Week 9 - Management of concomitant strabismus

Question 1

What factors need to be considered when assessing suitability for treatment?

Answer 1

• Age
• Age at onset
• Type of strabismus
• Angle of strabismus
• Depth of sensory adaptations
• Cooperation of patient and parent

Question 2

Age:

Answer 2

• under 4 years - no co-operation for exercises
Rx and occlusion possible only
• Over 8-9 years - not possible to restore BSV:
cosmetic treatment only
• Most adults have come to terms with the strabismus and require refraction only. Some may want cosmetic surgery

Question 3

Age at Onset

Answer 3

• Very important
• To establish if the onset was within the first year (Px is more likely to have eccentric fixation, DVD, latent nystagmus)
• Next establish if onset is within the first 3 years
- Younger the Px is at onset and the longer time to presentation, the worse the prognosis.
- May never have developed binocularly driven cells and therefore cannot expect to obtain BV
• If very recent onset the Px is more likely to have distressing symptoms and may require immediate referral (esp. if incomitant)

Question 4

Type of strabismus:

Answer 4

• some Pxs respond better to refractive/orthoptic treatment than others

• different methods of treatment are more appropriate for different types

Question 5

Angle of Strabismus

Answer 5

• the greater the angle the worse the prognosis
• Intermittent squints better prognosis
• >20^- surgery indicated
• 15-20^ - other factors must be favourable for orthoptics
• <15^ - good for orthopties
• <6^ - microtropia, no orthopties necessary

Question 6

Depth of Sensory Adaptations

Answer 6

• the deeper, the worse the prognosis

Question 7

Cooperation of Patient and Parent

Answer 7

• must have high levels of interest and perseverance and reasonable intelligence
• parents must give time for supervision of exercises

Question 8

Accommodative Esotropia types:

Answer 8

• Fully accommodative esotropia
• Esotropia with Accomodative Element
• Convergence excess - High AC/A ratio

Question 9

Fully Accommodative Esotropia presentation

Answer 9

• Deviation is secondary to the presence of hyperopia
• Excessive accommodation for distance and near stimulates excessive convergence sufficient to cause a strabismus
• Onset usually 2-5 years; coincident with the increased use of accommodative effort
• AC/A ratio is usually normal
•BSV present in nearly all cases; may have microtropia if anisohyperopic
• Usually no or only slight amblyopia, unless strabismus is present for a long time

Question 10

Fully accommodative esotropia: Management

Answer 10

• Correction of refractive error
• full cycloplegic Rx for constant wear
• Review 6-8 weeks later
• Check that no more latent hyperopia has become manifest and alter Rx if big difference
• Check state of BV and microtropia if anisometropia present

• If amblyopia worse than 0.3, may require period of direct part-time occlusion if under 7 years.
NB if microtropia present, VA will never be equal
NB Often a refractive error is all that is necessary

Question 11

Esotropia with Accommodative Element presentation

Answer 11

• Constant Esotropia but increases with accommodative effort i.e without glasses
•Associated with hyperopia but residual angle still present with when corrected
• Usually amblyopia
•Onset 1-3 years; insidious
• BS depends on the age of onset; usually not present, but may have ABSV if small angle
• Associated vertical deviation common (I0 overaction of one or both eyes)

Question 12

Esotropia with Accommodative Element: Management

Answer 12

• depends on the size of the residual angle.
• Referral is required in all cases
• full cycloplegic result given
• treat any amblyopia by occlusion
•May require surgery for residual angle with glasses if >25^

Question 13

Convergence excess presentation:

Answer 13

• High AC/A ratio (>6:1)
• Strabismus at near only OR angle much greater at near
•Strabismus may only be present when looking at fine detail
• Onset 2-5 years, occasionally earlier
• Most have NBSV, rarely a microtropia
• Amblyopia rare (except in anisometropia)
• Most hyperopic but some are emmetropic or even myopic.
• It is important to differentiate convergence excess from non-accommodative NEAR SOT (has normal AC/A ratio) and undercorrected hyperopia ( e.g. do cycloplegic).

