What Is Scotoma

  • Samreen Noman Master's degree, Biomedical Sciences, General, Bonn-Rhein-Sieg University of Applied Sciences, Germany
  • Ananya Dangra BSc Biomedical Science, King's College London

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Let's discuss scotoma, a visual anomaly causing blind spots or distortions. 

Here, we confidently unravel the intricacies of scotoma, providing the answers you seek about this intriguing aspect of vision. 

Introduction

Definition of scotoma

Scotoma is a term used in ophthalmology and neurology to describe a type of visual impairment characterised by regions of reduced or lost vision within the eye.

These regions, also known as blind spots or distortions, can impair central or peripheral vision and suggest an impairment in the normal processing of visual information.

Scotomas can result from a variety of underlying reasons, such as optic nerve abnormalities, retinal problems, or even neurological disorders. 

Understanding the physiology of scotoma is critical for both medical professionals and those suffering from vision problems, as it serves as the foundation for accurate diagnosis and therapeutic options.1

Importance of Understanding Scotoma

Impact on vision and perception

Scotoma has a significant impact on vision and perception, impacting how people perceive and interact with their visual surroundings. 

Scotoma causes blind spots or distorted areas within the visual field, which can impair one's ability to see fully. 

Activities such as reading or recognising faces may be especially difficult in situations with central scotoma, which affects the central vision. 

Peripheral scotoma, on the other hand, might make it difficult to notice objects or movement at the margins of vision. 

This limitation not only has a functional impact on daily life, but it also has emotional and psychological consequences, as individuals may struggle with the constraints inflicted on their optical perceptions.

Relevance to various medical conditions

Scotoma is relevant across a wide range of medical disorders, acting as both a signal and a result of underlying health difficulties. 

It is frequently used as a warning sign in glaucoma, macular degeneration, and diabetic retinopathy, where reduced blood flow or injury to the optic nerve can lead to the development of blind patches. 

Furthermore, scotomas have been connected to neurological diseases such as migraines, in which visual abnormalities may precede or accompany headaches. 

Understanding the relationship between scotoma and a variety of medical disorders is critical for healthcare practitioners since it allows for early detection and targeted therapies.

Types of scotoma

Central scotoma

Definition and characteristics

A central scotoma is a form of vision impairment that is distinguished by a blind or obstructed area in the centre of the visual field.1 

It is, in essence, a localised blind spot that has a direct impact on central vision. 

This visual aberration is frequently connected with diseases of the macula, a vital region of the retina that produces sharp, detailed vision. 

As a result, people with central scotomas may struggle with activities that require intense vision in the centre, for instance reading or recognising faces. 

The features of a central scotoma emphasise its importance in comprehending the delicate nuances of vision, as it emphasises the centre visual field's vulnerability to diverse ocular diseases.

Common causes

Central scotomas can result from a number of underlying reasons, each of which leads to central visual impairment. 

  1. One popular reason is age-related macular degeneration (AMD), a degenerative disorder that affects the macula and results in central vision degradation.2
  2. Macular edema, a disorder characterised by the buildup of fluid in the macula, causes distortion or a blind spot in the centre of the visual field, is another common culprit.3
  3. Central scotomas can also be caused by disorders such as Stargardt's disease, which causes the macula to gradually deteriorate.4
  4. Optic nerve diseases, especially those involving the optic disc, may give rise to central scotomas. 

Recognising these prevalent origins is critical for successfully identifying and managing central scotomas, allowing for focused therapies and preservation.

Summary

Central scotoma: 

Definition and Characteristics: Impairs central vision, frequently resulting in blind spots or distortions.

Common Underlying Cause: Linked to macula problems such as age-related macular degeneration (AMD).

Peripheral scotoma

Definition and characteristics

The peripheral scotoma is characterised as a region of degraded or lost vision near the visual field's border. 

Peripheral scotomas, as opposed to central scotomas, appear as blind spots or abnormalities in the peripheral vision. 

These visual abnormalities are frequently caused by illnesses affecting the outside of the retina or optic nerve. 

