Nerve

Answer 12

• Can either be affecting superior or inferior division
  
  • Superior = SR + Levator
    
    • Affected eye become HYPOtropic & partial PTOSIS
    • AHP = Chin elevation
  • Inferior = IO, IR, MR, Sphincter pupillae & Ciliary muscle
    
    • Exotropic with little or no vertical deviation
    • AHP = Face turn to eye without the palsy, Tilt to lower eye if vertical deviation
• What does it look like?
  
  • Primary position - ExoT & HypoT, Ptosis
  • Abduction is AOK, Adduction is not
  • Limited elevation & depression
  • Pupil dilation (if pupillary involvement - this is really bad for the px!)
• Causes - M (microvascular) A (aneurysm) T (trauma) E (episodic)
• Management - Emergency referral for any acute diplopia/palsy within 24 hours; emergency ASAP if pupil involvment as could be aneurysm.
  
  • HES need to determine cause so CT/Blood tests/MRI ordered
  • Px made comfortable with prism (fresnel), occlusion, Botox
  • Palsy may take up to 12 months to recover so fresnel can be changed later on
  • Surgery if recovery inadequate or symptomatic/poor cosmesis

Question 13

4th Nerve

Answer 13

• SO affected
• What does it look like?
  
  • Primary position - HyperT, Head tilt & chin depression
  • Adduction causes IO overaction, Abduction AOK
  • Limited depression on adduction
• 3 Step Test
  1. Look at primary position: affected eye has HyperT
  2. WOOG - worse on opposite gaze. Deviation will increase
  3. BOOT - better on opposite tilt. Deviation will increase on same side tilt
• Management - same as 3rd nerve, ignoring pupil involvement

Question 14

6th Nerve

Answer 14

• Abducens nerve
• What does it look like?
  
  • Marked EsoT in the (distance?)
  • Adduction AOK, Abduction limited
• Management - same as 3rd nerve, ignoring pupil involvement. If associated papilloedema then emergency