Amblyopia, otherwise known as lazy eye, is a disorder of the visual system that is characterized by poor or indistinct vision in an eye that is otherwise physically normal, or out of proportion to associated structural abnormalities. It has been estimated to affect 1–5% of the population.
The problem is caused by either no transmission or poor transmission of the visual stimulation through the optic nerve to the brain for a sustained period of dysfunction or during early childhood thus resulting in poor or dim vision.
Amblyopia normally only affects one eye, but it is possible to be amblyopic in both eyes if both are similarly deprived of a good, clear visual image. Detecting the condition in early childhood increases the chance of successful treatment.
While the colloquialism "lazy eye" is frequently used to refer to amblyopia, the term is inaccurate because there is no "laziness" of either the eye or the amblyope involved in the condition. "Lazy brain" is a more accurate term to describe amblyopia. The term "lazy eye" is imprecise because it is also a layman's term for strabismus, particularly exotropia.
Amblyopia is a developmental problem in the brain, not an
organic problem in the eye (although organic problems can induce
amblyopia which persist after the organic problem has resolved).
The part of the brain corresponding to the visual system
from the affected eye is not stimulated properly, and develops
abnormally.
This has been confirmed via direct brain examination.
David H. Hubel and Torsten Wiesel won the Nobel Prize in Physiology or
Medicine in 1981 for their work demonstrating the irreversible damage to
ocular dominance columns produced in kittens by sufficient visual
deprivation during the so-called "critical period".
The maximum critical period in humans is from birth to two years old.
Further Reading
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"Amblyopia"
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