Amblyopia (Lazy Eye)


Definition of Lazy Eye:

Lazy eye is a type of eye disorder in which reduced vision occurs in a seemingly healthy eye. In this condition, although the eye structure is normal, even wearing glasses do not help to correct the vision back to normal. When the vision development is normal in one eye, but abnormal in another eye, the eye whose sight has failed to develop will have a reduced vision and gradually becomes lazy. About 2 to 3 percent of children suffer from lazy eye, and the best time to correct this disorder is at infancy or early childhood. It should be noted that though only one eye is usually involved, in some cases, amblyopia can occur in both eyes at the same time. Tehran Noor Eye Hospital in Iran offers advanced treatments for lazy eye.

Lazy Eye

Lazy eye occurs due to malfunction of eyes and failure in vision development. Of course, in many cases, the causes associated with lazy eye may be hereditary. These causes are divided into the three following categories:

1. Strabismus (crossed eye): Lazy eye often occurs in strabismus. In strabismus or crossed eyes, the child uses the eye with a better vision to escape double vision, and as a result, the misaligned eye fails to develop and becomes lazy.

2. Refractive errors: These errors are among the types of visual impairment that can be corrected with prescription eyeglasses. Lazy eye occurs when there is a refractive error such as farsightedness, nearsightedness or astigmatism in one eye (while the other eye is healthy) or in both eyes (while two eyes have significantly different powers). In this case, the weaker eye develops amblyopia. Severe refractive errors in both eyes can also result in amblyopia in both eyes. It is usually difficult to diagnose this type of amblyopia, because in this case eyes appear normal and it seems that there’s nothing wrong with the child’s vision.

3. Blocked vision: Blocked vision is caused by factors such as droopy eyelid, cataracts, corneal opacity, etc. These problems are typically the reason for the most severe forms of lazy eye.


Lazy Eye Diagnosis

It is not easy to diagnose lazy eye, since parents will not notice their child's vision problem until the child has a clear problem or develops crossed eyes. The ophthalmologist also recognizes a lazy eye due to the difference in the power or the visual impairment in both eyes. Assessing visual acuity in children is difficult and the ophthalmologist needs to estimate the child's visual acuity using specific methods, such as examining how one eye fixes on and follows objects while the other eye is covered. It should be noted that poor vision in one eye is not always a sign of lazy eye, because sometimes it can be corrected with prescription eye glasses. Moreover, in some cases, other eye diseases such as cataracts, infections, tumors, and other problems in the eye result in reduced vision, which in case of their being curable, the child’s vision will be restored.

In order to correct the lazy eye, the child should learn to use his/her weaker eye. This can be accomplished by covering the more powerful eye with a patch for several weeks or months. This is the most effective way to treat lazy eye.

Even after the lazy eye is corrected, it may be necessary to cover the healthy eye for some time to prevent it from returning. In special cases based on the physician’s discretion eye drops or special lenses can be used to blur vision in the healthy eye, instead of covering the eye. Another method to treat lazy eye is the stimulation and activation of the affected eye by various methods, which is called the "active treatment" method. This technique can only be practiced at orthopedic clinics and requires multiple sessions. Another important issue is that prior to correcting the lazy eye, it’s necessary to treat all other systemic eye problems, such as correcting refractive errors with eyeglasses and treating cataract by surgical procedures.

Note: All parents should be aware of the fact that correcting the lazy eye which is caused by blocked vision such as cataracts, will only be successful if the systemic cause is diagnosed and treated in the first two to three months after birth. In Tehran-Iran Noor Eye Hospital this surgical procedure is carried out under the supervision of experienced ophthalmologists and strabismus specialists.


Important Tips

It’s recommended that all children’s vision should be examined by a physician before the age of 3. Many physicians perform vision screening for children as a part of ordinary physical examinations. Then if necessary, they refer the child to an ophthalmologist. If there’s a family history of strabismus (crossed eye), cataracts at childhood or severe eye diseases, there would be more emphasis on vision screening at infancy. Fortunately, modern methods have made vision screening of infants and young children possible. In case of early diagnosis and treatment of amblyopia, vision will be improved in most children.

