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Children's Vision Initiative
Amblyopia or Lazy Eye
Amblyopia is decreased vision in one or both eyes due to abnormal development of vision in infancy or childhood. In amblyopia, there may not be an obvious problem of the eye. Vision loss occurs because nerve pathways between the brain and the eye aren't properly stimulated. The brain “learns” to see only blurry images with the amblyopic eye even when glasses are used. As a result, the brain favors one eye, usually due to poor vision in the other eye. Another word for amblyopia is often “lazy eye.” It is the leading cause of vision loss amongst children.
Refractive amblyopia happens when there is a large or unequal amount of refractive error (glasses strength) between a child's eyes. The brain learns how to see well from the eye that has less need for glasses and does NOT learn to see well from the eye that has a greater need for glasses. The vision problem may be invisible because the child does not complain of blurry vision. The child sees well with the better seeing eye. Additionally, the amblyopic eye may not look any different from the normal seeing eye. Therefore, parents and pediatricians may not think there is a problem because the child’s eyes look normal. For these reasons, this kind of amblyopia in children may not be found until the child has a vision test. This kind of amblyopia can affect one or both eyes and can be best helped if the problem is found early.Will glasses help a child with amblyopia to see better?Glasses may improve visual acuity to some degree but usually not completely. With amblyopia, the brain is “used to” seeing a blurry image and needs to learn how to see better with that eye.. With time, however, the brain may “re-learn” how to see and the vision may increase. The normal eye is treated (most often with patching or eyedrops) to make the amblyopic (weak) eye stronger.
When should amblyopia be treated?
Early treatment is always best. If necessary, children with refractive errors (nearsightedness, farsightedness or astigmatism) can wear glasses or contact lenses when they are as young as one week old. Children with cataracts or other “amblyogenic” conditions are usually treated promptly in order to minimize the development of amblyopia.
How old is TOO old for amblyopia treatment?
A recent National Institutes of Health (NIH) study confirmed that SOME improvement in vision can be attained with amblyopia therapy initiated in younger teenagers (through age 17 years). Better treatment success is achieved when treatment starts early, however.
How can I get early treatment for amblyopia?
Some forms of amblyopia, such as that associated with large-deviation strabismus, may be easily detected by parents. Other types of amblyopia (from high refractive error) might cause a child to move very close to objects or squint his or her eyes. Still other forms of amblyopia may NOT be obvious to parents and therefore must be detected by Vision Screening.
What is Vision Screening?
Vision Screening is strongly recommended over the course of childhood to detect amblyopia early enough to allow successful treatment. Pediatricians check newborns for red reflex to find congenital cataracts. Infants are checked for the ability to fix and follow and whether they have strabismus. Toddlers can have their pupillary red reflexes tested with a direct ophthalmoscope (Brückner Test) or by instruments that identify a significant refractive error that needs correction to prevent amblyopia. When children can consistently identify objects either by reading or by matching, the acuity of each eye (with the non-tested eye patched) is screened to identify amblyopia.
How is amblyopia treated?
One of the most important treatments of amblyopia is correcting the refractive error with consistent use of glasses and/or contact lenses. Other mainstays of amblyopia treatment are to enable as clear an image as possible (for example, by removing a cataract), and forcing the child to use the weaker eye (via patching or eye drops to blur the better-seeing eye).
When should patching be used for amblyopia treatment?
Patching should only be done if an ophthalmologist recommends it. An ophthalmologist should regularly check how the patch is affecting the child’s vision. Although it can be hard to do, patching usually works very well if started early enough and if the parents and child follow the patching instructions carefully. It is important to patch the better seeing eye to allow the weak eye to get stronger.
Are there different types of patches?
The classic patch is an adhesive "Band-Aid" which is applied directly to the skin around the eye . They are available in different sizes for younger and older children. For children wearing glasses, both cloth and semi-transparent stickers (Bangerter foils) may be placed over or onto the spectacles. "Pirate" patches on elastic bands are especially prone to "peeking" and are therefore only occasionally appropriate.
Is there an alternative to patching to treat amblyopia?
