nyctalopia

/,niktə'loupiə/
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nyctalopia

A person with nyctalopia struggles to read a book in a dimly lit room.

Definition
  1. Noun:
    • A medical condition characterized by poor vision in dim light or at night: Nyctalopia is the inability to see clearly in low-light conditions, such as at dusk or in a darkened room. It is often caused by a deficiency of vitamin A or by certain disorders of the retina.
Usage Examples
  • Noun:
    • The doctor diagnosed the patient's difficulty driving at night as nyctalopia.
    • A diet lacking in vitamin A can lead to nyctalopia.
    • His nyctalopia made it challenging to navigate the poorly lit path after sunset.
Advanced Usage
  • Medical Context: The term is primarily used in clinical and ophthalmological settings to describe a specific symptom or condition.
    • The study focused on the genetic factors contributing to congenital nyctalopia.
Variants and Related Words
  • Night Blindness: This is the common, non-technical term for nyctalopia.
    • Many people refer to nyctalopia simply as "night blindness."
  • Hemeralopia: This is a related but distinct condition meaning day blindness (poor vision in bright light), which is sometimes confused with nyctalopia.
Synonyms
  • Night Blindness: The most direct and common synonym.
  • Moon Blink: An archaic or poetic term rarely used in modern English.
Antonyms
  • Photopia: The normal vision of the eye in bright light, mediated by the cone cells. (Note: This is a technical term for the opposite visual state, not a direct antonym for the of nyctalopia).
  • Normal night vision: The absence of the condition.
Notes on Meaning
  • Primary Meaning: The core meaning is impaired vision in low light. It is a symptom, not a disease itself.
  • Common Cause: While retinal disorders can cause it, nyctalopia is most famously associated with vitamin A deficiency, which is a major cause of preventable blindness in some parts of the world.
  • Distinction from Hemeralopia: It is crucial to distinguish nyctalopia (night blindness) from hemeralopia (day blindness), as they are opposite conditions. Confusion between these terms exists even in some historical texts.
nyctalopia

A person with nyctalopia struggles to read a book in a dimly lit room.

Noun
  1. inability to see clearly in dim light; due to a deficiency of vitamin A or to a retinal disorder

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