Amblyopia translates as "blunt vision".
The weakness is not at the level of the person's eye, the blunt vision is due to the brain's suppression of the input from the eye.
It is sometimes incorrectly called 'Lazy Eye' but there is no laziness going on here! It takes more effort to suppress the input than it would to use it in a binocularly / spatially efficient manner.
The suppression is typically due to the infant having abnormal visual experiences during a sensitive period of development (usually around 18 months of age) which disrupts neuronal circuitry in the visual cortex of the brain and results in abnormal spatial vision and reduced visual acuity. The trigger factors can be illness, fevers, injury or stress ( visual stress, emotional stress). Genetics plays a significant role as well. Once the stress event has disrupted the Vision that was probably destined to be normal binocularity, the vision starts to be more "one-eyed" and so the suppression occurs, and there are usually significant consequences thereafter.
Once the stress event has disrupted the Vision that was probably destined to be normal binocularity, the vision starts to be more "one-eyed" and so the suppression occurs, and there are usually significant consequences thereafter.
The suppression is usually limited to just a tight central zone of the Field of Vision, the person still enjoys good peripheral vision with the Amblyopic eye.
The consequence of the suppression can be that the suppressed eye is less likely to stay straight, and the development of normal focus is disrupted; resulting in an eye that may be either not straight or very blurry compared to the other eye, or both.
There is a cost to this suppression, it is a strictly 'one-eyed' phenomenon, it is a 'two-eyed' adaption and both eyes pay a price for the suppression that occurs at the level of the brain.
Indeed for some people both eyes are suppressed as the brain’s stress-response, resulting in poorer vision for both eyes. this is called Streff's Syndrome, named after an American optometrists, John Streff.
(Some practitioners believe that the eye turns first and/or the blur occurs first, then followed lastly by the development of suppression as a response to the diplopia or fuzzy focus.)
Once established, the suppression can be hard to lift. The subconscious brain has chosen to suppress one eye's central input for its own reasons and it is not easy to persuade the subconscious brain to revise its management of the visual input. The longer the suppression goes untreated the more difficult it can be to lift.
There is no age at which improvement may be ruled out, it depends on how deeply the brain is suppressing the visual imput not the patients age.
Visual acuity and stereopsis can often be improved with Optometric Vision Therapy which strives to re-awaken the value of the central acuity and the value of enhanced stereopsis.
Book an appointment with Mark Eagle to investigate this further.