Amblyopia occurs when vision in one or both eyes does not develop properly during childhood.
It presents in 3%-5% of children and is usually unilateral; the extent of damage depends on severity, age of onset, and length of time before treatment. The affected eye triggers an abnormal brain response in development. The brain ignores the bad eye and with time this further erodes the visual acuity of the bad eye. You could call this a "Catch-22".
by Emily Groenendaal, MD, and
Amblyopia is an asymmetric visual acuity secondary to a disturbance of normal visual development. It presents in 3%-5% of children and is usually unilateral; the extent of damage depends on severity, age of onset, and length of time before treatment.
Signs and Symptoms
Signs and symptoms of amblyopia include asymmetric and/ or reduced visual acuity typically in one eye that is more than expected from any underlying condition and persistent after treatment. Other signs and symptoms include poor depth perception or clumsiness, and misalignment of the eye.
Causes and Risk Factors
Children are at higher risk for amblyopia if there is a family history of strabismus or amblyopia. Other risk factors in the child include media opacities, uni- or bilateral strabismus, anisometropia (asymmetric refraction, especially hyperopic), ametropia (high hyperopia or myopia), ptosis, corneal opacities, cataract(s), vitreous hemorrhage, leukocoria, or eyelid hemangioma, combined anisometropia and strabismus, Down syndrome, and premature birth. The risk is high only during a child’s period of critical development; it decreases when the child is 8-10 years old.
Diagnostic Evaluation and Differential Diagnosis
To diagnose amblyopia, evaluate acuity and refractive error on more than one occasion, starting with the amblyopic eye. Decreased or asymmetric acuity can present without amblyopia. The differential diagnosis also includes tumors, lesions, optic nerve atrophy or hypoplasia, retinal detachment, or glaucoma.
Treatment and Recommended Follow-Up
Treatment of amblyopia should first address the underlying condition (ie, strabismus surgery, refractive surgery for anisometropia, cataract, ptosis, vitrectomy, or corneal surgery). Prescription glasses can improve symptoms secondary to strabismus and anisometropia. An amblyopic eye can be strengthened or stabilized by temporarily disrupting the vision of the sound eye. Occlusion therapy (patching the sound eye) is most common, and the length of full-time wear depends on the underlying cause of the amblyopia and the patient’s age. Pharmacologic agents (eg,atropine) can also be used in the sound eye. Tape can be placed on the spectacle lens of the sound eye, or a blurry contact lens can be inserted into the sound eye. Follow-up appointments during treatment should range from 1-3 months; after treatment, follow-up appointments are necessary to ensure no regression.
Pearl to Know
Most children with unilateral amblyopia do not complain about it; they only notice it when one of their eyes is occluded. An amblyopic eye visualizes individual letters better than it does a whole line of letters.
Other Ophthalmology articles in this blog:
"A look at four common eye maladies: Arcus Senilis, Ectropion, Pterygium, and Pinguecula" by Evan Mostafa, MD and George J.Florakis, MD
"Sudden Vision Loss: An Approach to Acute Vision Loss" by Eleni Florakis and George J. Florakis, MD
More medical terms in the FibonacciMD.app Compendium (our medical encyclopedia)