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Lazy Eye (Amblyopia)

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Overview of lazy eye or amblyopia

Lazy eye or amblyopia is the condition when one of the eyes in a person does not develop properly resulting in poor image quality or loss of vision from that eye. Lazy eye often leads to a condition where both the eyes cannot be used satisfactorily. Lazy eye is not a disease and what causes this problem is unknown. Lazy eye is the leading cause of decreased vision among children and if untreated, vision loss may range from mild to severe.

 

Symptoms of lazy eye or amblyopia

It is difficult to ascertain the cases of amblyopia since it affects young children who may not be able to communicate the problems they face. In most cases of lazy eye there are no symptoms and it may be hard to determine a sign for the problem. However, certain symptoms like a child straining look around, having a squint and not being able to gauge depth or the correct distance are mainly reported. Ocular conditions such as lazy eyes limit the binocular vision of the eyes and impair depth perception.           

 

Causes of lazy eye or amblyopia

There can be different causes for development of lazy eyes including 

Ocular misalignment (strabismus)

Misaligned eyes or wandering eyes is the most common cause of amblyopia. In such a condition both the eyes maybe looking at different points and direction, with each of the eye seeing a different image. The resultant image causes confusion in the way the brain perceives the image and tends to use the image formed by the better eye. In a newborn both the eyes are not used together immediately but in due course of time they start functioning as one and the brain works normally to fuse the image they see. In cases of strabismus each eye starts looking at different angles and the brain does not correct the image. If this condition persists for sometime the weak eye will suffer as the eye will not connect properly to the visual cortex of the brain and amblyopia will result. This type of condition often leads loss of depth perception and cannot be corrected by a surgery.

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Refractive errors

Aanisometropia – If the light rays are not focused on the retina or the lens of the eye a refractive error can happen. This can happen when one eye is suffering from a greater degree of myopia (nearsightedness) compared to the other eye or one eye is suffering from greater degree of hyperopia (farsightedness) when compared to the other eye. 

Astigmatism - Another refractive error is a condition called astigmatism where the vision is fuzzy due to an uneven nature of the cornea. Refractive errors are not caused due to any disease and cannot be prevented. They can, however, be managed with glasses, lenses and sometimes a surgery.           


Difficulty is sight due to obstruction

Sometimes an obstruction can cause the image from one eye to be cloudy and unclear. This may also lead to amblyopia. A disorder like cataract, glaucoma or corneal ulcer, prevents the image from forming clearly on a retina, leading to a condition of a child developing lazy eyes.

 

Diagnosis of lazy eye or amblyopia

There are no imaging tests to be done to diagnose a lazy eye and an ophthalmologist normally relies on a physical verification of the eye. A doctor looks for conditions where a child or patient has to try very hard to see an object. Sometimes it maybe a squint and at times the inability to measure correctly the distance to an object. 

Some tests that can diagnose lazy eyes include the red reflex text for newborns. This diagnosis technique, conducted with the help of a lighted magnifying device called ophthalmoscope, is useful to diagnose problems like cataracts, glaucoma and anything that can be blocking the optical pathway. In younger children a test is conducted that covers each eye in turn to see if this makes them upset due to loss of normal vision. In children who can talk a similar test is conducted with a chart containing symbols of different sizes of objects.

 

Treatment of lazy eye or amblyopia

After a lazy eye is diagnosed according to NHS UK there are two choices to treatment. If the condition is caused due to a problem like cataract, it is necessary to address that issue. If nothing is impeding the optical pathway, the treatment is centered around getting the affected eye to work harder so that connecting eye tissues can develop and improve vision. 

1. Treating underlying eye problems

Use of glasses: Use of glasses is the foremost way to treat lazy eyes. It can effectively treat cases of myopia and hyperopia if worn constantly. 

Surgery: In cases where the vision is blocked due to a disease like cataracts a surgery can be carried out. Cataract surgeries have a very good success rate and are simple surgery for modern healthcare.

2. Encouraging the use of the eye:

Using patch:

This type of treatment takes a longer time and success of the procedure is not certain. The leading method to encourage the use of a lazy eye is the use of a patch. In this method a patch which blocks the vision is places on the good eye. This forces the lazy eye to work for the brain to perceive an image. It can be very effective in improving the sight in the lazy eye but a child can be resistant to using a patch.

Atropine eye drops:  Another method which works on the same principle but does not contain the stigma of using a patch is the use of atropine eye drops. These eye drops blur the vision in the good eye by dilating the pupil and forcing the lazy eye to work. 

Written by: Healthplus24 team
Date last updated: August 11, 2013