On this page
What Are Scotomas?
In medical terminology, the term “scotoma” refers to an area of partial or complete blindness within the visual field. This phenomenon is generally attributable to a wide range of underlying conditions, including various eye diseases, damage to nervous tissue, or unwanted side effects related to certain medications, such as the antibiotic streptomycin.
Scotomas can appear in several different forms, including dark spots, colored patches, or flashes of light, a phenomenon known as scintillating scotomas. They may affect one eye or both eyes simultaneously, and can significantly interfere with normal vision, sometimes making everyday tasks such as reading or driving considerably more difficult.
The appropriate treatment for scotomas varies considerably depending on the specific underlying condition responsible for their appearance. In many cases, the sudden onset of a scotoma is indicative of an already developing underlying disease process. For this reason, it is important to seek prompt medical evaluation as soon as this symptom is noticed, rather than waiting to see if it resolves on its own.
Basics of Eye Physiology
Three main anatomical components work together to ensure proper visual function:
Cornea and Lens: These structures are positioned at the front portion of the eyeball and are responsible for focusing incoming light from the external environment, allowing images to be properly projected onto the retina at the back of the eye.
Retina: This is composed of specialized tissue that is sensitive to both light and color, located at the back of the eye. The retina’s primary function is to convert visual stimuli into electrical signals, which can then be transmitted along the nervous system to the brain. The central portion of the retina is known as the macula, and it represents the most critical area for sharp, detailed central vision.
Optic Nerve: This nerve transmits the electrical signals generated by the retina directly to the brain, where they are interpreted, allowing us to consciously perceive and understand the information about light, color, and shape that has been received by the eye.
What Causes Scotomas?
Scotomas can be caused by a wide variety of different underlying conditions, including:
- Diseases affecting the macula
- Retinal detachment
- Diabetic retinopathy
- Retinoblastoma
- Disorders affecting the optic nerve, including glaucoma, optic neuropathies, and optic neuritis
- Lesions affecting the visual pathways, extending anywhere from the retina to the visual processing centers within the brain’s cortex
- Vascular problems, including retinal artery spasm and retinal hemorrhage
- Migraine
- The use of certain medications, such as streptomycin
- Nuclear cataract (central clouding of the eye’s natural lens)
In pregnant women, the sudden appearance of scotomas can serve as a warning sign of severe preeclampsia, a dangerous form of pregnancy-induced high blood pressure that requires urgent medical attention.
Classification of Scotomas
Scotomas appear within the visual field whenever the retina experiences a localized loss of sensitivity, and they can generally be classified into two main types:
-
Negative Scotomas: These present as dark or black spots that either completely prevent clear vision within the affected area, or allow only partial, degraded vision.
-
Positive Scotomas: These appear as areas of variable color, or as regions within the visual field characterized by intermittent flashes of brightness or light.
Depending on the specific underlying condition responsible, scotomas can be further classified as follows:
-
Physiological Scotoma (also known as the blind spot, or Mariotte’s blind spot): This corresponds to a naturally occurring, normal area of absent vision located at the point where the optic nerve exits the eye. Every person has this blind spot, but the brain normally compensates for it so effectively that it typically goes unnoticed in everyday life.
-
Central Scotoma: This affects the central portion of the visual field, precisely the area used for direct, focused vision when looking at objects. It can occur with age-related macular degeneration (AMD), infectious conditions such as toxoplasmosis, areas of chorioretinitis, or disturbances affecting nerve conduction, such as various optic neuropathies.
-
Paracentral Scotoma: This affects the paracentral area, meaning the region surrounding the macula, which can experience partial or complete reduction in light sensitivity. This type typically occurs in conditions affecting the macula or optic nerve.
-
Peripheral Scotoma: This is generally associated with retinal diseases or chorioretinal disorders affecting the outer regions of the visual field.
-
Centrocecal Scotoma: This type begins as a small area of vision loss but gradually expands over time, eventually involving both the macula and the physiological blind spot. It typically occurs in optic nerve diseases and certain metabolic storage disorders.
-
Annular (Ring) Scotoma: This is generally caused by retinitis pigmentosa and presents as a circular, ring-shaped blind area within the visual field.
-
Arcuate Scotoma: This corresponds to an arc-shaped blind area within the visual field, typically caused by damage to the optic nerve, and is a finding classically associated with glaucoma.
-
Scintillating Scotoma: This presents in front of the eyes as a dark spot that causes the perception of colored or shimmering, sparkling lines or patterns, and is typically associated with migraine, particularly migraine with aura.
How Do Scotomas Present?
Depending on the specific case, scotomas can cause the perception of:
- Dark spots
- Colored patches
- Flashing or sparkling lights
Any of these visual disturbances can significantly interfere with normal vision and daily activities.
Typically, these visual symptoms occur without any other accompanying physical complaints, which means that in certain conditions, such as glaucoma, a person may only become aware of the problem once significant, advanced narrowing of the visual field has already occurred, since the gradual, painless nature of the vision loss often goes unnoticed in its earlier stages.
In order to limit the potential for permanent vision damage, it is important to consult a doctor as soon as this disturbance first appears, rather than waiting for symptoms to worsen.
Scintillating Scotomas
Scintillating scotomas are a classic manifestation of aura, a specific set of sensory symptoms that, in some patients, precede the onset of a migraine headache.
These can present in a variety of ways, but typically manifest as shimmering trails or streaks of light that interfere with normal vision. They generally affect both eyes simultaneously and, unlike negative scotomas, the affected area is not perceived as dark, but rather as an area of bright, shimmering, or colorful visual disturbance.
