Approach to a patient with diplopia

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Approach to a patient with diplopia

• Dr. R.R.Battu
• Narayana Nethralaya

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What does the faculty of BSV require?

• Perfect ( or near perfect ) alignment of the
  visual axes simultaneously on the object of
  regard
• Perfect ( or near perfect ) retinal
  correspondence
• Perfect central ( or paracentral ) fusional
  capability.
• Perfect ( or near perfect ) alignment of the
  retinal receptors
• Perfect ( or near perfect ) optics to allow only
  one image to be formed on the retina and the same
  single image to be formed on the other

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What is Diplopia ?

• It is when more than one image ( two ) of the
  object of regard are seen simultaneously
• This occurs when.(Mechanisms)
• More than one image of the object of regard is
  formed in the retinae of one or both eyes (
  monocular diplopia)
• The eyes lose their simultaneous alignment with
  the object of regard in one or more directions (
  or distances ) of gaze (incomitance of ocular
  alignment binocular diplopia)
• The eyes although aligned, send images to the
  brain which disallow fusion ( aniseikonia )
• Local retinocerebral adaptations to misalignments
  in early life go askew (paradoxical diplopia,
  loss of suppression)
• Rarely, purely cerebral mechanisms

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Monocular vs Binocular Diplopia

• Key question
• Is the double vision present even on monocular
  eye closure?

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Monocular diplopia

• More than one image of the object of regard is
  formed in the retinae of one or both eyes..
• Irregular astigmatism ( nebular scars, haze,
  corneal distortion)
• Subluxated clear lenses
• Poorly fitting contact lenses
• Early cataract
• Iridodialysis, polycoria, large iridotomies
• Macular disorders edema, CNVM etc

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Binocular Diplopia

• The eyes lose their simultaneous alignment with
  the object of regard in one or more directions (
  or distances ) of gaze (incomitance of ocular
  alignment binocular diplopia)
• Key clues
• Anomalous Head Position
• Vision Blurry in one gaze position, better in
  another
• Vestibular signs
• Long tract signs
• Obviously misaligned eyes, proptosis
• Presence of partial ptosis
• Nystagmus

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Questions to be asked

• Is there a mis alignment?
• If so, in which directions ( or distances ) of
  gaze?
• Which are the hypofunctioning ( and
  hyperfunctioning ) muscles?
• Do they have a neurogenic pattern, or a
  restrictive pattern or a neuromuscular pattern
  or a myogenic pattern?

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Identifying muscle/s involved

• AHP
• Predominant face turn horizontal recti
• Predominant chin elev/dep vertical recti,
  pattern strabismus
• Predominant tilt Obliques

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Diplopia -

• Key questions
• Is the diplopia more for distance or near?
• Is the diplopia predominantly horizontal or
  vertical?
• In which direction of gaze are the images
  maximally separated?
• To which eye does the outer image belong?
• Is there a predominant tilt?
• In which position of gaze does the tilt increase
  maximally?

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Diplopia charting

• Diplopia is maximum ( separation of images) in
  the field of action of the paralysed muscle.
• The false image ( the image belonging to the eye
  with the hypofunctioning muscle ) is always
  peripherally situated
• Higher in upgaze, lower in downgaze, on the right
  in right gaze and on the left in left gaze

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Hess Charting

• Based on the principle of confusion
• Allows for identifying the position of one eye,
  while the other eye fixes in different positions
  of gaze.
• Effectively demonstrates Sherringtons and
  Herings laws
• Allows for more objective follow up also.

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The cover-uncover and alternate cover tests

• Probably the most important objective tests to
  evaluate muscle palsies
• Measurements with a prism bar allow for
  measurement
• Measure in the 9 cardinal gaze positions
• Distance and near

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Versions Ductions

• Allow to assess actual rotation limits
• Allow assessment of underactions and overactions
  of synergists

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Saccadic Velocity

• Floating saccades are suggestive of a nerve
  palsy or paresis
• Indirectly oblique saccade testing can be done.
  
• Normal saccadic velocity with limitation
  indicates a restricted muscle

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Forced Duction Testing

• Allows to assess forced movement in direction of
  restriction
• Important in Blow out fractures, TED, long
  standing strabismus with contractures
• Important to lift the globe and rotate

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Force Generation Testing

• Allows to identify residual power in a suspected
  paretic muscle. Usually done to direct management
• 6th N palsy
• Recess resect or muscle transposition

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Pointers to primary orbital disease

• Restrictive muscle hypofunction
• Proptosis
• Signs of orbital inflammation
• Signs of anterior segment, lid and adnexal
  hyperemia or inflammation

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Neurological disease

• Look for supranuclear, nuclear and infranuclear
  patterns
• Look for sensory ( visual ) abnormalities
• Look for nystagmus
• Look for vestibular auditory symptoms
• Look for other cranial nerve involvement
• Look for long tract signs

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CNS and orbital imaging

• Done for obvious neurological patterns
• Orbital inflammatory disease, proptosis
• Occasionally may avoid or delay
• Pupil sparing 3rd in a diabetic
• 6th Nerve in a hypertensive, image if no
  spontaneous recovery in a few weeks

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Imaging

• CT
• MRI
• Fat suppression
• Stir sequences
• MRA vs CT angio

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Ancillary tests

• Tests for myasthenia
• Tests of thyroid function
• X- ray chest
• Bloods

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Aniseikonia

• Occurs when image size disparity exceeds 5
• Previously seen in monocular aphakia
• May occur following keratorefractive surgery

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Convergence insufficiency

• Classically for near
• Could be primary or secondary

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Others

• Suppression scotomas
• Decompensated squints with Anomalous Retinal
  Correspondence
• Paradoxical diplopia