Question 14

Convergence excess: Management Depends on…

Answer 14

•Depends on the AC/A ratio
• Also if near deviation is >25 - 30^ refer for surgery

Question 15

Convergence excess: Management

Answer 15

• correction of refractive error - full cycloplegic Rx, unless Px is myopic then give a slight undercorrection
• amblyopia treatment (if necessary) by PT occlusion
• Bifocal spectacles - find an add that eliminates near deviation (by CT)
  enabling PX to maintain comfortable BS with adequate binocular VA for all near activities
• Start with +1.00 Add and increase in 0.50 steps
• Try Fresnels on one month trial
• Give large flat top seg set high bisecting pupil
• Carefully fit and give full instructions
• Gradually reduce add in time and discard if possible
• Use a bar reader to establish BSV
• Problem: dependency on add by young adults, poor fitting and compliance by children and wear and tear

Question 16

Convergence excess: CL Mangement?

Answer 16

• Contact Lenses - Calcutt (1984) reported that CLs (sometimes with extra +1.00D) reduced the angle by up to 15^, often producing a latent deviation and useful BSV. Needs further trials

• Orthoptics for use without the Rx - minority of Pxs > 6 years; good cooperation and small deviations

Question 17

Convergence excess: Management: Increase VA? Surgery?

Answer 17

• Increase binocular VA - increase-ve fusional reserves (usually needs some optical correction to achieve)

• Of minimal value on its own but can be useful in conjunction with other treatment or surgery

• Surgery - Bimedial Recessions

Question 18

Non-Accommodative Esotropia’s:

Answer 18

• Constant
• Intermittent

Question 19

Non-Accommodative Esotropia’s: Constant

Answer 19

• Onset 1-2 years
• Strabismic amblyopia common
• Often have an associated vertical deviation

Question 20

Non-Accommodative Esotropia’s: Intermittent (Near)

Answer 20

• Thought to be due to high proximal convergence or high tonic convergence
• Ortho or small SOP on distance fixation, Moderate/large SOT for near

• No amblyopia
• Often no significant refractive error
• Normal or low AC/A ratio
• Normal near point of accommodation
• No reduction in angle with plus lenses
• Normal sensory and motor fusion

• SURGERY

Question 21

Non-Accommodative Esotropia’s: Intermittent (Distance)

Answer 21

• Rare
• SOT for distance, SOP for near
• No significant refractive error
• VA normal and equal
• Full ocular movements (differentiates 6th nerve palsy or dysthyroid eye disease)
• SURGERY /BOTOX

Question 22

Non-Accommodative Esotropia’s: Intermittent (Cyclic)

Answer 22

• Esotropia occurring at regular intervals of time, BSV at others
• Usual pattern = 24 hrs SOT/ 24 hrs BSV = “alternate day strabismus”
• Onset 4-5 years or older
• Most emmetropic with equal VAs
• Diplopia rare
• Gradually becomes constant - then surgery can be considered
• Often associated with a psychogenic disturbance

Question 23

Consecutive Esotropia

Answer 23

• Spontaneous - following XOT (rare - occurs with DVD)
• Post-operative - following overcorrection of an XOT

Question 24

Symptomatic (secondary) esotropia

Answer 24

• Following severe visual loss in childhood, due to muscle tonus

Question 25

The management of non-accommodative SOT is almost always…

Answer 25

• Almost always surgical/BOTOX but **can try** • Can try prism for distance SOT where angle <10 A (Use Fresnel lens initially - adaptation) • Correct the refractive error to remove any asthenopia (independent of the deviation) • Any amblyopia must be treated

Question 26

Infantile Esotropia:

Answer 26

. Occurs before 6 months (usually 3-6 months) • Usually large angle (>40 A) • Same angle distance and near • Crossed alternating fixation • Less than half have ambyopia with eccentric fixation • Latent nystagmus develops later • DVD - develops later around 18 months Looks like a bilateral L palsy (distinguish by "dolls head" movement) Cross Fixation • **ALWAYS REQUIRE SURGERY!!!**

Question 27

Nystagmus Blocking (or compensation) Syndrome

Answer 27

• Convergent strabismus is adopted to lessen the nystagmoid movements which are reduced on convergence of the eyes • Pxs head usually turned away from side of fixing eye - produces greater convergence of this eye.

