H53.2 Diplopia

Diplopia occurs when an object is seen in two subjective visual directions.  Patients usually report that “I see double.”

The natural history of diplopia depends upon the cause.  Diagnosis and treatment of the condition requires basic knowledge in neuroanatomy, ocular motility, visual fields, optics and internal medicine.

Common causes of diplopia include the following.

• Cranial nerve disease
• Thyroid eye disease
• Myasthenia gravis
• Internuclear ophthalmoplegia
• Optical

Ocular motility problems caused by cranial nerve disease is the most common cause of acute binocular diplopia.

The main goal of the diagnostic evaluation in a patient with diplopia is to accomplish the following: 

• To establish whether the diplopia is monocular or binocular
• To determine if the diplopia is constant or intermittent
• To determine if the diplopia is present at distance, near or both
• To determine the direction of the diplopia (horizontal, vertical or torsional)
• To determine the duration of the diplopia
• To determine the stability of the diplopia

To obtain the information required to determine a clinical diagnosis of diplopia and to prescribe a treatment plan, the following service components of a medical eye examination should be performed. 

• Patient history
• General medical observation
• Gross general fields
• Basic sensorimotor examination
• Adnexal examination
• External ocular examination with biomicroscopy
• Ophthalmoscopy

Patient History

Patients with diplopia may present with any of the following abnormal clinical symptoms:

• Double vision 
• Blurred vision
• Headache

Diplopia is classified into four important types:

• Binocular diplopia is an eye movement disorder that occurs in both eyes. When covering one eye the binocular diplopia it disappears. Binocular diplopia is caused by diabetes, strabismus, trauma to the eye muscles, myasthenia gravis, grave’s disease and damage to nerves controlling the extraocular muscles. 
• Monocular diplopia is affecting one eye and it continues even when the other eye is covered. It can be caused by astigmatism, cataracts, keratoconus, pterygium, retinal problems, a dislocated lens, dry eye, a mass of swelling in the eyelid.
• Temporary diplopia usually is caused by concussions, head injuries or alcohol intoxications. It could also come as a side effect of certain drugs like anti-convulsant (Lamotrigine), dissociative drugs (Dextromethorphan, Ketamine), anti-epileptics (Zonisamide, Phenytoin) and hypnotics (Zolpidem). It could also be caused by tired or strained muscle. 
• Voluntary diplopia is when a person can uncouple their eyes and have double vision at will.

All of the following conditions can produce symptoms of diplopia:

• Abducens nerve palsy
• Amblyopia
• Aniridia
• ARMD, nonexudative
• Astigmatism, astigmatic keratotomy
• Astigmatism, LASIK
• Botulism
• Brown syndrome
• Cataract, senile
• Cataract, traumatic
• Cellulitis, orbital
• Chronic Progressive External ophthalmoplegia
• Contact lens complications
• Convergence insufficiency
• Corneal topography and imaging
• Duane syndrome
• Ectopia lentis
• Epimacular membrane
• Esotropia
• Exophthalmos
• Exotropia
• Extraocular muscles, actions
• Extraocular muscles, anatomy
• Foreign body, intraocular
• Headache, children
• Headache, migraine
• Hemangioma, cavernous
• Herpes zoster
• Hyperopia 
• Idiopathic intracranial hypertension
• Intraocular lens decentration
• Intraocular lens dislocation
• Keratoconus
• Laceration, corneoscleral
• Meningioma, sphenoid wing
• Monofixation syndrome
• Multiple sclerosis
• Myasthenia gravis
• Myopia
• Oculomotor nerve palsy
• Orbital fracture
• Pellucid marginal degeneration
• Pituitary apoplexy
• Pterygium
• Scleritis
• Thyroid ophthalmopathy
• Trochlear nerve palsy
• Tumors, orbital
• Wernicke encephalopathy
• Wilson disease

Medical Care

• Patching one eye — Patching is often required, since the patient has to continue functioning while awaiting resolution or intervention
• Stick-on occlusive lenses can be applied to eyeglasses to minimize the cosmetic handicap of a patched eye, while sufficiently blurring the one eye to minimize disabling double vision
• Fresnel prisms — These prisms can be pressed on to eyeglasses.  Although these prisms are only appropriate if a stable deviation is present across all directions of gaze, they severely blur the image from that eye and function in many ways like an occlusive lens.
• Treatment of myasthenia gravis — Mestinon or other long-acting anticholinergic agent, as well as corticosteroids, may be required.

• Strabismus surgery is occasionally necessary.  The typical recession/resection is rarely indicated due to the one muscle often being permanently weak, and any standard surgery will lose effect over time.  Exceptions include a blow-out fracture when the release of the entrapped soft tissues from the fracture in the floor of the orbit can be very effective.
• Transposition surgery (Hummelsheim surgery) — With permanent paralysis of the lateral rectus muscle, overcoming the unopposed tone of the medial rectus muscle is possible by splitting the superior and inferior recti muscles and by reinserting the lateral half of each muscle at the lateral rectus insertion.  Otherwise, any recession of the medial rectus muscle will be of only temporary benefit. Despite achieving single vision straight ahead, the diplopia will persist with gaze toward the paralytic muscle.
• Knapp superior oblique muscle paralysis — With permanent weakness of the superior oblique muscle, it is possible to weaken the yoke muscle of the opposite eye (superior rectus muscle) as well as the direct antagonist (inferior oblique muscle) in the same eye, together with a shortening of the affected muscle, to minimize the deviation.
• Chemodenervation — This helps prevent the contracture in eyes with extraocular muscle paresis, especially when return of function is expected. Multiple injections over several months of botulinum toxin into the medial rectus muscle reduce contracture due to a weak lateral rectus from a sixth nerve paralysis.  The effect may be more permanent than expected; the opposing un-injected muscle may develop a degree of permanent shortening and contracture.

Consultations

• Diabetologist — Isolated cranial nerve weakness (e.g., typically third or sixth cranial nerve) indicates a microangiopathy of diabetes.  A review of the appropriateness of diabetic control is indicated.
• An endocrinologist specializing in thyroid disorders may be required to control the metabolic disorder associated with severe Graves disease.
• An ear, nose, and throat (ENT) specialist may be required for sinus diseases and blow-out fractures.
• A neurologic or neurosurgical opinion may be beneficial to evaluate cranial nerve palsies.

Activity

1.  Girgis N.  The diagnosis behind diplopia.  RevOptom.  15 Aug 2008; (8): 80-86. http://www.revoptom.com/content/d/patient_care/i/807/c/15063/.  Last accessed August 18, 2014.
2.  Gray LG.  Doctor I see double.  RevOptom.  Mar 1985; (3): 41-49.