Without good vision, it is hard for a child to learn about the world. Because many eye problems begin at a young age, it is important that children receive good eye care. Untreated eye problems can get worse and cause problems in school, at home and later in adult life.
What Is Amblyopia?
- Vision loss in one or both eyes,
- Not helped by glasses alone,
- Main cause of vision loss in children,
- Affects 2-3 out of every 100 children.
What Are The Causes Of Amblyopia?
1. Difference in Refractive Error Between the Eyes
There is a difference in the refractive state of the two eyes, such that one eye may be normal and not require a corrective lens, while the other eye is too nearsighted (myopic) or too farsighted (hyperopic). The condition is called Anisometropia, or difference in refractive error between the two eyes. As a consequence, the eye that needs a corrective lens will have a blurred image projected to the back of the eye (retina) and, in turn, the brain receives a blurred image from that eye. The eye (actually the brain) then becomes amblyopic. This condition is also called anisometropic amblyopia and some eye doctors may also call it refractive amblyopia. Anisometropic amblyopia is very insidious; the child looks perfectly normal but one eye is really very amblyopic. Treatment is often delayed because the parents think that the child is fine and that there is no reason to see an eye doctor for a comprehensive eye exam. As a consequence, children with anisometropic amblyopia are detected later and may have worse visual acuity and the child more difficult to treat and cure.
2. Refractive Error
When an infant or young child has an uncorrected refractive error; this is, s/he needs glasses but no one knows s/he needs glasses, the blurred vision caused by the uncorrected refractive error can lead to amblyopia in one or both eyes. About 5% of children with amblyopia have amblyopia due to an uncorrected refractive error. Again, this is why it is so important that infants and young children see an eye doctor for a comprehensive eye exam. This type of amblyopia is sometimes referred to as refractive amblyopia.
3. Misaligned Eyes
There is a difference in the alignment of the eyes such that, for example, one eye points straight ahead and the other eye turns in toward the nose or turns out away from the nose. When the eyes point in different directions, the child is “strabismic”. When one or sometimes both eyes appear to turn in the condition is called esotropia or commonly called “crossed eyes”. When one eye turns out away from the nose the condition is called exotropia or commonly called “wall-eyed”. When the eyes are not aligned, the brain will receive two very different images from the eyes and to correct this problem of double vision (diplopia) the brain will suppress or “turn-off” one of the images to achieve single vision. It is believed that this suppression or turning-off of one eye’s input to the brain leads to reduced vision in the eye that is suppressed and thus leads to amblyopia in the affected eye. Typically, it is the eye that turns in toward the nose that becomes the amblyopic eye. Often, children with exotropia, where one eye goes out, the child has the ability to look out of one eye at a time. Often, but not always, children with exotropia will not develop amblyopia (i.e., reduced vision in one eye) because the child learns to look out of both eyes, just not at the same time. Nevertheless, children with exotropia must see an eye doctor because of the obvious eye misalignment and because such eye misalignment causes reduced depth perception.
When an infant or young child has a big eye misalignment, a condition known as strabismus, the parent easily notices the eye misalignment and will take the infant or child in to the eye doctor for a comprehensive exam. Sometimes, however, the misaligned eyes may be slight and may not even be noticed by the parents. When the eyes are misaligned slightly, the condition is called a “phoria”. If one eye turns in toward the nose a little, the condition is called an “esophoria” and when an eye points out a little the condition is called an “exophoria”. Phorias typically do not cause a lazy eye to develop but there are always exceptions. Because phorias are difficult to notice, this is one more reason why a comprehensive eye exam by an eye doctor is so important.
Sometimes a child’s eyes may appear straight and at other times a child’s eyes may appear misaligned, particularly when s/he is looking at something close like a picture in a book. When the eyes become misaligned (typically one eye really turns in toward the nose) the condition is called accommodative esotropia. That is, when the child focuses or accommodates on near objects like a book the child’s eyes may become noticeably misaligned. A child with accommodative esotropia often needs glasses to see near objects clearly and to prevent the eyes from becoming misaligned. Accommodative esotropia can also be associated with amblyopia.
The fourth type of amblyopia is often referred to as deprivational amblyopia. Whenever the two eyes receive very different information or images, there is a high probability of amblyopia. For example, if a child is born with a cataract or cloudy lens such that only one eye receives a clear image and the eye with the cataract receives a blurred image, then the eye with the cataract will become amblyopic. If the infant has a problem with the cornea in one eye, or one eye has excessive matting such that the child keeps the one eye closed for a period of time – all of these conditions can lead to amblyopia. Deprivation amblyopia often develops early in life and, as a consequence, it is often the worse type of amblyopia in terms of severe loss of vision. Deprivation amblyopia is also very hard to treat effectively and often vision never becomes normal (i.e., 20/20 visual acuity).
What Is The Ohio Amblyope Registry Program?
- Provides help and supplies to children, family and eye doctors affected by lazy eye,
- Free to any Ohio child up to 18 years old
What Happens When I Sign Up My Child?
- Free educational information
- Free eye patches (limits apply),
- Free compliance items to help with patching
Can I Get Help To Pay For My Child’s Eye Exams And Treatment?
If you need help paying for eye doctor exams and treatment of your child’s lazy eye, first talk with your child’s eye doctor. Next, you may contact your local health department or the Ohio Amblyope Registry to find out about other programs.