Question 28

Distance exotropia: description

Answer 28

• Manifest for distance fixation only, usually intermittently but may be constant • Most apparent during inattention, ill health and fatigue, and in bright light • Mostly females • Little refractive error • VA usually good and equal • Usually no symptoms as the sensory adaptations are good • Px may not have known about strabismus until told by others • **AC/A may be high in simulated** type or they have increased fusional control • **True type is unaffected by AC/A or fusion**

Question 29

Distance exotropia: Management

Answer 29

• Diagnosis of **True or Simulated 1st** • Correction of myopia or anisometropia • Low degrees of hyperopia best left uncorrected- unless surgery is going to be planned or amblyopia potential • Where angle is <15^ and BSV maintained most of the time, optical &/or orthoptic treatment may be of benefit - but usually only in the short term to delay surgery • Optical:negative lenses can be successful in the short term, where accommodation is good • Prisms (full base in - then gradually reduce) - short term • Tinted spectacles - useful in countries with high light intensity - again only short-term- high illumination has a dissociation effect • Most require referral for surgery • Orthoptist will use Newcastle Control Score to decide when Sx is required • **True - Bilat Lateral Rectus Recession** • **Simulated MR Resection with LR Recession in one eye**

Question 30

Near Exotropia (Convergence Insufficiency) presentation

Answer 30

• Most commonly occurs in the mid-teens when reduced convergence &/or increased myopia break down the BV, can be in adults - Presbyopia with > near add • Typically XOP at distance XOT at near • Pxs present with symptoms (diplopia, asthenopia) • Usually equal VAs, poor or no convergence, NRC and normal sensory fusion with poor positive fusional amplitude • Often myopic

Question 31

Near Exotropia (Convergence Insufficiency): Management

Answer 31

• If strabismus is constantly manifest for near and angle >25^ - refer • For smaller angles and only occasionally manifest: - Correct any myopia (this may be enough to make deviation latent) - Orthoptics - exercise base out prism vergences and Improve Conv Near Point if reduced - Prisms - base In just sufficient to enable BSV for near (Usually tolerated for distance) - gradually reduce the strength of the prism and combine with orthoptics - Most importantly improve convergence near point - If no improvement - refer for surgery.

Question 32

Constant Exotropia:

Answer 32

• Constant divergent strabismus, equal angles distance and near • Onset in early childhood: no symptoms, no sensory fusion • Closure of one eye in bright light • Often alternating, with equal VAs; homonymous fixation

Question 33

Constant Exotropia: Management

Answer 33

• Surgical correction for cosmetic (or occasionally functional) • Occasionally in children <7 years old - try-ve additions to eliminate strabismus on the CT in conjunction with exercises to establish BSV • Gradually try to phase out the -ve add over several years • If a divergent strabismus has a vertical component - orthoptics not successful

Question 34

Consecutive Exotropia:

Answer 34

• Spontaneous - usually occurs following early onset partially accommodative esotropia with a high degree of hyperopia. • Develops as the amplitude of accommodation decreases, or precipitated by the late correction of hyperopia •Post-operatively - usually several years after surgical correction of accommodative SOT - especially if hyperopic correction is now prescribed

Question 35

Consecutive Exotropia: Management

Answer 35

• partial correction of hyperopia + Base out prism • vergence exercises sometimes helps • remedial surgery

Question 36

Symptomatic (Secondary) Exotropia

Answer 36

• Due to severe loss of vision in one eye in adult life • Management = Cosmetic surgery

Question 37

Onset of Exotropia before 1 year old

Answer 37

• usually symptomatic (or secondary) due to visual loss from birth • rarely congenital exotropia, often with nystagmus and DVD Management • No optometric treatment - refer