What is a Scotoma? - Definition, Types & Causes

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  • 0:04 Injuries & Visual Problems
  • 0:43 What Is a Scotoma?
  • 1:11 Types of Scotoma
  • 2:40 Causes of Scotoma
  • 4:14 Lesson Summary
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Lesson Transcript
Instructor: Patricia Jankowski

Patricia has a BSChE. She's an experienced registered nurse who has worked in various acute care areas as well as in legal nurse consulting.

A scotoma is an interruption or break in the visual field, surrounded by a remaining normal visual field. This lesson is about scotoma and the types and causes of this visual disorder.

Injuries & Visual Problems

''Dictation: This is Dr. Tim Rogers, dictating on John Doe, June 29, 2017. Mr. Doe is a pleasant, physically fit 28-year-old Caucasian male who sustained a coup contrecoup brain injury in a skydiving accident. His parachute opened too early, and he was thrown around quite a bit by the gravitational force of the sudden line snapping. He was unconscious for a brief period of time, probably less than thirty minutes. His friends called 9-1-1, and he was brought to the ER in an ambulance. He woke up in the ER and was oriented to person, place and time, but his first verbal comment was, Doc, I can't see right!''

What Is a Scotoma?

A scotoma is a break or interruption in the visual field. The plural of the word is not scotomas, as one might think, but is scotomata. A scotoma can occur in one eye or both, in the center or at the outer edges of the visual field, and can occur alone or there can be several. It can be temporary, but in the majority of cases, it's permanent. There are many possible causes of scotoma, and it can be a very debilitating and life-altering disorder.

Types of Scotoma

There are several main types of scotoma. Most are permanent, but the type that's associated with a migraine headache is temporary and is often part of the headache aura, or subtle change in perception that occurs before the migraine begins.

Let's look at a few different types. A scintillating scotoma is the type of scotoma that occurs before the onset of a migraine headache. However, it can occur on its own. This scotoma appears as a flickering, arc-shaped light that encroaches upon the central visual field.

A central scotoma is perhaps the most troublesome type, as it's a dark spot in the center of the field of vision. The remaining visual field remains normal, often causing the patient to focus on the periphery, or outer boundaries, of the field. This makes daily activities such as reading and driving very difficult.

A peripheral scotoma is a dark spot along the edges of the field of vision. While it does interfere with normal vision and all activities that depend upon that, it's not as difficult to deal with as a central scotoma.

In a hemianopic scotoma, half of the visual field is affected by the dark spot. This can occur on either side of the center, and can affect one or both eyes, but usually affects them both. This is also sometimes called homonymous hemianopsia.

A paracentral scotoma is a dark spot that occurs near, but not in, the central visual field.

Lastly, there is the bilateral scotoma, which appears in both eyes and is caused by some type of brain tumor or growth. It is relatively rare.

Causes of Scotoma

A scotoma is actually not a disease unto itself, but is a symptom of some other underlying disease or cause. It's important to diagnose and treat the problem that caused the scotoma to prevent it from getting worse.

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