Definition

Scotoma refers to a blind spot in the visual field that impairs vision. This condition can affect one or both eyes and may occur in the center or at the periphery of the visual field.

Scotoma can be either temporary or permanent. Temporary scotomas might indicate the onset of a migraine headache or signify a more serious health issue that could lead to blindness.

There are three types of scotoma:

1. Central Scotoma

Central scotoma manifests as a blind spot in the middle of one's vision, impacting the ability to see, read, and perform daily tasks.

2. Scintillating Scotoma

Individuals with scintillating scotomas may experience blurred vision and see floating objects or dots (floaters) within their visual field.

3. Paracentral Scotoma

In paracentral scotoma, the blind spot appears around the central vision area but not directly in it. When accompanied by peripheral vision loss, this condition can lead to tunnel vision.

Causes

There are various factors or medical conditions that can cause scotoma, depending on the type:

1. Central Scotoma

• Macular Degeneration: Age-related macular degeneration (AMD) is the most common cause of central scotoma, affecting the macula (small part of the retina), which is crucial for central vision.
• Diabetic Retinopathy: High blood sugar levels in diabetes can damage the retina, leading to vision problems.
• Optic Neuropathy: Reduced or disrupted blood flow to the optic nerve can cause sudden vision loss.

2. Scintillating Scotoma

• Medications: Certain drugs, such as digoxin used for chronic heart failure or antiarrhythmic agents, can cause vision changes due to toxicity affecting the photoreceptors.
• Sclerotherapy: A medical procedure used to treat varicose veins.

3. Paracentral Scotoma

• Glaucoma: This eye disorder damages the optic nerve.
• Diabetic Retinopathy: As with central scotoma, high blood sugar levels in diabetes can damage the retina.

Risk Factor

Several risk factors for developing scotoma include:

• Diabetes
• Glaucoma
• High blood pressure
• Cardiovascular disease
• Stroke
• Multiple sclerosis
• History of migraines
• Excessive stress and anxiety

Symptoms

Symptoms of scotoma vary according to the type but generally include:

• (Temporary or permanent) vision loss or blindness 
• Decreased visual acuity
• Presence of one or several blind spots in the visual field
• Headaches
• Black dots or floaters in the visual field
• Difficulty in reading or distinguishing detailed or specific colors

Diagnosis

To diagnose scotoma, a doctor will conduct a thorough medical interview, physical examination, and additional diagnostic tests if needed.

During the medical interview, the doctor will inquire about the symptoms, their onset, and the patient's medical history. The physical examination will focus on the eyes, with particular tests including:

• Visual Field Test: This test uses specialized equipment to evaluate the patient's visual field.
• Pupil Dilation: Eye drops are used to dilate the pupils, allowing the doctor to examine the retina and optic nerve more thoroughly.

These examinations help the doctor determine the type of scotoma and its underlying cause.

Management

The treatment for scotoma depends on its underlying causes. A detailed medical history and symptom assessment will guide the doctor in determining the appropriate therapeutic steps. It is important to note that scotoma may not completely resolve even with therapy.

Adapting to visual field loss by optimizing the remaining vision can be beneficial. Here are some tips to help improve vision:

• Use more and better lighting.
• Utilize high-contrast materials.
• Enlarge reading text with tools like magnifying glasses.
• Switch to devices with audio capabilities, such as voice-activated smartphones, text-to-speech software, talking watches, and audiobooks.

Learning to use the peripheral visual field, known as eccentric viewing, can also be helpful. This technique involves looking slightly away from the object to utilize the outer visual field rather than the central visual field.

By employing peripheral vision, one relies on rod cells instead of the damaged cone cells located in the macula. Although cone cells are responsible for sharp and colored vision, rod cells can be trained to assist in their function.

The eyes and brain can adapt to new techniques and ways of seeing through:

• Proper exercise
• Consistent practice
• Appropriate visual aids

Living with a scotoma can be visually disruptive, but learning to adapt by making the most of your remaining vision can make a difference to your independence and ability to carry out activities.

Complications

Scotoma is not inherently dangerous, but it can significantly impact the quality of life.

Prevention

There is no specific method to prevent central scotoma, but maintaining eye health can reduce the risk. Here are some preventive measures:

• Healthy diet: Consume plenty of green vegetables like spinach, cabbage, and mustard greens. Consumption of fish high in omega-3 fatty acids, such as salmon, tuna, and halibut, are also beneficial for eye health.
• Regular exercise: Physical activity helps maintain overall health and reduces the risk of conditions that can cause eye problems, such as diabetes, high blood pressure, and high cholesterol.
• Quit smoking: Smoking increases the risk of macular degeneration, cataracts, and optic nerve damage.

You also need to protect your eyes from things that can injure them:

• Sunglasses: Wear sunglasses that block 99 to 100 percent of UVA and UVB radiation to protect your eyes from the sun.
• Goggles: Use goggles during activities like sports, construction, or home repairs to protect your eyes from injury.
• Resting eyes: Take breaks every 20 minutes when using a computer to prevent eye strain.
• For contact lens users, preventing eye infections involves washing hands before handling lenses, disinfecting lenses properly, and replacing them regularly.

When to See a Doctor?

Consult an ophthalmologist if you suddenly experience scotoma or other vision problems. Immediate medical attention is required for emergency conditions, such as:

• Confusion or disorientation
• Dizziness or vomiting
• Muscle weakness
• Sudden severe headache
• Scotoma symptoms following a head or eye injury

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