Scotoma: Symptoms, Types, Causes and Treatment

Scotoma is a term that may be unfamiliar to many, yet its impact on vision can be profound and life-changing. At its core, a scotoma is an area of partial alteration in the visual field—essentially, a "blind spot" or region where vision is diminished or absent. These visual field defects can arise from a variety of causes, ranging from eye diseases to neurological problems, and may come in different shapes, sizes, and severities. Understanding the symptoms, types, underlying causes, and available treatments of scotoma is essential for patients, caregivers, and clinicians alike. In this article, we will explore the spectrum of this condition in detail, providing a thorough and practical guide to one of the most significant visual field disturbances.

Symptoms of Scotoma

Scotoma symptoms can be subtle or striking, often depending on the size, location, and underlying cause of the visual field defect. For many, the experience of a scotoma begins as a nagging difficulty in daily activities, such as reading, driving, or even recognizing faces. Others may only notice issues under certain conditions, like low lighting or when focusing on small objects. Recognizing the symptoms early is key to timely diagnosis and management.

Symptom	Description	Impact	Source(s)
Blind Spot	Area of lost or reduced vision	Reading/driving issues	1,2,5
Visual Acuity ↓	Blurred or decreased sharpness	Difficulty with detail	1,2,5
Night Vision ↓	Trouble seeing in low light	Night driving problems	1
Positive Spot	Visible dark or gray area	Obstructs central view	7,5
Fixation Issues	Trouble focusing on objects	Reading, task errors	2,13
Sensitivity	Discomfort with screens/lights	Screen time problems	1

Table 1: Key Symptoms

Visual Field Defects: The Blind Spot Experience

A scotoma typically manifests as a patch or spot where vision is reduced or absent. Patients might describe seeing a dark or gray area in their line of sight, which can be especially noticeable when looking at patterned backgrounds or reading text. In some cases, the blind area is not consciously perceived, but rather noticed indirectly—such as missing words while reading or not noticing objects in specific areas of their environment 1,5,7.

Decreased Visual Acuity

Scotomas, particularly those affecting the macula (the central part of the retina), can significantly reduce visual acuity. This makes tasks requiring fine vision, like reading or distinguishing faces, particularly challenging. Studies have shown that the degree of acuity loss is related to the density and location of the scotoma 2,5.

Night Vision and Sensitivity to Light

Some patients experience increased difficulty at night, especially with driving, as the contrast between light and dark becomes more pronounced and scotomas become more noticeable 1. Sensitivity to bright lights or prolonged use of screens can also be a problem for some individuals.

Fixation and Reading Difficulties

When a scotoma encroaches on the central vision, patients may struggle to fixate on objects, leading to unstable vision and reading difficulties. This problem may be compounded in those who have not adapted to using non-affected retinal areas for fixation 2,13.

Positive versus Negative Scotomas

Some scotomas are "positive," meaning the patient perceives a dark or bright spot in their vision, while others are "negative" and only noticed by the absence of vision (i.e., missing parts of the image) 5,7.

Other Associated Symptoms

Depending on the cause, scotomas may be accompanied by other symptoms such as eye pain, headache, or neurological deficits. In cases related to infectious or systemic diseases (like dengue), patients may report sensitivity to screens, difficulty with night driving, and persistent reading problems 1.

Types of Scotoma

Scotomas are not all the same; they vary in pattern, size, and impact. Understanding their classification helps tailor diagnosis and management strategies.

Type	Characteristics	Typical Location	Source(s)
Central	Affects the center of vision	Macula/fovea	2,5,13
Paracentral	Near central vision	Adjacent to fovea	5,7
Peripheral	Affects outer visual field	Away from center	5
Absolute	Complete loss in area	Any field	4,11
Relative	Partial reduction in area	Any field	2,4,11
Positive	Dark/bright spot seen by patient	Variable	7,5
Negative	No visual perception (unnoticed)	Variable	5
Functional	No detectable organic cause	Central/paracentral	14
Bjerrum	Arc-shaped, 10-20° from fixation	Glaucoma-related	6
Junctional	Involvement at optic chiasm	Central/paracentral	9

Table 2: Scotoma Types

Central and Paracentral Scotomas

Central scotomas impair the very center of vision, often severely affecting tasks like reading and recognizing faces. Paracentral scotomas are just off-center and can be equally disruptive, especially if large 2,5,13.

Peripheral Scotomas

These affect vision at the edges or periphery of the visual field. While less likely to impact reading, they can make navigation hazardous, increasing the risk of bumping into objects or difficulty with driving 5.

Absolute vs. Relative Scotomas

An absolute scotoma is an area of complete vision loss—a true blind spot. A relative scotoma is a region where vision is partially reduced but not totally absent. The distinction is important for prognosis and rehabilitation 4,2,11.

Positive and Negative Scotomas

A positive scotoma is one the patient "sees," such as a dark or bright spot. A negative scotoma is less obvious, detected only by missing information in the visual field 5,7.

Functional Scotomas

These are visual defects without an identifiable organic lesion, sometimes seen in conditions like amblyopia or functional visual loss 14.

Bjerrum and Junctional Scotomas

• Bjerrum scotoma: Classic in glaucoma, this arc-shaped defect appears 10-20 degrees from fixation and is linked to optic nerve fiber bundle loss 6.
• Junctional scotoma: Occurs at the junction of the optic nerve and chiasm, often due to compressive lesions such as tumors or cysts 9.

Causes of Scotoma

The variety of scotomas reflects the diversity of underlying causes. These range from eye diseases to systemic illnesses and neurological disorders.

