What is lazy eye?
What is a lazy eye?
Lazy eye, which doctors call amblyopia, happens when the vision in one eye doesn't develop properly during childhood. The brain leans on the stronger eye to take in what it sees. As a consequence, the weaker eye gets even worse, with the potential to cause permanent vision issues.
Lazy eye is the leading cause of binocular vision problems in children under the age of 7. The good news: If amblyopia is diagnosed and treated quickly, you can avoid long-term problems.
Definition and characteristics of lazy eye
A child with lazy eye typically has normal vision in the good eye but blurred vision in the other eye. The lazy eye may wander from side to side, and the eyes might not track together. The child might even have crossed eyes. It's also possible to have lazy eye without any obvious symptoms.
Types of lazy eye: strabismic and refractive amblyopia
The two most common types of lazy eye in children are strabismic and refractive amblyopia. Strabismic amblyopia occurs when the eyes don't develop evenly or aren't straight. One eye may face in a slightly different direction than the other, so the brain starts to ignore it.
Refractive amblyopia occurs when the ability to see differs greatly between a child's two eyes. If a child has a great deal of refractive error (which refers to the strength of corrective lenses needed) in one eye, the brain can't learn to see with that eye.
Prevalence and age of onset
About 2% to 4% of kids under the age of 15 have lazy eye. The condition starts in childhood, usually by the age of 6. If you can identify it and start treatment by age 7, you have the best chance of correcting it completely.
Causes of lazy eye
Lazy eye occurs when the nerve pathways connecting the retina (the structure at the back of the eye) to the brain don't develop normally. Anything that creates poor vision in one eye or that causes one eye to wander or cross can cause lazy eye. Once amblyopic eye begins, the brain starts to ignore signals from the weak eye, relying on only the stronger eye for vision.
Strabismus and misaligned eyes
Eyes are supposed to line up together and point in the same direction — but sometimes they don't. If the eye muscles don't work in synch, the eyes might cross or one of them might turn out or up or down — really, in any direction.
When this occurs, the brain gets two images and starts seeing double. Because this is confusing, the brain simply tunes out the image from the wandering eye. That eye, as a result, may not develop properly.
Refractive errors and uncorrected vision
If a child's vision is very nearsighted or farsighted, visual acuity can be affected. Just as with strabismus, the brain ignores the poor vision signal it gets from the affected eye, so that eye doesn't develop properly. This type of lazy eye can be harder to spot, since your child's eyes look okay.
Factors affecting visual development
Some children have risk factors that can cause lazy eye, including:
- Premature birth
- Various developmental disabilities
- Small birth weight
- Family history of lazy eye
In addition, some children have rare eye conditions that can result in lazy eye. These can include cataracts, which are cloudy lenses that create reduced vision, as well as droopy eyelids or scarring on the cornea. Any long-term blurring of vision can result in the brain imbalance that causes lazy eye. This type of lazy eye is known as deprivation amblyopia.
Amblyopia: the effects and diagnosis
Many children with lazy eye go undiagnosed for a long time. Parents need to pay attention to things that might seem normal. Did you assume that your child bumps into furniture a lot because they're uncoordinated? Maybe they actually have lazy eye.
Vision impairment and reduced visual acuity
Does your child have trouble telling how far away things are (swinging and whiffing at T-ball, for example)? Do they squint or shut the same eye all the time? Do they turn their head or tilt it to see things? All these are signs that it's time for an eye exam. Your pediatrician can perform a basic eye exam and refer you to a pediatric ophthalmology specialist if needed.
Detecting lazy eye: screen and eye examinations
Your child's eye exam should include:
- Dilating the eye for a close exam
- Covering each eye to see whether it can follow a moving object
- Asking the child to identify letters, symbols, or pictures across a room
These tests show the doctor whether both eyes can see well, whether each eye can move as it should and whether anything is blocking light in the eye. If there's a problem, it doesn't necessarily mean your child has lazy eye — they might just need glasses for better vision.
Differential diagnosis and other vision disorders
In a differential diagnosis, a doctor is faced with symptoms that could point to a range of several disorders. Your doctor may need to differentiate between the types of amblyopia to plan for treatment. The symptoms of amblyopia can overlap with symptoms of some rarer eye diseases, including problems with the optic nerve and retina.
Treating lazy eye (amblyopia)
The earlier you can start lazy eye treatment, the better. If you don't start in time, you may not be able to correct the condition. Only about half of older kids (between 7 and 17) respond to amblyopia treatment, which may include eye patches, glasses, eye exercises, and, in rare cases, surgery.
Patching therapy
There's a good chance your child's lazy eye treatment will involve patching the stronger eye. This forces the brain to use the weak eye, which gradually makes that eye stronger. Your child may have to wear the patch for many hours a day, and the treatment could last several months.
Your doctor might recommend some less obvious types of patching. Eye drops that contain atropine can blur the stronger eye and force your child's brain to use the weaker eye. If your child wears glasses, a Bangerter filter over the eyeglass lens creates blurring over the better eye, forcing that weaker eye to do more work.
Make sure your child isn't finding a way to peek around the patch. And if they object to wearing a patch, just remind them how cool pirates are.
Corrective eyewear: glasses and contact lenses
If your child has refractive amblyopia, eyeglasses that correct nearsightedness or farsightedness may be the primary treatment needed. Older children may be able to opt for contact lenses.
Vision therapy and binocular training
In some cases, your ophthalmologist will recommend vision therapy, which may include activities your child finds fun. Coloring inside the lines turns out to be a great task for training your eyes. Holding an object near the nose and focusing on it as you move it closer and farther away is another helpful exercise.
Surgical interventions
If your child's amblyopia is caused by cataracts (rare in children) or droopy eyelids, your doctor may recommend surgery. In the same way, some children with strabismus (crossed eyes) can benefit from eye muscle surgery. However, surgery is rarely the treatment of choice for lazy eye.
What to do if your child has a lazy eye
You can't keep lazy eye from happening, but you can stop it from getting worse. Early detection and diagnosis are key to eye health, so make sure your child has an eye exam as an infant and again before the age of 3. Remember, amblyopia can recur, so keep up with regular eye care as your child grows toward adulthood.
Frequently asked questions
Can lazy eye be corrected in adults?
Lazy eye treatment in teens and adults isn't as successful as with children. Adults with lazy eye can end up with permanent blurred vision, vision loss, and other eye conditions, including dry eye. Start treatment as early as possible.
How long does lazy eye treatment usually take?
Expect many weeks or months of treatment to correct lazy eye. Some people need to wear eye patches part-time for several years to keep the weak eye from getting worse again.
Are there any alternative treatments for lazy eye?
New treatments being tried involve watching videos through a virtual reality (VR) headset to force use of the weaker eye.
Can lazy eye develop in both eyes?
Yes, but this is quite rare.