Amblyopia or low vision, also known as “lazy eye”, is an eye developmental disorder in which the eye does not develop normal visual acuity, even with glasses or contact lenses. Low vision begins during early childhood.
In most cases, only one eye is affected, but in some cases, reduced visual acuity can occur in both eyes. If low vision is detected early in childhood and treated correctly, vision loss can be avoided. But if left untreated, low vision can cause serious vision problems, including “legal blindness.”
Signs and symptoms of low vision
As amblyopia is a typical problem of young children, the symptoms may go unnoticed. Amblyopia is often associated with strabismus . If you notice that your child is ” cross-eyed “ , immediately schedule a visit to an eye specialist who specializes in children’s vision.
Simple signs that your child has a lazy eye
One of the signs that your child has amblyopia is crying or agitation when you cover one eye. You can try this simple test at home by simply covering and uncovering your child’s eye (each separately) when he is performing a visual task, such as ordinary television viewing.
If your child does not worry when one eye is covered, but becomes agitated when the other eye is, this may indicate that the eye you covered is correct, and that the uncovered eye is amblyopic, causing blurred vision. But this kind of test is not a substitute for a detailed eye examination . Have your child’s vision checked by an eye specialist to make sure they can see well in both eyes and that the eyes are working properly.
What causes low vision?
There are three types of amblyopia, based on different causes:
1. Strabismic amblyopia
Strabismus is the most common cause of amblyopia. In order to avoid poor vision, the brain ignores the visual input from the damaged eye, putting that eye into a state of amblyopia. This type of amblyopia is called strabismic amblyopia.
2. Refractive amblyopia
Sometimes amblyopia is caused by uneven refractive errors in the two eyes. For example, one eye can be significantly short-sighted or far-sighted , while the other is not needed, as well as one eye can have severe astigmatism , while the other eye can be completely healthy. In such cases, the brain relies on the healthier eye and “turns off” the blurred vision coming from the other eye, thus causing amblyopia. This type of amblyopia is called refractive amblyopia.
3. Deprivation amblyopia
This is a type of low vision caused by something preventing light from entering and focusing in the child’s eye, such as a congenital cataract . Rapid treatment of congenital cataracts is necessary in order for the child to develop normal vision.
Treatment of low vision
In some cases of refractive amblyopia , normal vision can be achieved by simply correcting the refractive errors in both eyes using glasses or contact lenses . It is often necessary to bandage the healthy eye in order for the brain to focus on the signals from the amblyopic eye and thus enable the normal development of vision in that eye.
Treatment of strabismic amblyopia
It usually involves surgery to straighten the eyes and the use of an eye bandage and some form of eye therapy (orthoptics). In this way, it is tried to achieve that both eyes work together as a team.
Amblyopia due to anopsia
Amblyopia due to disuse (anopsia) occurs when the transparent media of the eye becomes cloudy, as in the case of cataracts or corneal scarring. The creation of an image in the eye and the development of a part of the brain are hindered. Sometimes ptosis (drooping eyelids) or another disorder that interferes with a child’s vision can result in amblyopia.
Wearing a bandage can last a few hours a day or a whole day, weeks or months. If your child has problems wearing an eye patch, you might consider specially designed contact lenses that prevent light from entering the healthy eye, but do not affect your child’s appearance. Although such lenses are more expensive than an ordinary eye patch, they can be very useful in more severe cases of amblyopia, where there is resistance to the eye patch.
In some children, atropine eye drops are also used to treat amblyopia. In order to blur the vision in the healthy eye, the eye is dropped every day. In this way, the eye with amblyopia is forced to exert more effort in order to strengthen it. The advantage of this method of treatment is that you will not have to be constantly aware of whether or not your child is wearing an eye patch.
In one of the larger studies involving 419 children under 7 years of age with amblyopia, with visual acuity of 20/40 to 20/100 before treatment, atropine therapy produced similar results to eye patch treatment (with visual acuity in the amblyopic eye it was slightly higher in the group that wore a bandage). As a consequence, some eye specialists, previously skeptical, began to use atropine as a first-line treatment for amblyopia.
It is important to mention that atropine drops have some side effects: sensitivity to light, tearing of the eye and possible paralysis of the ciliary muscle after long-term use of atropine, which can affect the accommodation of the eye or the ability to change focus.
