Diplopia generally known as double vision. Do you see double images sometimes? Excluding the self-made squinting of eye, Getting drunk on those weekends, and tired Mondays, this sort of short timed diplopia is not a thing to worry about.
The term diplopia is derived from Greek word Diplous means Double and Ops means eye.
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What is diplopia?
Our two eyes work mutually; the images that hit the fovea are processed by the brain. Thus the term binocular single vision is used. In the absence of simultaneous perception of light from the same object, the binocular single image is not formed. It is the result of impaired function of Extraocular Muscles to fixate the target of the normally functioning eyes, to the object of desire. Problem with the extraocular muscle could be Mechanical (Trauma & Injury), Disorder of Motor neuron- Muscle junction (myoneural junction), Disorders of trochlear, Abducens, & Oculomotor cranial Nerve.
ICD-10 code for Diplopia is H53.2. It’s medical classification as listed by World Health Organization under the range – Diseases of the eye and adnexa .
There are main two types of double vision that are monocular diplopia and binocular.
This happens as a result of misalignment of the two eyes, that is the eyes turned inwards (clinically termed as esotropia) and eyes turned out (exotropia). The fovea of one eye is facing opposite to other eyes. The image reaching the fovea are different. This results in visual confusion. The brain helps by suppression of the one eye to protect diplopia. The suppression is mostly seen in childhood when a child has “strabismus”. This is why child never complains of diplopia. But this can result in amblyopia and Visual Impairment. Adults sometimes adapt to suppress one eye due to regular diplopia.
The double vision seen only when viewing with one eye is a rare case seen in patients. Differential diagnosis is Keratoconus, lens subluxation, a lesion in the anterior visual cortex.
Other Types of Double vision
It is caused by alcohol intoxication, head injuries, patient under medications like opioids, the anti-epileptic drugs, the anti-epileptic drugs, the hypnotic drug, the dissociative drugs, tired eye muscles can also cause diplopia.
This is done for the fun purpose mostly and is a voluntary act. while seeing objects too close to the eye, double objects are seen. Placing a finger in front of the visual field while being viewing tv screen, the finger causes the diplopia.
Causes for double vision
Keratoconus cause the light entering the eye to diffract and scatter all over the retina. Corneal dystrophies too cause the appearance of ghost images.
Sjogren’s syndrome(Severe Dry Eye)
Due to the insufficiency of the tear film over the corneal surface, the light scatters as soon as it touches the corneal epithelium.
Stroke, head injury, brain tumour, brain swelling or a brain aneurysm
A head injury, tumour, stroke or related condition can cause double vision that comes on suddenly. After examining you, your eye doctor may refer you to a specialist such as a neurologist or neurosurgeon for further testing and treatment.
LASIK, PRK, and other refractive surgery is done to help you see better without the help of glasses or contact lenses. The change in corneal shape or dryness causes the appearance of the Ghost image.
Anterior chamber cells/Keratic precipitates
As light enters the eye, The tiny cells particles block the light. The light is scattered in the anterior chamber. Patients with uveal tissue inflammation have ac cells all over the anterior chamber.
Cataract cause the light to disperse due to its density. The light dispersion happens as soon as the light touches the natural crystalline lens.
Cranial nerves palsies:
- 3rd nerve i.e. Oculomotor nerve which stimulates Superior Rectus, Inferior rectus, medial Rectus, Inferior oblique.
- 4th nerve i.e. Trochlear nerve controls a superior oblique muscle.
- 6th nerve i.e. Abducens nerve controls Lateral Rectus. Thus restriction of the muscles causes the diplopia.
Note: Patients with cataract operated could see double vision due to the presence of posterior capsular opacity behind the artificial intraocular lens implanted and other causes like wearing of prescription glasses in a wrong way leads to multiple image formation. Thus, Spectacles can be reason for diplopia and headache. Diplopia has a diverse range of ophthalmologic, infectious, autoimmune, neurological, and neoplastic causes.
Test for double vision
For effective management of the diplopia various ophthalmic investigations and neurological investigation will be made. The test for double vision will help to rule out the types and causes of double vision.
Some of common test done in eye hospital for diplopia are as follows.
- Hirschberg test (corneal light reflection test): To demonstrate the degree of diplopia and to document.
- Diplopia charting
- Cover test (Unilateral and Alternating cover test)
- Maddox Rod Test
Your eye doctor may performs following tests for Diplopia assessment
- Visual acuity test for distance and near vision
- Versions ( pursuits, saccades & muscle overaction)
- Convergence test
- Ocular alignment (muscle balance)
- Pupillary examination
- Lid function test
- Vestibulo ocular reflex (Dolls eye reflex)
- Bells phenomenon
- Prism measurements
- Optokinetic nystagmus (OKN)
Treatment of Diplopia
Treatment of temporary causes is not necessary. But, If the problem persists again, you have to visit your nearest eye hospital. Ophthalmologists or optometrist will begin the treatment of the underlying root cause. It’s important to have a comprehensive eye exam to help determine the cause of the double vision as soon as possible.
Treatment of double vision depends upon the underlining causes, some of treatment will be made such as:
Double vision due to the dry eye conditions should be treated with the frequent installation of an artificial tears eye drops.
To determine the neurological causes, your eye doctor may then treat the double vision or send you to a specialist (such as a neurologist or neurosurgeon). If there is diplopia due to tumor in the brain the treatment of brain tumours is needed.
Cranial nerve palsies can be caused by diabetes, head injury, tumour, multiple sclerosis, meningitis, high blood pressure, blockage of an artery or an aneurysm. Most cranial nerve palsies go away without treatment when the condition that caused them improves.
Double vision due to Keratoconus, cataract, corneal dystrophies, astigmatism, strabismus (Squint) need surgical correction or correction with and contact lens, eyeglasses or by using prisms.