Diplopia: Symptoms, Types, Causes and Treatment

Diplopia, commonly known as double vision, is a condition where a person sees two images of a single object. This experience can be alarming and disruptive to daily life. Understanding the symptoms, types, underlying causes, and available treatments is crucial for both patients and healthcare providers. In this article, we’ll provide a comprehensive overview of diplopia, synthesizing insights from research and clinical studies to offer a detailed, evidence-based guide.

Symptoms of Diplopia

Diplopia presents itself in ways that can range from subtle to severely disabling. Recognizing the right symptoms is the first step toward prompt and accurate diagnosis, helping to distinguish between harmless and potentially serious underlying conditions.

Symptom	Description	Associated Features	Source(s)
Double Vision	Seeing two images of a single object	May be side-by-side, above-below, or tilted	1 5 4
Blurred Vision	Objects appear less clear along with double vision	Often co-occurs with other visual disturbances	2 6
Visual Hallucinations	Perception of things that are not present	Linked with neurological causes, e.g., PD	2 6
Eye Pain	Discomfort or pain in/around the eyes	Suggests infection, inflammation, or trauma	4
Headache	Pain in the head, often with visual loss	May indicate a neurological emergency	4
Ptosis	Drooping of the upper eyelid	Can be associated with nerve or muscle disease	4 12

Table 1: Key Symptoms

Double Vision: The Defining Symptom

The hallmark of diplopia is the perception of two images of a single object. The orientation of these images—side-by-side, vertically displaced, or even tilted—can offer crucial clues about the underlying problem. For example, sixth nerve palsies often produce side-by-side images, while fourth nerve palsies result in one image appearing tilted above the other 4 5.

Associated Visual Disturbances

Patients may also experience blurred vision, light sensitivity, or problems with spatial perception. In neurological conditions like Parkinson’s disease, diplopia can co-occur with visual hallucinations or other positive visual phenomena 2 6. These associated symptoms can help clinicians distinguish between purely ocular versus neurological causes.

Pain and Other Red Flags

The presence of pain with double vision is an important diagnostic clue. Pain often points to infectious or inflammatory causes, whereas painless diplopia may be more likely due to vascular, tumorous, or degenerative conditions 4. Headaches, especially when accompanied by visual loss, should be considered a red flag, warranting urgent evaluation for possible neurological emergencies 4.

Additional Symptoms

Other signs such as ptosis (drooping eyelid) or pronounced eye movement abnormalities can further aid in narrowing down the diagnosis. Ptosis is seen in conditions like myasthenia gravis and sagging eye syndrome, as well as in certain cranial nerve palsies 4 12.

Types of Diplopia

Understanding the types of diplopia is critical, as it shapes both diagnosis and management. The main division is between monocular and binocular diplopia, each with distinct implications.

Type	Key Characteristic	Common Causes	Source(s)
Monocular	Persists with one eye closed	Ocular pathology	1 5 10
Binocular	Resolves when either eye is closed	Eye misalignment	1 5 8 9
Central-Peripheral Rivalry (CPR)	Double vision due to retinal misregistration	Epiretinal membranes, retinal disease	7 10
Functional	No identifiable structural cause	Rare, diagnosis of exclusion	5

Table 2: Types of Diplopia

Monocular Diplopia

Monocular diplopia persists when only one eye is open and is almost always due to a problem within that eye itself, such as refractive errors, cataracts, or corneal irregularities. It is not caused by abnormalities of eye alignment or neurological disease 1 5 10. These cases require a thorough ophthalmological assessment.

Binocular Diplopia

Binocular diplopia disappears when either eye is covered and is caused by misalignment of the visual axes. It is typically due to problems in the eye muscles, the nerves controlling them, or the structures supporting the eyes. Binocular diplopia is much more common than monocular diplopia, especially in older adults 1 8 9.

Central-Peripheral Rivalry (CPR) Diplopia

A specialized subtype, CPR-type diplopia, results from retinal misregistration, often due to diseases like epiretinal membrane. This type can be mistaken for other forms but is distinguished by unique clinical tests and is important due to its specific management strategies 7 10.

Functional Diplopia

Rarely, diplopia can be functional—without any detectable structural or neurological cause. This diagnosis should only be made after exhaustive evaluation has excluded all other possibilities 5.

Causes of Diplopia

The causes of diplopia are diverse, ranging from benign ocular issues to life-threatening neurological emergencies. A systematic approach is vital for accurate diagnosis.

Cause Category	Examples/Details	Age/Population Most Affected	Source(s)
Ocular Pathology	Cataract, corneal disease, refractive error	All ages (monocular)	1 5 10
Cranial Nerve Palsy	3rd, 4th, 6th nerve palsies	Older adults, vascular risk	1 3 4 8
Muscle Disorders	Myasthenia gravis, thyroid eye disease	Middle-aged/older adults	8 11 13
Orbital Lesions	Tumors, trauma, inflammation	All ages	1 4 8 11
Sagging Eye Syndrome	Connective tissue degeneration	Elderly, more common in women	9 12
Vascular Events	Microvascular ischemia, stroke	Elderly, vascular risk factors	8 11
Decompensated Phorias	Latent misalignments becoming manifest	Children, young adults	1 8 11
Retinal Causes	Epiretinal membrane, CPR-type diplopia	Middle-aged/older adults	7 10
Neurologic Disease	Parkinson’s, multiple sclerosis	Variable	2 3 6 8

Table 3: Common Causes of Diplopia

Ocular Pathology

Monocular diplopia is most often due to ocular problems such as cataracts, corneal disease, or refractive errors. These issues distort the way light enters the eye, leading to the perception of double images 1 5 10.

