The brain and the eyes work together to provide us with the most valuable thing of all time i.e. ‘vision’. Human eye focuses light rays onto the back portion of the eye known as the retina. Cells of this retina subsequently trigger nerve signals which travel along the optic nerves to the brain. Amblyopia is the medical term used when the vision of a single eye is diminished since it fails to operate properly together with the brain. The eye itself looks normal, but for several reasons, the mind favors another eye. This problem is also referred as a lazy eye.
What Causes Amblyopia?
Amblyopia may result from any condition that prevents the eye from clearly focusing at objects or surroundings. Amblyopia can also be originated by the misalignment of the two eyes–a condition known as strabismus. With strabismus, the eyes can cross (esotropia) or flip out (exotropia). At times, amblyopia results from a clouding of the front area of the eye, a condition referred to as a cataract.
A common cause of amblyopia is that the inability of a single eye to concentrate as well as the other one. Amblyopia may occur when a single eye is more nearsighted, more farsighted, or has more astigmatism. These terms refer to the ability of the eye to focus light on the retina.
Farsightedness, or hyperopia, occurs when the distance from front to the rear of the eye is too short. Eyes which are farsighted are inclined to focus better in a distance but have more trouble focusing on nearby objects.
Nearsightedness, or myopia, occurs when the eye is too long from front to back. Eyes with nearsightedness have a tendency to focus better on nearby objects. Eyes with astigmatism have trouble focusing on far and near objects due to their irregular shape.
Depending on the underlying causes there are 3 types of amblyopia, :
Strabismic amblyopia. Strabismus is the most frequent cause of amblyopia. To prevent double vision caused by poorly aligned eyes, the brain ignores the observable input from the misaligned eye, resulting in amblyopia because of the eye (that the “lazy eye”). This kind of amblyopia is called strabismic amblyopia.
Refractive amblyopia. At times, amblyopia is caused by unequal refractive errors in the eyes, despite perfect eye alignment. For example, a single eye may have evident uncorrected nearsightedness or farsightedness, whereas the other eye does not. Or one eye could have significant astigmatism along with the other eye doesn’t.
In such instances, the brain relies on the eye which has significantly less uncorrected refractive error and “tunes out” the blurry vision from another eye, causing amblyopia in that eye from disuse. This specific type of amblyopia is known as refractive amblyopia (or anisometropic amblyopia).
Deprivation amblyopia. This type of lazy eye condition is caused due to something which obstructs light from entering and being concentrated at a baby’s attention, such as a congenital cataract. Immediate treatment of congenital cataracts is imperative to permit normal visual development to occur.
As described by the College of Optometrists in Vision Development, Treatment for amblyopia includes:
Proper eyeglasses or contact lenses can help reduce pressure so that the under-used eye can begin to work more efficiently.
Vision therapy to equalize vision in both eyes, improve eye coordination and re-establish clear single vision.
Forcing the weaker eye to operate by blocking or fogging the favored eye with specific lenses, an eye patch or eye drops.