Sometimes the stronger (good) eye can be “penalized” or blurred to help the weaker eye get stronger. Atropine drops will temporally blur the vision in the good eye This forces the child to use the weaker eye. Ophthalmologists use this treatment instead of patching when the amblyopia is not very bad or when a child is unable to wear the patch as recommended. For mild to moderate degrees of amblyopia, studies have shown that patching or eye drops may be similarly effective. Your pediatric ophthalmologist will help you select what treatment regimen is best for your child.
Do drops work for all amblyopic children?
Not all children benefit from eye drop treatment for amblyopia. Penalizing eye drops (such as atropine) do not work as well when the stronger eye is nearsighted.
How many hours per day patching is enough when treating amblyopia?
The mainstay of treating amblyopia is patching of the dominant (good) eye, either full or part-time during waking hours. The prescribed number of hours of patching will depend on the visual acuity in the amblyopic eye and whether treatment has been successful in the past. Your doctor will prescribe the appropriate time for you.
How long does amblyopia patching therapy take to work?
Although vision improvement frequently occurs within weeks of beginning patching treatment, optimal results often take many months. Once vision has been improved, less (maintenance) patching or periodic use of atropine eyedrops may be required to keep the vision from slipping or deteriorating. This maintenance treatment may be advisable for several months to years.
During which activities should patching be performed?
There is no particular activity that will improve the vision more than another activity. The most important part of treatment is keeping the patch on for the prescribed treatment time. As long as the child is conscious and has his or her eyes open, visual input will be processed by the amblyopic eye. On the other hand, the child may be more cooperative or more open to bargaining if patching is performed during certain, favorite activities (such as watching a preferred television program or video). Some eye doctors believe that the performance of near activities (reading, coloring, hand-held computer games) during treatment may be more stimulating to the brain and produce better or more rapid recovery of vision.
Should patching be performed during school hours?
In many instances, school is an excellent time to patch, taking advantage of a nonparental authority figure. Patching during school hours gives the class an opportunity to learn valuable lessons about accepting differences between children. While in most instances, children may not need to modify their school activities while patching, sometimes adjustments such as sitting in the front row of the classroom will be necessary. If the patient, teacher, and classmates are educated appropriately, school patching need not be a socially stigmatizing experience. On the other hand, frequently a parental or other family figure may be more vigilant in monitoring patching than is possible in the school setting. Parents should be flexible in choosing when to schedule patching.
What if my child refuses to wear the patch?
Many children will resist wearing a patch at first. Successful patching may require persistence and plenty of encouragement from family members, neighbors, teachers, etc. Children will often throw a temper-tantrum, but then they eventually learn not to remove the patch. Another way to help is to provide a reward to the child for keeping the patch on for the prescribed time period.
Can surgery be performed to treat amblyopia?
There is no surgery to improve the vision for amblyopia. Surgery can be performed to straighten misaligned eyes such as crossing. Surgery to make the eyes straight can only help enable the eyes to work together as a team. Children with strabismic amblyopia still need close monitoring and treatment for the amblyopia, and this treatment is usually performed before strabismus surgery is considered.
Children who are born with cataracts may need surgery to take out the cataracts. After surgery, the child will usually need vision correction with glasses or contact lenses and patching.
What are appropriate goals of amblyopia treatment?
|In all cases, the goal is the best possible vision in each eye. While not every child can be improved to 20/20, most can obtain a substantial improvement in vision. The earlier the treatment for amblyopia, the more successful the treatment tends to be.
What happens if amblyopia treatment does not work?
In some cases, treatment for amblyopia may not succeed in substantially improving vision. It is hard to decide to stop treatment, but sometimes it is best for both the child and the family. Children who have amblyopia in one eye and good vision only in their other eye can wear safety glasses and sports goggles to protect the normal eye from injury. As long as the good eye stays healthy, these children function normally in most aspects of society
Retinopathy of Prematurity (ROP)
Retinopathy of prematurity (ROP) is a potentially blinding disease caused by abnormal development of retinal blood vessels in premature infants. The retina is the inner layer of the eye that receives light and turns it into visual messages that are sent to the brain. When a baby is born prematurely, the retinal blood vessels can grow abnormally. Most ROP resolves without causing damage to the retina. When ROP is severe, it can cause the retina to pull away or detach from the wall of the eye and possibly cause blindness. Babies 1500 grams or less and are born before 35 weeks gestation are at highest risk.