The likelihood of success of amblyopia treatment is greater in the first 9 years of life. The possibility of correcting lazy eye tends to be lower after this period. Children are not generally inclined to cover their eyes and refuse to do so, but as parents, you must persuade your children to do what is best for them. Prevention and the family’s precision in implementing the physician’s orders are determinant factors in the success of lazy eye treatment.

Although newborns are able to see, their vision starts to develop from the first months. The process of visual development continues in the very first years of life until it’s completed at the age of 9. To achieve normal vision, the simultaneous development of both eyes is essential.

Additionally, parents should be familiar with the normal and expected visual behaviors of the child at different ages, in order to detect any defects in them timely. Some of these behaviors are as follows:

From birth to 1.5 months of age

During these 45 days, babies stare at the surroundings while they are awake. They can focus on light or bright objects for a few moments and blink at a camera flash. Besides, one of the eyes may sometimes be misaligned inward.

From 2 to 6 months of age

During these 4 months, the following developments occur in the child's vision system, respectively with age:

Eyes begin to track moving objects or people. The babies look at their parents when they talk to them. The babies look at their hands, at the milk bottles and, gradually, at farther objects, first while lying on the ground, then while sitting down.

From 6 months to 1 year of age

During this period, the following should be seen in your babies’ behavior:

The babies look at activities around them for longer periods of time. They look for their toys that they drop. They crawl towards their favorite toys and turn their eyes around the room to see what are happening. They answer the others’ voices and smile with their look.

From 1 to 1.5 years of age

After the age of one, babies gradually bring the objects close to their eyes in order to see them. Also, when they are told “look” or “see”, they pay attention to those very specific objects. At the age of 1.5, they look for pictures in books and find them.

From 1.5 to 3 years of age

Within this one year and a half, children gradually go through the following steps: They smile at their favorite people and objects, look at other children and imitate their movements, start painting on paper, look at the images in books and say their names.

From 3 to 4 years of age

During this time, your children can gradually draw circles (O) and plus sign (+) on paper. Later on, the children can close their eyes or blink at others’ request.

From 4 to 5 years of age

When your children become 4, they achieve hand-eye coordination. They draw objects, paint within the lines, cut simple shapes out of paper with scissors, copy some letters and shapes, put small objects in small places, have full visual awareness, pay attention to the surroundings, and talk about the objects, people or locations not present.

-What is amblyopia (lazy eye)?

-What are the causes of amblyopia?

-Is amblyopia (lazy eye) hereditary?

-What is the best age for treating lazy eye?

-What is the proper age for vision screening in children?

-Is it possible to treat a lazy eye at ages above 9?

-How long does amblyopia (lazy eye) treatment take?

-At what age is a child's vision fully developed ?



-What is amblyopia (lazy eye)?

Lazy eye is a type of visual disorder that results in a decreased central vision in an eye which seems healthy. In this case, the structure of the eye is normal, but the eye vision does not become normal even with eyeglasses.

-What are the causes of amblyopia?

Strabismus, refractive errors, vision-blocking factors. Each of these cases should be diagnosed by an ophthalmologist and after an accurate examination.

-Is amblyopia (lazy eye) hereditary?

In some cases, the genetic factors are of importance in developing lazy eye. The child should be examined carefully.

-What is the best age for treating lazy eye?

The treatment success rate is higher in the first 9 years of life.

-What is the proper age for vision screening in children?

All children under 3 should have an eye examination by a physician in order to be referred to an ophthalmologist if needed.

-Is it possible to treat a lazy eye at ages above 9?

Usually, in people above 9, the chance of treating lazy eye is very low.

-How long does amblyopia (lazy eye) treatment take?

The treatment period is determined by the ophthalmologist, but it usually takes several weeks to several months in order to achieve the desired visual outcome.

-At what age is a child 's vision fully developed?

Normally, the child's vision is fully developed from the age of 3 to 5.