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