What is Amblyopia? A Quick Explainer

   
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May 31, 2018, by Bard Optical

Amblyopia

Amblyopia, or lazy eye, is a common childhood eye condition that is highly treatable if diagnosed early.

Cases can be so mild as to be unnoticeable or severe enough that vision loss occurs. Because the eyes do not work together, a loss of central vision in one eye is often a result of amblyopia that is left untreated. Early detection is key to treating the condition, as therapies become less effective the older a patient is.

Amblyopia occurs when vision in one or both eyes develops improperly during early childhood.

Strabismus is one specific cause. This refers to having one eye that focuses on what’s ahead, and one that points elsewhere. Often, the developing brain simply ignores the image being sent by the malfunctioning or weaker eye. Over time, if this state is not corrected, the lazy eye will not develop normal vision.

Lazy eye also can affect children born with a cataract, or cloudiness in the lens. Because part of the vision in one eye is obscured, the brain learns to rely on the vision in the healthier eye to the exclusion of the eye with the cataract. This condition becomes permanent if no intervention occurs.

Similarly, amblyopia may result from a high degree of mismatch between the refractive errors in each eye. So if a child is dramatically more nearsighted (or farsighted) in one eye as compared to the other, the brain copes by ignoring the poorer quality image. Highly pronounced astigmatism in one eye can also lead to the same result.

This interaction of eye and brain is the main reason why it is critical to detect and treat amblyopia as early as possible. The brain is especially plastic in the very young. In infants and young children who don’t see properly in one eye for any of the reasons discussed, the brain will adapt by shutting down the visual inputs from the poorer eye, learning to ignore signals from one eye.

Once lost, the brain’s ability to integrate the signals from both eyes is difficult to regain. This increases with age. That is why the American Academy of Ophthalmology recommends that “all children should have their vision checked by their pediatrician, family physician or ophthalmologist at or before their 4th birthday. If there is a family history of misaligned eyes, childhood cataracts or serious eye disease, an ophthalmologist should check their eyes when they are an infant.”

Early intervention matters. The American Optometric Association identifies six months as the appropriate age for a first vision check, with a recheck by age 3.

No matter the cause of the lazy eye, amblyopia is treated similarly in most cases. The main principle is that the weaker eye must be strengthened, so the eye with stronger vision is covered with a patch. The child’s brain then must rely on the signals coming from the weaker eye, instead of ignoring those signals. Prisms or vision therapy can also be incorporated into treatment to increase reliance on the weaker eye.

In some cases, the same result can be accomplished by putting drops in the stronger eye to make vision there blurry. This also forces the brain to rely more on the vision in the weaker eye. In the case of more pronounced nearsightedness or farsightedness (or sometimes astigmatism) in one of the eyes, glasses will be the prescribed treatment. The glasses will bring the vision in the bad eye on par with the other eye so that they can function together, and the brain adapts to inputs from both.

Sometimes surgery might be necessary to correct more severe problems in one eye. Following surgery, a patch is usually recommended to continue the therapeutic effects. Several weeks or months of wearing a patch or using drops might be necessary to strengthen the weaker eye.

Compliance with wearing a patch may be difficult in young children, but this therapy is crucial to preventing lifelong vision issues. Crucially, “Lazy eye will not go away on its own. If not diagnosed until the preteen, teen or adult years, treatment takes longer and is often less effective,” according to the American Optometric Association. While some children might bump into objects or have other noticeable symptoms, others may show fewer indicators to parents and caregivers of an issue. Fortunately, however, amblyopia is a very treatable condition if diagnosed early.

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