Peripheral scotomas can cause a decreased capacity of recognising items or changes in the peripheral vision, which can interfere with tasks like navigating through crowded environments or engaging in activities that require awareness of surroundings.5

Common causes

Peripheral scotomas can result from a variety of common reasons that impact the visual system's periphery regions. 

  1. One common cause is retinal detachment, which occurs when the retina moves off from its usual position, causing visual abnormalities in the peripheral vision.6
  2. Glaucoma, a disorder characterised by high pressure inside the eye that may lead to optic nerve injury and subsequently peripheral vision loss, is another prominent reason.7
  3. Retinitis pigmentosa, a hereditary condition that causes progressive retinal degeneration, is also linked to peripheral scotomas.8
  4. Blind spots in the peripheral vision field can also be caused by illnesses such as choroiditis or other neurological abnormalities. 

Recognising these frequent causes allows healthcare practitioners to undertake extensive examinations, allowing for early detection and personalised therapies to address the underlying causes.

Summary

Peripheral scotoma:

Definition and characteristics:  Appears as blind spots or distortions at the outer boundaries of the visual field.

Common underlying causes: Retinal detachment, glaucoma, and retinitis pigmentosa are all linked to this disorder.

Absolute scotoma

Definition and characteristics

Absolute scotoma is a form of vision impairment characterised by a complete loss of sight in one area of the visual field.1

In contrast to other types of scotomas that may feature partial loss or distortions, absolute scotomas indicate a complete lack of visuals in the affected region. 

These scotomas are frequently linked with specific pathologies, such as optic nerve lesions or retinal defects, and their presence can have a significant impact on visual function, necessitating a comprehensive evaluation and treatment.

Common causes

Absolute scotomas, which are defined by a complete lack of vision in particular locations, could result from a variety of underlying causes: 

  1. One prevalent factor is optic nerve injury, which is typically caused by disorders such as optic neuritis, ischemic optic neuropathy, or optic nerve compression. 
  2. Absolute scotomas can also be caused by retinal illnesses such as retinal detachment or significant retinal degeneration.2
  3. Vascular problems affecting the supply of blood to the nerve that supplies vision or retina may play a role in the development of these total blind patches in some circumstances.
  4. Furthermore, certain inflammatory disorders affecting the visual pathways or significant eye injuries can result in absolute scotomas.

Summary

Absolute scotoma: 

Definition and Characteristics: represents a total absence of eyesight in an identified area.

Common underlying causes: Usually occurs as a result of severe optic nerve damage, retinal abnormalities, vascular problems, or substantial trauma.

Relative scotoma

Definition and characteristics

A relative scotoma is a type of visual impairment that causes a partial or relative loss of vision in one area of the visual field.1

In contrast to absolute scotomas, which include a complete loss of vision, relative scotomas involve a decrease in perception in the affected region. 

Rather than a complete blind spot, the characteristics of relative scotomas sometimes emerge as an area of lower clarity or increased difficulty perceiving visual information. 

These scotomas can be caused by a variety of reasons, including minor retinal or optic nerve impairment. 

In relative scotomas, the contrast between normal vision and the affected area is subtler, necessitating extensive visual assessment. 

Common causes

Relative scotomas, or partial blindness, can result from a variety of common factors that impair the visual system. 

  1. Refractive errors, such as nearsightedness or farsightedness, are a common contributor, as they can cause areas of diminished visual acuity in specific parts of the visual field.9
  2. Retinal abnormalities, such as macular degeneration or diabetic retinopathy, are another prevalent cause, with localised malfunction leading to relative scotomas.
  3. These partial vision deficits can also be caused by optic nerve abnormalities such as optic nerve head drusen or papilledema.
  4. Furthermore, as a side effect of some drugs or hazardous exposures, relative scotomas can occur. 

Recognising these prevalent reasons is critical for eye care practitioners because it allows them to conduct targeted examinations and interventions to address the underlying disorders and optimise visual function in patients.

Summary

Relative scotoma:

Definition and Characteristics: this condition causes a partial or relative loss of eyesight as well as a decrease in visual sensitivity.