Cause	Mechanism	Common Conditions	Source(s)
Retinal Disease	Photoreceptor/RPE damage	Macular degeneration	13,11
Vascular Ischemia	Blood flow interruption	Glaucoma, hypotension	6,7
Neurological Lesions	Optic nerve/brain injury	Tumors, trauma, stroke	5,8,9
Infectious/Inflammatory	Inflammation, immune response	Dengue, uveitis	1,2
Edema	Swelling in retina	Diabetic macular edema	2
Functional	No detectable physical cause	Amblyopia, conversion	14
Degenerative	Cell death over time	Stargardt, AMD	13,11

Table 3: Causes of Scotoma

Retinal Diseases

Damage to the retina—especially the macula—can produce central scotomas. Age-related macular degeneration (AMD), Stargardt's disease, and diabetic macular edema are prime culprits. In these cases, the loss of photoreceptors or supporting cells leads directly to blind spots 2,11,13.

Vascular Causes

Any condition that impairs blood flow to the retina or optic nerve, such as glaucoma or arterial hypotension, can cause scotomas due to ischemia (oxygen deprivation). The classic Bjerrum scotoma of glaucoma is a well-known example, and transient scotomas may also occur with sudden drops in blood pressure 6,7.

Neurological Causes

Lesions affecting the optic nerve, chiasm, or visual cortex can produce scotomas. These may be due to tumors, compressive cysts (as in suprasellar arachnoid cysts), trauma, or stroke. The specific pattern of visual field loss often reflects the anatomical location of the lesion 5,8,9.

Infectious and Inflammatory Causes

Scotomas can arise after infections or inflammation of the eye, such as in dengue fever or uveitis. In a dengue epidemic, for instance, scotomas were reported as a major symptom, often persisting long after the acute illness 1. Inflammation can damage retinal or optic nerve tissue, leaving lasting field defects.

Edema and Swelling

Swelling in the retina from conditions like diabetic macular edema can disrupt vision, leading to dense or relative scotomas depending on the severity and location of the fluid accumulation 2.

Functional Scotomas

Some scotomas have no clear anatomical basis and are termed functional. These may occur in amblyopia (lazy eye) or functional visual loss, where vision is impaired despite normal eye structure 14.

Degenerative and Genetic Diseases

Inherited or age-related degeneration of retinal cells, as seen in Stargardt's macular dystrophy or AMD, can cause persistent scotomas that expand over time 13,11.

Treatment of Scotoma

Treating scotoma requires a personalized approach, depending on its cause and impact on the patient’s life. While some causes are reversible, others demand adaptation and rehabilitation strategies.

Treatment Option	Approach	Target Condition(s)	Source(s)
Medical Therapy	Steroids, immunosuppressants	Inflammatory, infectious	1,12
Laser/Photocoagulation	Retinal laser therapy	Macular degeneration	10,11
Surgery	Cyst/tumor removal	Compressive lesions	9
Vision Rehabilitation	Training, low vision aids	Central scotoma, AMD	13
Microperimetry-guided	Eccentric fixation training	Central field loss	13,11
Functional Therapy	Orthoptic/terahertz therapy	Functional scotoma	14
Disease Management	Control underlying disease	Diabetes, hypertension	2,6,7

Table 4: Treatment Approaches

Medical Therapies

For scotomas resulting from inflammation or infection (such as dengue-related ocular complications), systemic corticosteroids or immunosuppressants may reduce swelling and limit permanent damage 1,12. Early intervention is crucial to prevent long-term sequelae.

Laser and Photocoagulation Therapy

Laser treatments, such as photodynamic therapy or scotoma-based photocoagulation, can stabilize or reduce the progression of scotomas in conditions like AMD and diabetic macular edema. These therapies aim to address abnormal blood vessels or retinal damage 10,11.

Surgical Intervention

When scotomas are due to compressive lesions—such as tumors or cysts—surgical removal can result in significant recovery of visual function, even reversing the scotoma if performed in time 9.

Vision Rehabilitation

For irreversible scotomas, rehabilitation becomes key. Techniques include:

• Eccentric fixation training: Teaching patients to use unaffected parts of the retina to compensate for central vision loss 13.
• Low vision aids: Magnifiers, special glasses, and electronic devices help maximize remaining vision 13.

Microperimetry and Fixation Training

Using technologies like fundus microperimetry, clinicians can assess fixation patterns and train patients to move their gaze away from the scotoma, often resulting in measurable improvements in function, even if the scotoma itself expands 13,11.

Functional and Orthoptic Therapy

Functional scotomas, particularly in amblyopia or cases without organic cause, may respond to pleopto-orthoptic treatments and terahertz therapy, which have been shown to enhance visual acuity and eliminate the scotoma in some patients 14.

Disease Control and Prevention

Managing the underlying systemic disease is critical. This may include:

• Tight glucose control in diabetes to prevent macular edema 2.
• Blood pressure management in vascular-related scotomas 6,7.

Conclusion

Scotoma represents a complex and multifaceted visual field defect that can arise from a wide array of ocular and systemic conditions. Early recognition, accurate classification, and a tailored treatment approach offer the best chance for preserving vision and quality of life.

Key Takeaways:

• Scotomas present as blind spots or areas of reduced vision, impacting daily activities like reading and driving.
• Types include central, peripheral, absolute, relative, positive, negative, functional, Bjerrum, and junctional scotomas.
• Causes range from retinal diseases (like AMD and diabetic macular edema), vascular events, neurological lesions, inflammation, to functional disorders.
• Treatments vary widely and may include medical therapy, laser or surgical intervention, rehabilitation, and advanced therapies like microperimetry-guided training.
• Vision rehabilitation and adaptation are essential when scotomas are irreversible, empowering patients to maximize their remaining vision.

If you or someone you know is experiencing changes in vision or blind spots, prompt evaluation by an eye care professional is essential. Early detection and intervention can make a significant difference in managing scotoma and preserving quality of life.