Diplopia

approach to diplopia

The first point to clarify -
does the diplopia persist when one eye is covered?
If the diplopia persist, the Diagnosis is Monocular Diplopia, and the cause is usually intrinsic to the eye and therefore has no dire implications for the patient.

causes of monocular diplopia

• corneal aberrations - astigmatism
• uncorrected refractive error
• malingering
• psychiatric disesase
• catarect
• abnormal iris
• abnormal cornea - scarring, oedema, deposition.

diplopia alleviated by covering one eye - binocular diplopia, and it is caused by disruption of ocular alignment.

inquiry into binocular diplopia

• nature of double-vision (side to side vs partial vertical displacement)
• mode of onset
• duration
• intermittency
• diurnal variation
• associated neurologic / systemic symptoms

the causes of binocular diplopia is varied; infectious, neoplastic, metabolic, degenerative, inflammatory and vascular, however one must decide whether the diplopia is caused by a neurogenic cause, or a local disease causing globe restriction.

causes of restrictive diplopia includes...

• orbital pseudotumour
• myositis
• infection
• tumour
• thyroid disease
• muscle entrapment

these restrictive causes are diagnosed in concomittace with other associated S/S of local orbit diesease. - imaging may be required.

major causes of Binocular nonrestrictive Diplopia

• Intermittant / variable
• Myasthenia Gravis
• Internuculear Ophtalmoplagia
• Persistant
• Oculomotor nerve lesions
• Trochlear nerve lesions
• Abducens nerve lesions
• multiple ocular nerve palsies

others

• orbital myositis
• inflammation of orbits - may be inflammation due to infection, or autoimmunie
• painful
• acute onset
• Dx with fat-suppressed MRI
• orbital cellulitis
• infection involving the contents of the orbit
• pain with eye movement, eye swelling and redness
• more common  in children
• may be caused by
• acute sinusitis
• ophtalmic surgery
• orbital trauma
• contrast-enhanced CT scan of orbits and sinuses.
• orbital apex syndrome
• aka jacob's syndrome
• collection of cranial nerve deficits
• distinguishable from Rochon-Duvigneaud syndrome
• clinically
• occulomotor nerve dysfunction
• accompanied by ophtalmic nerve dysfunction
• optic nerve may evantually be involved
• cavernous sinus syndrome
• aka Tolosa-Hunt $
• diplopia associated with ipsilateral periorbital or hemicranial pain
• mild proptosis
• oculomotor nerve palsy

Tests carried out in patients with diplopia

Cover test
The cover test should be performed, at least initially, using an accommodative target for
fixation. Any variation in the horizontal angle of deviation with accommodative effort needs to be taken into consideration when performing ocular motility. Binocular diplopiais normally due to misalignment of the visual axes, so a movement of the deviating eye totake up fixation will be seen on occlusion of the fixating eye.
Ocular Motility

• versions
• follow finger to 6 direction
• ductions
• close 1 eye, move finger to 6 positions
• saccades
• used to test for internuclear ophtalmoplagia 

things to note

- lateral rectus palsy can be a sign of raised intracranial pressure