Common underlying causes:  Refractive errors, retinal problems, optic nerve anomalies, drugs, or toxic exposures can all cause this.

Causes of scotoma

Optic nerve disorders

Explanation of the optic nerve's role

The optic nerve is a critical visual information canal, carrying impulses from the retina towards the brain. 

It is made up of nerve fibres and plays an important function in transferring visual stimuli to the brain, allowing it to interpret and understand images. 

Any disturbance in the optic nerve's normal functioning can have a direct influence on the quality and quantity of visual information entering the brain.10

Scotomas can be caused by optic nerve diseases, which impair visual perception. 

Optic neuritis, characterised by inflammation of the optic nerve, and ischemic optic neuropathy, caused by inadequate blood supply to the optic nerve, are two well-known causes. 

Additionally, scotomas can be caused by compressive injuries on the optic nerve, such as tumours, and disorders like glaucoma, which raise intraocular pressure.11

Retinal disorders

Explanation of the retina's role

The retina is an important component of the eye that converts light into neural impulses that the brain understands as vision. 

The retina, which is located in the back of the eye, contains specialised cells such as photoreceptors, which collect light and commence the visual process. 

The retina processes light information, which then travels via the optic nerve to allow for additional interpretation in the brain. 

The retina's integrity is critical for sustaining clear and correct vision.12

Disorders leading to scotoma

Various retinal conditions can cause scotomas by interfering with the regular functioning of this essential tissue. 

Macular degeneration, a condition in which the central region of the retina deteriorates, can result in central scotomas, which hinders detailed vision. 

Scotomas are also caused by diabetic retinopathy, a consequence of diabetes that affects the retinal blood vessels. 

Peripheral scotomas can be caused by retinal detachment, which is defined as the detachment of the retina from the tissue beneath it. 

Recognising these retinal abnormalities is critical for prompt treatment and visual health preservation.13,14

Migraines

Relationship between migraines and scotoma

Migraines, which are a form of headache disorder, can have an unusual association with scotomas. 

Individuals suffering from migraines may also experience visual problems known as migraine-associated scotomas in certain circumstances. 

These scotomas are generally linked with the headache phase of a migraine attack and manifest in the form of brief blind spots or zigzagging lines in the field of vision. 

The specific mechanisms underlying migraines and scotomas are unknown, however they may include alterations in blood flow to the brain's visual centres.15

Visual aura as a precursor

A visual aura, a characteristic feature before migraines, serves as a precursor to the migraine  and may consist of scotomas. 

Auras are brief visual disruptions that may include a sense of flashing lights, zigzag patterns, or momentary blind areas. 

Auras are thought to be caused by unusual electrical activity in the brain and serve as a warning indication of an impending headache16

Symptoms of scotoma17

Visual distortions

Description of distorted vision

Scotoma-related visual distortions manifest as changes in the ordinary way one perceives visual stimuli. 

This can involve incorrectly interpreting items' shapes, colours, or sizes within the region that is impacted. 

Distorted vision frequently makes it difficult to recognise and comprehend the visual environment, leading to an overall effect on visual perception.

Blind spots

Explanation of blind spots

With reference to scotomas, blind spots are localised sections of the field of view where vision is either severely decreased or completely missing. 

These areas operate as gaps in visual perception, posing difficulties in activities requiring entire visual awareness. 

Due in part to missing information in these precise places, people with blind spots may struggle with things like reading, driving, or manoeuvring congested spaces.

Flashes of light

Description of light flashes

Light flashes are quick and sudden bursts of lighting that people can see inside their visual field. 

In relation to scotomas, such flashes can be an indication of illnesses such as migraines or retinal problems. 

Light flashes are defined as perceiving short, shimmering lights or bursts which are not present in the surrounding environment. 

These visual abnormalities can be disturbing and indicate underlying problems with the eye or visual pathways.

Diagnosis of scotoma

Eye examinations

Importance of regular eye check-ups

Regular eye examinations are critical for early identification and surveillance of scotomas. 