What determines the severity of ROP?
Birth weight and gestational age are the most important risk factors for development of severe ROP. Other factors that are associated with the presence of ROP include anemia, poor weight gain, blood transfusion, respiratory distress, breathing difficulties and the overall health of the infant. There is active research into the correlation of levels of growth factors in the blood and ROP. Close monitoring has decreased the impact of oxygen use as a risk factor for development of ROP. Light levels do not affect severity of ROP.
How is ROP diagnosed?
Ophthalmologists (Eye MD’s) who are skilled in the evaluation of infant eyes make the diagnosis of ROP. They examine the eyes after the pupils are dilated with drops. There is active research which is evaluating the effectiveness of digital photography for diagnosing ROP. Infants less than 1500 grams (3.3 lbs) and with a gestational age less than 31 weeks undergo eye examinations to monitor for ROP
How do doctors describe ROP?
ROP is described by its location in the eye (the zone), by the severity of the disease (the stage) and by the appearance of the retinal vessels (plus disease). The first stage of ROP is a demarcation line that separates normal from premature retina. Stage 2 is a ridge which had height and width. Stage 3 is growth of fragile new abnormal blood vessels. As ROP progresses the blood vessels may engorge and become tortuous (plus disease)
Who requires treatment?
When ROP reaches a certain level of severity, called type 1, the potential for retinal detachment (and possible permanent vision loss) becomes great enough to warrant consideration of laser treatment. Eyes that develop this disease have type 1 ROP and are usually treated.
Typically, injection inside eye and or laser ablation is applied to the immature portion of the retina
The outcome of injection or laser treatment is usually favorable with disappearance of the abnormal blood vessels and resolution of plus disease. Despite accurate diagnosis and timely laser treatment, the ROP sometimes continues to worsen and the retina pulls away from the back of the eye. Eyes with retinal detachment caused by ROP generally have a poor visual prognosis. Retinal detachment can be treated with vitrectomy and/or scleral buckling procedure. Despite optimal treatment, some eyes with ROP progress to permanent and severe vision loss.
Why are eye exams recommended after discharge from the hospital?
It is VERY IMPORTANT to have eye exams after discharge from the hospital since ROP may not be resolved before discharge. Also, even with successful treatment of ROP, prematurity may lead to other vision abnormalities. Prematurity is a risk factor for the development ofamblyopia (lazy eye), eye misalignment (strabismus), the need for glasses (even at a young age), and cortical visual impairment. Therefore, every premature infant needs the long-term attention of an ophthalmologist
Refractive errors
How does the eye focus light?
In order to see clearly, light rays from an object must focus onto the inner back layer of the eye . The eye works like a camera. It has an opening at the front (the pupil), a focusing mechanism (the cornea and crystalline lens), and a light-sensing portion at the back (the retina). If light rays are not focused on the retina, a refractive error is present.
The refractive errors are: myopia, hyperopia and astigmatism
More technical information on refractive error may be found on the EyeWiki Site.
Why does a child need glasses?
Children may need glasses for several reasons—some of which are different than for adults. Because a child’s visual system is growing and developing, especially during the first 5-6 years of life, glasses may play an important role in ensuring normal development of vision. The main reasons a child may need glasses are:
• To provide better vision, so that a child may function better in his/her environment
• To help straighten the eyes when they are crossed or misaligned (strabismus)
• To help strengthen the vision of a weak eye (amblyopia or “lazy eye”). This may occur when there is a difference in prescription between the two eyes (anisometropia). For example, one eye may be normal, while the other eye may have a significant need for glasses caused by near-sightedness, far-sightedness or astigmatism.
• To provide protection for one eye if the other eye has poor vision
To protect eyes from injuries
How can a child be tested for glasses, especially in infancy or early childhood?
