What is Amblyopia or Lazy Eye?
by Dr. Jeffrey
Cooper & Rachel
Cooper (no relation). © 2001-2013
What is Amblyopia or Lazy Eye?
Amblyopia (Lazy Eye) and Strabismus are not the same condition.
What Causes Amblyopia or Lazy Eye?
Diagnosis of Amblyopia
Amblyopia Lazy Eye Treatments
is Amblyopia or Lazy Eye?
Amblyopia, commonly known as lazy eye, is the
eye condition noted by reduced vision not correctable
by glasses or contact lenses and is not due
to any eye disease. The brain, for some reason,
does not fully acknowledge the images seen by
the amblyopic eye. This almost always affects
only one eye but may manifest with reduction of
vision in both eyes. It is estimated that three
percent of children under six have some form of
Eye) and Strabismus are not the same condition.
Many people make the mistake of saying that a
person who has a crossed or turned eye (strabismus)
has a "lazy eye," but lazy eye (amblyopia) and
strabismus are not the same condition. Some of
the confusion may be due to the fact that strabismus
can cause amblyopia. Amblyopia can result from
a constant unilateral strabismus (i.e.,
either the right or left eye turns all of the
time in one direction). Alternating and/or intermittent strabismus
(an eye turn which turns in different directions and/or occurs only some of the time)
rarely causes amblyopia.
While a large eye turn or deviation (strabismus) is easily
spotted by the layman, amblyopia without strabismus
or associated with a small deviation is usually not noticed by parents or pediatricians.
Only an eye doctor expert in examining infants and young children can detect this type of amblyopia.
This is why early infant and pre-school eye examinations by an eye care professional
are so necessary. Eye exams by a pediatrician or school eye screenings are not a substitute for a comprehensive vision examination by a developmental optometrist or primary eye care doctor.
Due to misunderstanding or misuse of the terms
for different visual conditions (i.e., crossed
eyes vs. lazy eye), many people are inaccurately
labelled as having a "lazy eye." If you think
you or someone you know has lazy eye, it is recommended
that you learn more at What is a Lazy Eye? - Comprehensive Patient Education and What
is Strabismus?. In addition, there is a related visual condition which is common, not detected by
the standard 20/20 eye test, and can be mistaken for lazy eye - see What
is Convergence Insufficiency?
To complete the picture, find out about all amblyopia and strabismus treatment
What Causes Amblyopia or a Lazy Eye?
Both eyes must receive clear images
during the critical period. Anything that interferes
with clear vision in either eye during the critical
period (birth to 6 years of age) can result in
amblyopia (a reduction in vision not corrected
by glasses or elimination of an eye turn). The
most common causes of amblyopia are constant strabismus
(constant turn of one eye), anisometropia (different
vision/prescriptions in each eye), and/or blockage
of an eye due to trauma, lid droop, etc. If one
eye sees clearly and the other sees a blur, the
good eye and brain will inhibit (block, suppress,
ignore) the eye with the blur. Thus, amblyopia
is a neurologically active process. The inhibition
process (suppression) can result in a permanent
decrease in the vision in that eye that can not
be corrected with glasses, lenses, or lasik surgery.
Since amblyopia usually occurs in one eye only,
many parents and children may be unaware of the
condition. Far too many parents fail to take their
infants and toddlers in for an early comprehensive
vision examination and many children go undiagnosed
until they have their eyes examined at the eye
doctor's office at a later age.
The most important diagnostic tools are the special
visual acuity tests other than
the standard 20/20 letter charts currently used
by schools, pediatricians and eye doctors. Examination
with cycloplegic drops can be necessary to detect
this condition in the young.
Early treatment is usually simple, employing eyeglasses, drops, Vision Therapy, and/or eye patching. While detection and correction before the age of two
is considered to offer the best outcomes, recent scientific research has disproven the long held belief that children over a certain age (seven or whatever) can not be successfully treated. In fact, many scientific studies on neuroplasticity of the brain in adults are now showing that therapies can improve the vision in amblyopic or lazy eye conditions in older children AND adults. See information on recent scientific studies and research on amblyopia and lazy eye treatments.
Treatment of amblyopia after the age of 17 is not
dependent upon age but requires more effort including
therapy. Every amblyopic patient deserves an
attempt at treatment.
To quote one of our members, Dr. Leonard J. Press, FAAO, FCOVD: "It's been proven that a motivated adult with strabismus and/or amblyopia who works diligently at Vision Therapy can obtain meaningful improvement in visual function. As my patients are fond of saying: "I'm not looking for perfection; I'm looking for you to help me make it better". It's important that eye doctors don't make sweeping value judgments for patients. Rather than saying "nothing can be done", the proper advice would be: "You won't have as much improvement as you would have had at a younger age; but I'll refer you to a vision specialist who can help you if you're motivated."
In conclusion, improvements are possible at any age, but early detection and treatment offer the best outcome. If not detected and treated early in life, amblyopia can cause a permanent loss of vision with associated loss of stereopsis (two eyed depth perception). Better vision screenings are needed for young children. The 20/20 eye chart screening is not adequate.
Amblyopia causes more visual loss in the under 40 group than all
the injuries, and diseases combined in this age