Amblyopia, also known as “lazy eye,” is reduced vision – uncorrectable with lenses – in an eye that has not received adequate use during early childhood. There is no visible anatomical defect. Amblyopia has many causes. Most often it results from either a misalignment of a child’s eyes, such as crossed eyes (strabismus) or a difference in image quality between the two eyes (one eye focusing better than the other, also known as anisometropia). In both cases, one eye becomes stronger, suppressing the image of the other eye. If this condition is not treated in early childhood, the weaker eye may become permanently impaired. With early diagnosis, Amblyopia can be treated and loss of vision prevented.
What are the symptoms associated?
The most common symptoms associated with the lazy eye are:
- Eye turning in, out or up
- Closing one eye (particularly in bright sunlight)
- Headaches or eyestrain
What are the causes of Amblyopia?
Amblyopia develops because when one eye is turned, as in squint, two different pictures are sent to the brain. In a young child, the brain learns to ignore the image of the deviated eye and see only the image of the better eye.
Similarly, when there is a difference in refractive power between the two eyes, the blurred image formed by the eye with greater uncorrected power, is avoided by the brain. A moderate or high degree of refractive power is present in both eyes, when not corrected early and adequately, results in Amblyopia.
For retina to register an object, it needs adequate light and visual stimulus. In the presence of a cataract in an infant, these factors are absent; the result is Amblyopia.
In short, it develops when any of the following conditions occur in an infant or young child:
- Squint/strabismus (eyes not positioned straight)
- Congenital cataract (clouding of the lens in an infant)
- Uncorrected high nearsightedness (myopia) or farsightedness (hyperopia) in both eyes
- Uncorrected high myopia or hyperopia in one eye (one eye focuses differently from the other)
- Severe ptosis (droopy eyelids)
What are types of Amblyopia?
- Stimulus Deprivation Amblyopia: Anything that interferes with clear vision in either eye during early childhood
- Strabismic Amblyopia: In this condition, the child has strabismus, and the eyes are not aligned correctly so that one eye sees a different image from the other. In the eye that is deviated, the images seen by the brain are suppressed to avoid double vision.
- Anisometropic Amblyopia: In this, the eyes possess differing refractive powers. For example, one eye may be nearsighted while the other is farsighted or strongly astigmatic. As a result, the brain will favour the eye with the clearer image and begin to ignore signals from the other one.
What are the risk factors involved?
Children under nine years of age, whose vision is still developing, are at highest risk for Amblyopia. Generally, the younger the child, the higher the success of treatment. An older child may not achieve normal vision with treatment.
What can you do to reduce the risks?
Since Amblyopia is caused by many conditions, such as strabismus, nearsightedness (myopia) or farsightedness (hyperopia), the diagnosis and successful treatment of these vision conditions should reduce the risk of Amblyopia.
What is the treatment?
Amblyopia can often be reversed, or at least reduced if it is detected and treated early. Cooperation, of the patient and parents, is required to achieve good results. If left untreated or if not handled properly, the reduced vision of Amblyopia becomes permanent, and vision cannot be improved by any means.
The most effective way of treating Amblyopia is to encourage the child to use the amblyopic eye. Covering or patching the good eye to force use of the amblyopic eye may be necessary to ensure equal and normal vision. It can be achieved by:
- Prescribing proper spectacles if the patient is found to have a refractive error or accommodative esotropia
- Prescription of drops such as Phospholine Iodide to reduce the accommodative effort that causes accommodative esotropia
- Removal of cataract when indicated
- Occluding the normal eye, for example, with a patch
- Surgery, when Amblyopia is accompanied by strabismus and is unresponsive to conservative treatment
When occlusion is decided upon, the treatment may vary from a few hours to months or even years depending upon the age of the patient, the type and severity of Amblyopia, and the response. In cases experiencing less severe Amblyopia, partial occlusion, such as that by making one glass frosted, may be sufficient. Older children can do reading exercises at home while patching the normal eye. Those patients who are patching their eyes need periodic follow-up, which is scheduled with an optometrist or ophthalmologist.
Facts on Patching
- Patching is not a pleasant thing for a child, so initially, the child will be reluctant to undergo it. We must encourage the child to understand the importance of cooperation.
- In a young child, patching is done for shorter periods initially; the duration is increased gradually to obtain better compliance.
- Acceptance is good as soon as vision is increased in the amblyopic
Method of patching should be according to the circumstances of the child:
- The patch should be placed directly on the face over the eye.
- If the child wears glasses, the patch should be placed over the eye, not on the glasses.
- Glasses can also be used as an occluder in older children.
- Many children try to take the patch off. This problem usually disappears as the child grows accustomed to wearing the patch.
- Precautions must be taken to prevent the child from peeking around the edge of the patch.
- Patching schedules should be followed
- Patching should not be stopped The program should be tapered only by ophthalmologists or optometrists.
- Regular follow-up visits are a must.
Why should the child wear glasses when they do not improve his or her vision?
Prescription glasses will usually improve visual acuity to some extent, but not entirely. That is, the child’s vision with glasses will be better than his or her vision without them, but will not be a hundred percent or 6/6. However, the brain will gradually be trained to accept the image from the lazy eye since it will be less blurred than before. When assisted by suppressing the image from the good eye, the brain will gradually be trained to use the amblyopic eye also.
It is therefore essential to strictly wear the prescribed glasses, and adhere to the occlusion or eye patching schedule, as prescribed by your ophthalmologist, to obtain the best results. This way the vision in the lazy eye will also improve over time.
What about Amblyopia treatment in adults?
Current studies have proven that at least some improvement in the vision can be attained with Amblyopia therapy even in teenagers and young adults. Given that the treatment is non-invasive and does not cost much beyond the cost of glasses and wearing an eye patch, it must be attempted in adults also.
There is limited evidence that certain drugs like levodopa may help make lazy eye better, and you must discuss the risks and benefits of the same with your doctor.
Who is the best doctor for treating Amblyopia in Delhi?
All eye specialists or ophthalmologists are trained to take care of Amblyopia. However, the super specialists for this disease are usually trained in Pediatric Ophthalmology and Strabismus. These super specialist have had additional training in taking care of children, and the eye diseases particular to this age group. Since squint is most commonly seen in the pediatric age group and is often the cause or result of lazy eye, eye doctors who especially take care of children are also trained to manage squint.
In several parts of the world, optometrists are also trained to diagnose and manage Amblyopia under the supervision of an ophthalmologist.
More important, than the degrees your eye care professional possesses, is finding a doctor who is empathetic. A friendly doctor with excellent communication skills can establish a good rapport with the child and motivate him or her to wear glasses, and agree to eye patching, which is the cornerstone of therapy for lazy eye.
We, at Eye7 Chaudhary Eye Centre, take great pride in being a child-friendly hospital, with a team of doctors and support staff that is not only well trained in taking care of children but enjoys working with them. You can know more about our Pediatric Ophthalmology department at https://www.eye7.in/pediatric-ophthalmology/.