An ophthalmologist can detect the need for glasses through a complete eye exam. Typically, the pupils are dilated in order to relax the focusing muscles, so that an accurate measurement can be obtained. By using a special instrument, called a retinoscope, your eye doctor can arrive at an accurate prescription. The ophthalmologist will then advise parents whether there is a need for glasses, or whether the condition can be monitored.
What are the different types of refractive errors (need for glasses) that can affect children?
There are 4 basic types of refractive errors:
• Myopia (near-sighted) – This is a condition where the distance vision is blurred, but a child can usually see well for reading or other near tasks. This occurs most often in school-age children, although occasionally younger children can be affected. The prescription for glasses will indicate a minus sign before the prescription (for example, -2.00). If the myopia is slight, allowing a child to sit a little closer to the front of the classroom may be an alternative.
• Hyperopia (far-sighted) – Most children are far-sighted early in life (this is normal!) and need no treatment for this because they can use their own focusing muscles to provide clear vision for both distance and near vision. Glasses are rarely needed if the far-sightedness is less than +1.00 or even +2.00. When an excessive amount of far-sightedness is present, the focusing muscles may not be able to keep the vision clear. As a result of this, problems such as crossing of the eyes, blurred vision, or discomfort , amblyopia or lazy eye may develop. A prescription for hyperopia will be preceded by a plus sign (for example, +3.00).
• Astigmatism – Astigmatism is caused by a difference in the surface curvature of the eye. Instead of being shaped like a perfect sphere (like a basketball), the eye is shaped with a greater curve in one axis (like a football). If your child has a significant astigmatism, fine details may look blurred or distorted. Glasses that are prescribed for astigmatism have greater strength in one direction of the lens than in the opposite direction. A prescription for astigmatism will have several numbers and will look something like this: -2.00 +2.50 X 90.
• Anisometropia – Some children may have a different prescription in each eye. This can create a condition called amblyopia, where the vision in one eye does not develop normally. Glasses (and sometimes patching or eye drops) are needed to insure that each eye can see clearly.
How will I ever get my child to wear glasses?
That is a question most parents ask, especially when their child is an infant or toddler. The best answer is that most young children who really need glasses will wear their glasses without a problem (happily) because they do make a difference in their vision. Initially, some children may show some resistance to wearing their glasses, but it is necessary for parents to demonstrate a positive attitude. If the child does not cooperate, the doctor may prescribe eye drops in an attempt to help the child adjust to the glasses. Toddlers often may wear the glasses only when they are in a good mood and reject them (and everything else) when they are not. School age children and their parents can provide input into the decision regarding the need for glasses. Some children may have small refractive errors that do not require glasses, while others may voice concern about difficulties in the classroom.
Does my child need bifocals?
Children rarely need bifocals. Occasionally, children who have crossed eyes (esotropia) may need to have bifocals to help control the crossing. Also, children who have had cataract surgery usually need bifocals or reading glasses.
Will wearing glasses make my child’s eyes worse or more dependent on them?
No. In fact, the opposite may be true. If a child does not wear the glasses prescribed, normal vision development can be adversely affected.
What are some things I can do to help my child adjust to glasses?
Getting a good frame fit by an optician who is experienced in pediatric eyewear is of great importance. The frame should be very comfortable with the eye centered in the middle of the lens. The frame should look like it fits the child now — not one that he/she will grow into in a year.Lenses made of a material called polycarbonate will provide the best protection for your child because this lens material is shatterproof. Many children’s frames have soft, comfort-cables that fit around the ears.
Adding elastic bands or silicone temple tips are simple additions that can help keep glasses in the correct position on a child’s face. Most children will wear glasses well if the prescription is correct and should adjust to the glasses within two weeks. If your child continues to complain that “I can’t see in my glasses” or constantly looks over the glasses call your physician.
What do I do about sports and swimming now that my child needs glasses?
There are glasses specifically made for sports (recreational glasses) that are a great option. Ask your optician about prescription swim goggles. They are often not as expensive as you might think.
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