scotoma

/skɔ'toumə/

Thân thiện

A patient points to a scotoma on a visual field chart.

Definition

1. Noun:
   • An isolated area of diminished vision within the visual field: A scotoma is a blind spot or area of reduced vision in an otherwise normal visual field. It is not a complete loss of vision but a localized defect.

Usage

• A scotoma is a medical term used primarily in ophthalmology and neurology to describe a specific visual deficit.
• It is often a symptom of an underlying condition affecting the visual pathway, such as migraine, glaucoma, or damage to the retina or optic nerve.
• The word is typically used in singular form but can be pluralized as or .

Examples

• Noun:
  • The patient reported a central scotoma, making it difficult to read.
  • Migraine auras can sometimes manifest as a scintillating scotoma, a shimmering blind spot.
  • The ophthalmologist mapped the scotoma using a visual field test.

Advanced Usage

• "Central scotoma": A blind spot affecting the central, high-acuity part of the visual field, often associated with macular degeneration.
• "Peripheral scotoma": A blind spot in the outer edges of the visual field.
• "Scintillating scotoma": A temporary area of visual disturbance that often shimmers or flickers, commonly associated with migraine aura.
• "Physiological blind spot": The normal scotoma in each eye corresponding to the optic disc, where there are no photoreceptor cells.

Variants and Related Words

• Scotopic (adj): Relating to or denoting vision in dim light, mediated by rod cells in the retina. (Note: This is related through the Greek root meaning 'darkness' but describes a different concept).
• Hemianopia (n): Loss of vision in half of the visual field, which can be considered a very large scotoma.

Synonyms

• Blind spot: A more general, non-technical term for an area where vision is absent or impaired.
• Visual field defect: A broader term encompassing scotomas and other patterns of vision loss.

Antonyms

• Full visual field: A complete, unimpaired field of vision.
• Normal vision: Vision without any areas of diminishment.

Notes

• A scotoma is subjective; the person experiencing it is aware of a gap or blur, but the brain often attempts to "fill in" the missing information from the surrounding visual field.
• The term originates from the Greek , derived from (darkness).

Học thuật

Noun

1. an isolated area of diminished vision within the visual field