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Approach to a patient with diplopia
Dr. R.R.Battu
Narayana Nethralaya
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
What is Diplopia ? It is when more than one image ( two ) of the
object of regard are seen simultaneouslyThis 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
Monocular vs Binocular Diplopia
Key question
Is the double vision present even on monocular eye closure?
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
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
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?
Identifying muscle/s involved
AHP– Predominant face turn – horizontal
recti– Predominant chin elev/dep – vertical
recti, pattern strabismus– Predominant tilt – Obliques
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?
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
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 Sherrington’s and Hering’s laws
Allows for more objective follow up also.
The cover-uncover and alternate cover testsProbably 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
Versions & Ductions
Allow to assess actual rotation limits
Allow assessment of underactions and overactions of synergists
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
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
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
Pointers to primary orbital disease
Restrictive muscle hypofunctionProptosisSigns of orbital inflammation Signs of anterior segment, lid and
adnexal hyperemia or inflammation
Look for supranuclear, nuclear and infranuclear patterns
Look for sensory ( visual ) abnormalitiesLook for nystagmusLook for vestibular – auditory symptomsLook for other cranial nerve involvementLook for long tract signs
Neurological disease
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
Imaging
CTMRI– Fat suppression – Stir sequences
MRA vs CT angio
Ancillary tests
Tests for myastheniaTests of thyroid functionX- ray chestBloods
Aniseikonia
Occurs when image size disparity exceeds 5%
Previously seen in monocular aphakia
May occur following keratorefractive surgery
Classically for nearCould be primary or secondary
Convergence insufficiency
Others
Suppression scotomasDecompensated squints with
Anomalous Retinal Correspondence
Paradoxical diplopia