The childhood condition of amblyopia, often called “lazy eye,” occurs when there is a loss of vision in one eye because it is ignored by the visual part of the brain. Up to 5 percent of young children are at risk for permanent vision loss from amblyopia, and it can only be treated effectively during adolescence.
Causes of amblyopia
The most common cause is refractive amblyopia, which is caused by a large refractive error (glasses strength) in one or both eyes resulting in poor development of visual function. When glasses are of unequal strength (anisometropia) from high nearsightedness (myopia), farsightedness (hyperopia), or astigmatism, the brain will not learn to see well from the eye with the stronger need for glasses. This type of amblyopia is often “invisible,” and parents may not think there is a problem because their child’s eyes look normal. This is typically discovered during a routine vision screening at the pediatrician or school.
Another common cause of amblyopia is eye misalignment, called strabismic amblyopia. In young children, the brain avoids double vision by ignoring or suppressing the vision of one eye. More rarely, there are structural problems such as a cataract or drooping eyelid that can block the vision from entering one or both eyes. If not treated very early, the condition, called deprivation amblyopia, can be the most severe and difficult to treat.
Treating amblyopia
Treatment depends first on the underlying cause. Doctors can prescribe glasses for full-time wear. Most importantly, the good eye needs to be penalized by either patching treatment or eye drops to blur the vision in the stronger eye. There is no surgery to treat amblyopia itself, but surgery may be needed to treat the underlying cause, such as cataract or eyelid surgery.
Surgery for strabismus can be performed, but ideally, the amblyopia must be treated first. Vision can usually improve until 8-10 years of age if treatment is done as recommended. After this age, the brain does not respond as well to treatment. If amblyopia is not treated, the vision in the affected eye will permanently decrease.
Access to vision services
Early detection and treatment are crucial. To expand access to care for vision services to children in the United States, the Children’s Eye Foundation of American Association for Pediatric Ophthalmology and Strabismus will launch the program All Children See, which will offer quality eye exams for all children (18 and under), regardless of socioeconomic circumstances. It will also partner with eyeglass companies, eye patching companies, and other organizations that provide any necessary follow-up care.
