Loss of VA in one or both eyes that cannot be improved by corrective lenses
Amblyopia
Amblyopia and pathology
Pathology is absent
What is the most common cause of monocular visual impairment in children and middle-aged adults?
Amblyopia
What happens it amblyopia is not treated?
Persists throughout life
Take home points of treating amblyopia
- critical period
- patient compliance
- effects choices as an adult
What is decreased VA caused by?
- pattern vision deprivation, and/or
- abnormal binocular interaction
No ________ or _________ (that can be treated or reversed) can be detected by physical examination of the eye
- causes
- etiology
For amblyopia, be suspicious if there is a loss of ____________ lines of VA that is not causes by pathology or correctable by ordinary refractive correction.
At least two lines
In addition to the loss of VA, amblyopia can result in
- dysfunction in accommodation
- poor eye alignment (constant strabismus)
- reduced contrast sensitivity
- dysfunction in spatial judgment
- resolution is poor
- mono fixation could develop
What percentage of US population has amblyopia?
2-4%
Degrees of amblyopia
Can be unilateral, bilateral, can be mild to severe
Critical period of amblyopia (age)
Between 8-10 yo
-has to be detected before this time, or it can be irreversible. This shows the importance of early detection
Critical period
- visual system still developing
- neurological sensory development of the visual system is NOT impaired
- not completely sure exactly how long period is
- not sure what treatments are needed after the critical period
What helps with the development of the visual system and visual potential in the critical period
Stimulation
-treatment will be better during this period
Abnormal input after a normal critical period
Results in blur but not a halt to the sensory development of the visual potential
Abnormal or lack of input during critical period
Results in a blurred image
Differences in critical periods
Could be different for different amblyogenic factors
E.g. Anisometropia vs isometropia
Some refractive errors in young infants
There is a need for emmetropization, where treating early could upset the natural change needed in these infants, but treating too late could also lead to amblyopia
Why does amblyopia (functional amblyopia) occur?
Because the visual pathway failed to develop properly due to inadequate stimulation, which could cause dissimilar images and binocular dysfunction
Most common causes for amblyopoia
strabismus and anisometropia
Can a phoria cause amblyopia?
NO! Both eyes are working together
Refractive ablyogenic conditions
Cause blur
- anisometropia
- isoametropia
- meridonial
Strabismus conditions of amblyopia
Caused by different targets
- esotropia
- exotropia
- hypertropia
Deprivation as an amblyogenic condition
Caused by degraded image or occlusion
- cataract
- ptosis