Routine eye exams enable eye care experts to check the general well-being of the eyes, recognising any problems before they worsen. 

Given that scotomas can result from a variety of ocular and neurological diseases, regular eye exams are critical to preserving eye wellness and avoiding repercussions.

Techniques for detecting scotoma

Scotomas are detected during eye exams using specialised procedures.

A typical method is visual field testing, in which subjects react to visual stimuli shown in various parts of their field of view. Scotomas can be detected via abnormal reactions. 

Furthermore, optical coherence tomography (OCT) and fundus photographs offer detailed imaging of the retina, aiding in the diagnosis and characterisation of scotomas.18

Imaging tests

Role of imaging in identifying scotoma causes

Advanced imaging techniques are critical in determining the exact cause of scotomas. 

Magnetic resonance imaging (MRI) and computed tomography (CT) scans aid in the visualisation of the optic nerve, retina, and other important tissues. 

These tests are useful in diagnosing problems such as tumours, optic nerve disorders, or anomalies in the pathway of vision that can lead to the occurrence of scotomas.19

Treatment and management

Underlying condition treatment

Addressing optic nerve or retinal disorders

The therapy of underlying neurological or retinal diseases is critical in the management of scotomas. 

Treatments can involve surgery, laser treatment, or pharmaceutical treatments, depending on the issue. 

For example, resolving retinal detachment may necessitate surgical reattachment, but disorders such as glaucoma may necessitate intraocular pressure medicines. 

The goal of targeted treatment is to slow the evolution of the condition while minimising its effects on visual function.

Lifestyle changes

Suggestions for minimising scotoma impact

Individuals can adjust to the problems caused by scotomas by making lifestyle changes. 

Suggestions include improving lighting conditions for better vision, utilising magnifying aids for reading, and implementing ways to increase visual field awareness. 

Furthermore, leading a healthy lifestyle that includes regular physical activity and a well-balanced diet benefits general eye health. 

Individuals who are educated on practical tactics are better able to navigate daily activities despite the existence of scotomas.

Medications

Pharmaceutical options for managing symptoms

Medications are essential in controlling the symptoms of scotomas. 

Depending on the root cause, medical alternatives may include anti-inflammatory medicines, vasodilators, or intraocular pressure medications. 

Specific treatments addressing migraine manifestations, such as pain relievers or preventative medications, may be administered for persons developing scotomas as a result of migraines. 

Medication is chosen based on the individual's diagnosis, with the goal of alleviating symptoms and improving total visual function.

Prevention

Healthy lifestyle habits

Maintaining overall eye health

Adopting a healthy lifestyle is a proactive strategy to prevent the onset or advancement of illnesses that lead to scotomas. 

Wearing sunglasses to protect the eyes from extended exposure to ultraviolet (UV) rays, staying hydrated, and including eye-friendly components into your diet, such as those high in vitamins A, C, and E, all help to general eye health. 

Adequate relaxation and stress management are also essential elements of a healthy way of life that can improve ocular well-being and lower the risk of scotoma-related diseases.

Conclusion

Recap of scotoma

To summarise, scotoma is a multifaceted visual abnormality with central, peripheral, absolute, and relative manifestations. 

Central scotomas impact the centre of vision, whereas peripheral scotomas appear in the periphery. 

Absolute scotomas represent complete vision loss, and relative scotomas represent partial deficits. 

Symptoms include visual distortions, blind spots, and flashes of light.

Causes include optic nerve, retinal diseases, and migraines.

Eye exams and imaging tests are used to get a diagnosis. 

Treatment focuses on underlying issues, while lifestyle changes and drugs can help control symptoms. Healthy practices and regular eye exams are essential for prevention.

Emphasis on seeking professional help

Encouragement for those experiencing symptoms to consult healthcare professionals

Individuals experiencing symptoms such as visual abnormalities, blind patches, or flashes of light should seek expert assistance. 

Scotomas, because of their complexity, demand the knowledge of healthcare specialists such as ophthalmologists and neurologists for correct diagnosis and specific management. 

