Refractive amblyopia is a type of “lazy eye” that is due to the eye having a high amount of error in the focusing system. This condition is most common in children and does not develop after childhood but will be a lifelong condition.
Basics of Amblyopia
Amblyopia is the term for a “lazy eye” or an eye that cannot see as well as it should, despite not having any other disease.
Since the definition of amblyopia requires an eye to not have reduced vision from a medical condition, things such as glaucoma, macular degeneration, or retinal detachments will never result in amblyopia even if they cause blurred vision.
There are multiple types of amblyopia including occlusion amblyopia, strabismus amblyopia, and refractive amblyopia.
The types of amblyopia are determined based on the associated factors contributing to the reduced vision.
In occlusion amblyopia, there is a true blockage depriving the eye of the ability to see and develop normally.
In strabismus amblyopia, there is an eye turn which causes the eye to not develop properly and have reduced vision.
In refractive amblyopia, there is a large amount of error or difference in the focusing system of the eyes.
Types of Refractive Error
Refractive error is a general term used for any focusing system problems which require glasses or contact lenses.
Nearsightedness, farsightedness, and astigmatism are the most common types of refractive errors and are responsible for refractive amblyopia.
In most cases, any of these refractive errors can be corrected with glasses or contact lenses and the individual can still see 20/20 when wearing glasses or contacts.
Reduced Vision with Glasses
If glasses or contact lenses are unable to correct the individual to 20/20 due to a high amount of refractive error, then refractive amblyopia may be present.
Refractive amblyopia may occur with nearsightedness, farsightedness, or astigmatism.
Many times, before the diagnosis of refractive amblyopia is made, there will be additional testing done to rule out other possible causes of the blurred vision.
Causes of Refractive Amblyopia
While any of the three types of refractive errors may result in amblyopia, each has a different amount at which refractive amblyopia may occur.
For nearsightedness, if there is a difference of 3 diopters between the two eyes, the more nearsighted eye may develop refractive amblyopia. Also, if both eyes have more than 8 diopters of nearsightedness, both eyes are at risk of developing refractive amblyopia.
For farsightedness, if there is a difference of 1 diopter between the two eyes, the more farsighted eye may develop refractive amblyopia. If both eyes have 5 or more diopters of farsightedness, then both eyes are at risk of amblyopia.
For astigmatism, if there is a difference of 1.5 diopters, or both eyes have 2.5 diopters of astigmatism, the eye may develop refractive amblyopia.
Treating Refractive Amblyopia
To treat refractive amblyopia, glasses or contact lenses are needed to correct both eyes to the best possible correction.
If there is still residual blurry vision, active treatment such as vision therapy or patching of an eye may be indicated as a way to build equal vision between the eyes.