Diplopia Flashcards
What is diplopia?
Double vision.
Diplopia is a common complaint in medical practice. It may be monocular or binocular. An understanding of the anatomy of the eye, external ocular muscles and their innervation is essential to approach diagnosis of the cause.
What is binocular diplopia?
This occurs when the images produced by the two eyes do not absolutely match, so that the images produced are misaligned relative to one another. The diplopia disappears when one eye is covered.
What is monocular diplopia?
This is much less common. It affects one eye only and continues when the unaffected eye is covered. It can be caused by abnormalities of the lens, cornea or retina, which result in splitting of the image.
What are the causes of diplopia?
Cornea and lens problems
Eye muscle disorders
Nerve problems
Brain problems
What are examples of cornea and lens problems resulting in diplopia?
This leads to production of unequal images.
These include refractive errors, keratoconus, cataracts, corneal scarring, subluxation and herpes zoster. Dryness of the cornea can occasionally cause double vision.
What are examples of eye muscle disorders resulting in diplopia?
Myasthenia gravis
Grave’s disease
Myotonic dystrophy
Muscles such as inferior rectus may be trapped during basal orbital fracture.
Convergence insufficiency (treated with glasses, eye exercises or prisms)
What are examples of nerve problems resulting in diplopia?
Problems affecting the nerve that control the eye muscles.
MS, GBS and DM.
Temporary palsy from Lyme disease, GCA, DM and HTN.
Nerves trapped in traumatic fracture of the orbital bones.
What are examples of brain problems resulting in diplopia?
Strokes Aneurysms Space occupying lesions Migraine Causes of raised ICP -Raised ICP affects CNVI more as it has the longest intracranial course. Alcohol intoxication Concussion Side effects of phenytoin, lamotrigine, opioids, zolpidem and ketamine.
How does diplopia present?
Diplopia presents either with a complaint of double vision or the observation of squint.
Paralysis of a muscle means that the eye will not move fully in the direction in which it pulls. At rest, when the other muscles are unopposed, the eye may therefore deviate in the opposite direction from the pull of the affected muscle.
Diplopia may occur alone or in conjunction with other symptoms such as pain on eye movement, pain around the eyes, ptosis, headache or nausea.
The patient will often complain of double vision. Images may overlap or be adjacent. It is helpful to ask about image alignment, whether they appear (or worsen) on a particular direction of gaze, and whether they are intermittent or constant.
It is also helpful to find out if the double vision disappears on closing one eye, and whether both images are in focus.
What are the signs associated with diplopia?
Check for ptosis which is often the first sign of weakness and eyelid elevation is partly controlled by CN III
Check the light reflex
Fundoscopy to rule out papilledema
Attempt to identify which eye is affected and which direction of gaze is limited. This will allow determination of which structures are likely to be involved. Examine the alignment of the eyes in various head positions and on looking in every direction.
Note whether one eye seems to be deviated. Isolated palsy of only one of the muscles supplied by the oculomotor nerve is unusual.
What are the causes of diplopia?
Abducens nerve palsy as seen in space-occupying lesion and DM. Psychosomatic- inconsistency of hx and unusual elements such as monocular double vision in both eyes. Tiredness can cause transient diplopia. Myasthenia gravis Parkinson's disease Encephalopathy Progressive supranuclear palsy Sepsis Ophthalmoplegic migraine is a rare cause. GCA is another rare cause. Sarcoidosis CJD
What are the red flags of diplopia?
Pupil involvement with third nerve palsy: large poorly reactive pupil with diplopia is the most common presentation of an aneurysm of the posterior communicating artery.
Diplopia affecting two or more of lip, pupil and eye movement. This may suggest isolated third nerve palsy (as above), Horner’s syndrome (small pupil and ptosis) due to carotid dissection, or inflammatory neuropathy (Guillain-Barré syndrome).
Multiple cranial nerve palsies: this suggests intracranial or meningeal tumour, polyneuropathy or cavernous sinus lesion.
Diplopia with weakness or fatigue: suggests myasthenia gravis.
Diplopia with new-onset headache and scalp tenderness: suggests giant cell arteritis.
What are the investigations done for diplopia?
Before referral, check for diabetes (if it is not already diagnosed) and check blood pressure in case of hypertension.
MRI scan may show a tumour, an area of infarction or even an arterial aneurysm pressing on a nerve. It can also show demyelination.
CXR may reveal malignancy or sarcoidosis.
Other specialist investigations may be offered depending on the suspected cause.
Isolated cranial nerve palsies in patients with diabetes and hypertension do not usually need investigation unless they progress or fail to resolve over time.
Multiple nerve palsies are usually imaged, as are isolated nerve palsies in patients aged under 50 years without a long history of vasculopathy.
What is the management of diplopia?
People with diplopia must not drive. They may resume driving on confirmation to the licensing authority that the diplopia is controlled by glasses or by a patch which the licence holder undertakes to wear whilst driving. There will probably be permanent revocation of an LGV or PCV licence.
Exceptionally, a stable uncorrected diplopia of six months’ duration or more may be compatible with driving if there is consultant support indicating satisfactory functional adaptation.
Diplopia (seeing double) can be very distressing.
All patients should be referred to an orthoptist (an orthoptist is an allied health professional who can investigate, diagnose and treat defects of binocular vision and abnormalities of eye movement)
In the first instance a patient may just simply choose to patch their eye – this will allow the brain to receive only one image.
If the patient wears spectacles, a temporary prism – fresnel prism, can be fitted and the power adjusted as the palsy resolves.
If a patient is left with residual diplopia, permanent prisms in their glasses can be considered or surgical intervention to realign the eyes.
What is oculomotor nerve palsy?
Oculomotor nerve palsy is a condition resulting from damage to the oculomotor nerve. The most common structural causes include:
- Raised intracranial pressure (compresses the nerve against the temporal bone).
- Posterior communicating artery aneurysm
- Cavernous sinus infection or trauma.
- Note: there are other pathological causes of oculomotor nerve palsy such as diabetes, multiple sclerosis, myasthenia gravis and giant cell arteritis.