Early intervention is critical for preserving vision and preventing subsequent issues. 

FAQs

What is the main difference between the four kinds of scotoma?

The main difference is the extent of visual loss, central and peripheral scotomas affect specific locations, absolute scotomas represent complete loss, and relative scotomas represent partial loss.

References: 

  1. Spector RH. Visual fields. In: Walker HK, Hall WD, Hurst JW (eds.) Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd ed. Boston: Butterworths; 1990. http://www.ncbi.nlm.nih.gov/books/NBK220/  
  2. CHEUNG SH, LEGGE GE. Functional and cortical adaptations to central vision loss. Visual neuroscience. 2005;22(2): 187–201. https://doi.org/10.1017/S0952523805222071.
  3. Macular edema | National Eye Institute. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/macular-edema 
  4. Kumar S, El Menaisi AM. Stargardt’s disease presenting with bilateral central ring scotoma. Saudi Journal of Ophthalmology. 2018;32(4): 349–352. https://doi.org/10.1016/j.sjopt.2018.07.008
  5. Cho H k, Lee J, Lee M, Kee C. Initial central scotomas vs peripheral scotomas in normal-tension glaucoma: clinical characteristics and progression rates. Eye. 2014;28(3): 303–311. https://doi.org/10.1038/eye.2013.285.
  6. Types and causes of retinal detachment | national eye institute. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/retinal-detachment/types-and-causes-retinal-detachment
  7. Glaucoma. nhs.uk. https://www.nhs.uk/conditions/glaucoma/
  8. Hamel C. Retinitis pigmentosa. Orphanet Journal of Rare Diseases. 2006;1: 40. https://doi.org/10.1186/1750-1172-1-40.
  9. Refractive error - an overview | sciencedirect topics. https://www.sciencedirect.com/topics/medicine-and-dentistry/refractive-error
  10. Smith AM, Czyz CN. Neuroanatomy, cranial nerve 2(Optic). In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023. http://www.ncbi.nlm.nih.gov/books/NBK507907/  
  11. Hoorbakht H, Bagherkashi F. Optic neuritis, its differential diagnosis and management. The Open Ophthalmology Journal. 2012;6: 65–72. https://doi.org/10.2174/1874364101206010065
  12. Mahabadi N, Al Khalili Y. Neuroanatomy, retina. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2023. http://www.ncbi.nlm.nih.gov/books/NBK545310/ 
  13. Stahl A. The diagnosis and treatment of age-related macular degeneration. Deutsches Ärzteblatt International. 2020;117(29–30): 513–520. https://doi.org/10.3238/arztebl.2020.0513
  14. Nentwich MM, Ulbig MW. Diabetic retinopathy - ocular complications of diabetes mellitus. World Journal of Diabetes. 2015;6(3): 489–499. https://doi.org/10.4239/wjd.v6.i3.489
  15. Vincent M, Hadjikhani N. Migraine aura and related phenomena: beyond scotomata and scintillations. Cephalalgia : an international journal of headache. 2007;27(12): 1368–1377. https://doi.org/10.1111/j.1468-2982.2007.01388.x
  16. Viana M, Tronvik EA, Do TP, Zecca C, Hougaard A. Clinical features of visual migraine aura: a systematic review. The Journal of Headache and Pain. 2019;20(1): 64. https://doi.org/10.1186/s10194-019-1008-x 
  17. Scotoma - an overview | sciencedirect topics. https://www.sciencedirect.com/topics/neuroscience/scotoma 
  18. Handley SE, Šuštar M, Tekavčič Pompe M. What can visual electrophysiology tell about possible visual-field defects in paediatric patients. Eye. 2021;35(9): 2354–2373. https://doi.org/10.1038/s41433-021-01680-1
  19. Rao AA, Naheedy JH, Chen JYY, Robbins SL, Ramkumar HL. A clinical update and radiologic review of pediatric orbital and ocular tumors. Journal of Oncology. 2013;2013: 975908. https://doi.org/10.1155/2013/975908

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