Helping older children and adults with amblyopia
For years, experts believed that if treatment was not started in childhood, it was not possible to achieve improvements later in life. It was believed that the critical period is the age of about 8 years . But it appears that older children and even adults with long-term amblyopia may benefit from treatment that uses a computer program to stimulate neural changes, leading to improvements in visual acuity and contrast sensitivity.
One such program – RevitalVision – has improved vision in older children and adults with long-term amblyopia. The treatment consists of 40 appointments in the form of training lasting 40 minutes over several weeks.
In one clinical study involving 44 children and adults with amblyopia aged 9-54 years, 70.5% of participants improved visual acuity by two or more lines on a standardized vision test after completing RevitalVision treatment.
Early detection and treatment are paramount
Although the latest treatments can improve vision in older children and adults, most experts agree that early detection and treatment of amblyopia is critical to normal vision development. Amblyopia will not go away on its own, and untreated this condition leads to serious, permanent vision problems. In the event that your child’s stronger eye is damaged for some reason later in life, their vision will be poor due to an amblyopic eye, so it is best to treat amblyopia as soon as possible.
In some cases, uncorrected refractive errors and amblyopia can lead adults to draw false conclusions about children’s development. In 2012, a girl named Emmelyn Roettger was accepted into Mensa as the youngest member, aged 3. But when she was 9 months old, she did not crawl or reach for objects, and some of the doctors wondered if she might have autism. Fortunately, her mother took her for an eye exam, where she was found to have farsightedness and amblyopia. With glasses and a bandage over her eye, she began to interact normally with her environment and learn quickly.
Without an eye examination and treatment, this little girl’s life could have taken a different path.
New hope for the treatment of amblyopia in adults
Amblyopia is a visual developmental disorder in which the vision of one eye does not develop properly in early childhood. The problem is not in the eye itself, but in the visual parts of the brain.
A hindering factor in early visual development can be due to misalignment of one eye or because the eye lacks focus. Later, when the misalignment or focus is corrected, the visual deficit persists.
Treatment for the past 200 years has involved connecting the healthy eye to make the “lazy eye” work. Until recently, the eye was bandaged all day, and lately it has been recommended 3-6 hours a day. In most cases, this treatment did bring improvements in vision, but there was great variability among cases.
Results after 6 months to 2 years of blindfolding show improved functioning in most cases, but after the blindfold is removed, the eyes usually do not work in coordination and there are problems with three-dimensional vision. The stronger eye overpowers the weaker one – amblyopic, which leads to reduced visual acuity.
What is very important to mention is that there is a limited time to react to amblyopia. This treatment works until the age of 12. There is no treatment for adults suffering from amblyopia.
The current approach to the problem is based on the assumption that amblyopia is the primary problem, while loss of binocular function is a secondary consequence. There is reason to believe that the logic should be reversed.
The primary problem would be that the two eyes, either due to misalignment or the eye with weaker focus, stop working together, while the secondary problem would then be amblyopia. The connection between irregular binocular vision and amblyopia is the weakening of the vision of one eye.
All people with amblyopia have some degree of impairment where the stronger eye suppresses the functioning of the weaker eye to avoid double vision or blurred vision.
Over time, it is understood that this constant suppression leads to permanent vision loss or amblyopia.
This new way of thinking about the cause of amblyopia leads to a different way of treatment, one that primarily deals with the loss of binocular function in the first step, with the expectation that over time the eye with amblyopia will improve due to reduced dominance of the stronger eye.
Recently, suppression measurement tools have been produced that show a direct relationship between suppression and amblyopia. With this new way of thinking about this problem, a method was developed to measure the degree of eye suppression and to determine the degree of visibility through a method that shows different objects to each eye where the suppression would be minimal.
As a result of these artificial (compared to natural vision) visual conditions, it was established that both eyes can combine information in a normal way. The more time the eyes work together combining information (for the first time), their binocular capacity becomes stronger and after a while, the vision conditions can be normalized and both eyes can see the object in the same way.
Binocular training should be done 1-2 hours a day for 4-6 weeks, after which both eyes could cooperate together under natural visual conditions. Improvements in three-dimensional vision were also found, which some patients experienced for the first time in their lives. The visual acuity of the amblyopic eye is also improved as a result of eliminating the suppression of the other eye.
What is particularly important is that these results were achieved in adults, for whom until now it was considered that there was no successful treatment.
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