When to See a Doctor
It is strongly recommended to promptly report the perception of any scotoma to a doctor, since this symptom is often the manifestation of progressive damage caused by an underlying disease at a more or less advanced stage, one that could potentially benefit significantly from the earliest possible diagnosis and intervention.
An important exception to this rule involves scintillating scotomas specifically related to migraine with aura. Once these have been recognized and diagnosed with certainty by a healthcare provider, they are generally not associated with any further specific complications, aside from the obvious temporary impact on vision during the episode itself, which could potentially pose risks in situations such as driving or operating dangerous machinery while symptoms are actively present.
Diagnosis
The presence of a scotoma is generally confirmed during a comprehensive eye examination, which typically includes a formal visual field test. During this test, the patient rests their chin and forehead against a specialized instrument that presents a series of visual stimuli, allowing precise measurement and mapping of vision throughout the entire space surrounding the point of fixation.
Following this initial examination, additional diagnostic testing may be recommended, including:
-
Optical Coherence Tomography (OCT) of the Optic Disc and Macula: This is a non-invasive imaging test that provides extremely high-resolution images of the eye’s internal structures. It offers detailed information about structural changes within the retina, allowing precise identification of the exact location and extent of any abnormality.
-
Neurological Evaluation: A comprehensive neurological assessment may be recommended, particularly when the scotoma is suspected to originate from a problem affecting the visual pathways within the brain, rather than from the eye itself.
Treatment and Remedies
The appropriate treatment for scotomas is directly tied to addressing the specific underlying condition responsible for their development. Treatment approaches vary considerably depending on the diagnosis:
-
Glaucoma: In cases of glaucoma, the use of eye drops designed to lower intraocular pressure is generally appropriate, as this helps prevent further progressive damage to the optic nerve, which is the underlying cause of vision loss in this condition.
-
Cataracts and Lens Disorders: When the underlying cause of a scotoma is attributable to a disorder of the eye’s natural lens, such as cataract, surgical intervention to implant an artificial intraocular lens may be indicated, and is generally highly effective at restoring clear vision.
-
Retinal Vascular Disease: Anticoagulant, antiplatelet, and thrombolytic medications may be used, under careful medical guidance, in cases involving retinal vascular disorders, such as arterial or venous vascular occlusions. Laser therapy may also be employed to address specific complications arising from these vascular conditions.
-
Migraine: In cases where scotomas are related to migraine, several treatment options may be considered depending on individual circumstances, including nonsteroidal anti-inflammatory drugs (NSAIDs) primarily to manage associated pain, ergotamine and triptan medications (particularly useful in cases of ophthalmic migraine attributable to blood vessel dilation), beta-blockers and calcium channel blockers (to help promote relaxation of blood vessels within the brain), and antidepressant or anticonvulsant medications used preventively to reduce the frequency of future migraine episodes.
Retinal Diseases: In retinal conditions such as age-related macular degeneration (AMD), it is essential to first determine the specific form of the disease present, whether dry (atrophic) or wet (exudative), in order to develop an appropriate treatment plan. Treatment approaches can vary significantly between these two forms, potentially including intravitreal injections and photodynamic therapy for the wet, exudative form, or the use of nutritional supplements containing lutein, zeaxanthin, omega-3 polyunsaturated fatty acids, and various vitamins to help support retinal health and slow progression in the dry, atrophic form.
- Retinal Detachment: In cases of retinal detachment, surgical intervention represents the primary treatment approach, with the goal of carefully repositioning the detached retina back into its correct anatomical location in order to restore and preserve vision.
Frequently Asked Questions
Are scotomas always a sign of a serious problem?
Not necessarily. While many scotomas are indeed related to significant underlying eye or neurological conditions that require prompt evaluation, scintillating scotomas associated with migraine with aura are generally benign once properly diagnosed, though they should still be evaluated by a doctor upon first occurrence to rule out other causes.
Can a scotoma go away on its own?
This depends entirely on the underlying cause. Scintillating scotomas related to migraine aura typically resolve on their own within 20 to 60 minutes as the aura phase passes. However, scotomas related to structural eye diseases, such as macular degeneration or retinal detachment, will not resolve without appropriate medical or surgical treatment addressing the underlying condition.
Is a scotoma the same as a floater?
No, these are different phenomena. Floaters are small, moving spots or shapes caused by tiny clumps of material within the vitreous gel of the eye, and they move with eye movement. A scotoma is a fixed area of reduced or absent vision within a specific portion of the visual field, and does not move as the eye moves.
Can stress cause scotomas?
While stress itself does not directly cause structural scotomas, it is a well-recognized trigger for migraine attacks in susceptible individuals, and can therefore indirectly contribute to the occurrence of scintillating scotomas associated with migraine aura.
Should I go to the emergency room if I suddenly see a blind spot?
If you experience the sudden onset of a new scotoma, particularly if it is accompanied by other symptoms such as sudden severe headache, weakness, difficulty speaking, or other neurological symptoms, you should seek emergency medical evaluation immediately, as this combination of symptoms could indicate a serious condition such as stroke or retinal detachment, both of which require urgent treatment.
Sources and Bibliography
- Bemme S, Pleyer U, Salehi N, Naxer S, Callizo J, Hoerauf H, Feltgen N. “Progressive Scotoma with Perception of Photopsia”, Ophthalmologe, January 2016;113(1):66-70
- Jin SW, Seo HR, Rho SS, Rho SH. “The Effects of Nocturnal Dip and Blood Pressure Variability on Paracentral Scotoma in Early Open-Angle Glaucoma”, Seminars in Ophthalmology, 2017;32(4):504-510
- American Academy of Ophthalmology: Understanding Vision Loss and Blind Spots
- National Eye Institute (NEI): Age-Related Macular Degeneration
