Week 9 - Management of concomitant strabismus Flashcards
What factors need to be considered when assessing suitability for treatment?
• Age
• Age at onset
• Type of strabismus
• Angle of strabismus
• Depth of sensory adaptations
• Cooperation of patient and parent
Age:
• 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
Age at Onset
• 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)
Type of strabismus:
• some Pxs respond better to refractive/orthoptic treatment than others
• different methods of treatment are more appropriate for different types
Angle of Strabismus
• 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
Depth of Sensory Adaptations
• the deeper, the worse the prognosis
Cooperation of Patient and Parent
• must have high levels of interest and perseverance and reasonable intelligence
• parents must give time for supervision of exercises
Accommodative Esotropia types:
• Fully accommodative esotropia
• Esotropia with Accomodative Element
• Convergence excess - High AC/A ratio
Fully Accommodative Esotropia presentation
• 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
Fully accommodative esotropia: Management
• 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
Esotropia with Accommodative Element presentation
• 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)
Esotropia with Accommodative Element: Management
• 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^
Convergence excess presentation:
• 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).
Convergence excess: Management Depends on…
•Depends on the AC/A ratio
• Also if near deviation is >25 - 30^ refer for surgery
Convergence excess: Management
- 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
Convergence excess: CL Mangement?
• 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
Convergence excess: Management: Increase VA? Surgery?
• 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
Non-Accommodative Esotropia’s:
• Constant
• Intermittent
Non-Accommodative Esotropia’s: Constant
• Onset 1-2 years
• Strabismic amblyopia common
• Often have an associated vertical deviation
Non-Accommodative Esotropia’s: Intermittent (Near)
• 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
Non-Accommodative Esotropia’s: Intermittent (Distance)
• 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
Non-Accommodative Esotropia’s: Intermittent (Cyclic)
• 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
Consecutive Esotropia
• Spontaneous - following XOT (rare - occurs with DVD)
• Post-operative - following overcorrection of an XOT
Symptomatic (secondary) esotropia
• Following severe visual loss in childhood, due to muscle tonus
The management of non-accommodative SOT is almost always…
• 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
Infantile Esotropia:
. 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!!!
Nystagmus Blocking (or compensation) Syndrome
• 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.
Distance exotropia: description
• 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
Distance exotropia: Management
• 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
Near Exotropia (Convergence Insufficiency) presentation
• 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
Near Exotropia (Convergence Insufficiency): Management
• 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.
Constant Exotropia:
• 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
Constant Exotropia: Management
• 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
Consecutive Exotropia:
• 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
Consecutive Exotropia: Management
• partial correction of hyperopia + Base out prism
• vergence exercises sometimes helps
• remedial surgery
Symptomatic (Secondary) Exotropia
• Due to severe loss of vision in one eye in adult life
• Management = Cosmetic surgery
Onset of Exotropia before 1 year old
• usually symptomatic (or secondary) due to visual loss from birth
• rarely congenital exotropia, often with nystagmus and DVD
Management
• No optometric treatment - refer