Cranial Nerve Palsies

The most common cause of acute binocular diplopia is palsy of one of the cranial nerves that control eye movement (III, IV, VI). These can be due to microvascular ischemia, trauma, tumors, or demyelinating diseases. In older adults, microvascular causes linked to diabetes and hypertension predominate 1 3 4 8 11.

Muscle and Neuromuscular Junction Disorders

Diseases affecting the eye muscles, such as myasthenia gravis and thyroid eye disease (Graves orbitopathy), can impair eye movement and lead to diplopia. These tend to affect middle-aged and older adults 8 11 13.

Sagging Eye Syndrome (SES)

A leading cause of non-paralytic binocular diplopia in older adults, SES results from degeneration of the connective tissues supporting the extraocular muscles. It is particularly common in elderly women and often presents as small-angle strabismus, either esotropia (inward turning) or hypertropia (vertical deviation) 9 12.

Vascular and Traumatic Causes

Vascular events (such as microvascular ischemia or stroke) and trauma are significant causes, especially in older adults and those with vascular risk factors. Trauma is a more common cause in younger adults 8 11.

Decompensated Phorias

Latent strabismus (phoria) can become manifest (tropia) under stress, fatigue, illness, or with age, resulting in diplopia. This is more common in children and young adults, but can occur at any age 1 8 11.

Retinal and Central Causes

Retinal disorders, particularly epiretinal membrane, can cause diplopia via central-peripheral rivalry. Neurological diseases such as Parkinson’s disease can also present with diplopia, often accompanied by other visual and perceptual disturbances 2 3 6 7 10.

Treatment of Diplopia

Diplopia management is highly individualized, depending on the type, underlying cause, and the patient’s daily needs. The goal is always to restore single, comfortable vision and improve quality of life.

Treatment	Mechanism / Approach	Common Indications	Source(s)
Ocular Occlusion	Patching or frosted lens to block input	Intractable or temporary diplopia	16
Prism Glasses	Shift images to align on retina	Mild-moderate misalignment	7 16
Monovision Correction	Corrects vision in one eye only	Small-angle deviations, presbyopia	15 16
Strabismus Surgery	Realigns eye muscles	Large or stable misalignment	9 12 13 16
Chemodenervation	Botulinum toxin to weaken overactive muscle	Select cases of strabismus	16
Treat Underlying Disease	Medical management (e.g., Graves, myasthenia)	Disease-specific	13 14
Retinal Surgery	ERM peeling for CPR-type diplopia	Retinal misregistration	7 10

Table 4: Treatment Strategies

Non-Surgical Treatments

Ocular Occlusion: Using a patch or frosted lens can provide immediate relief by preventing the brain from registering double images. This is often used as a temporary solution or for patients who are not candidates for other treatments 16.

Prism Glasses: Prisms incorporated into eyeglasses can align the images seen by both eyes, effectively correcting mild to moderate misalignment. Fresnel prisms are often used for temporary or diagnostic purposes, while ground-in prisms are suitable for permanent correction 7 16.

Monovision Correction: For small-angle diplopia, particularly in presbyopic patients, monovision (correcting only one eye for distance vision) can significantly reduce symptoms and improve quality of life 15 16.

Surgical Treatments

Strabismus Surgery: Surgical realignment of the eye muscles is indicated for large or stable deviations, or when non-surgical options fail. Success rates are high for conditions like sagging eye syndrome and Graves orbitopathy, especially when tailored techniques and adjustable sutures are used 9 12 13.

Retinal Surgery: In CPR-type diplopia due to epiretinal membrane, surgical peeling of the membrane can resolve symptoms in a significant proportion of patients 7 10.

Treating Underlying Disease

For diplopia caused by systemic diseases, addressing the root cause—such as immunosuppressive therapy for myasthenia gravis or thyroid eye disease—is essential. Ongoing collaboration between ophthalmology, neurology, and other specialties is often required 13 14.

Chemodenervation

Botulinum toxin injections can temporarily paralyze overactive muscles, helping to correct misalignment in select cases where surgery is not indicated or as a bridge to surgery 16.

Conclusion

Diplopia is a multifaceted symptom with a spectrum of underlying causes and treatment options. Accurate diagnosis depends on careful symptom assessment and distinguishing between the various types. Treatment is tailored to the individual and the underlying etiology, ensuring the best possible visual outcome.

Key Takeaways:

• Diplopia manifests as double vision, sometimes with blurred vision, pain, or other visual disturbances.
• Types include monocular (ocular causes), binocular (misalignment), and rarer subtypes like CPR-type diplopia.
• Causes range from eye disorders and nerve palsies to systemic and neurological diseases; sagging eye syndrome is a leading cause in older adults.
• Treatment options include occlusion, prisms, monovision, surgery, and disease-specific management, chosen based on the underlying cause and patient needs.

Early recognition and multidisciplinary management are essential for optimal care and restoring quality of life for individuals experiencing diplopia.