Amblyopia Or Lazy Eye

What is Amblyopia?

Amblyopia is commonly referred to as ‘lazy eye’. It is an abnormal visual development that causes poor vision.

Lazy eyes can affect only one eye, in which case the child depends solely on a good eye for vision. Sometimes both eyes are affected.

Amblyopia affects a patient's visual acuity, how clearly you can see.

Who Is Affected by Amblyopia or Lazy Eye

Amblyopia is present in infancy and the early stages of childhood. An average of 2% of the population in developed countries suffer from amblyopia. If left untreated reduced vision will be lifelong.

Causes Of Amblyopia or Lazy Eye

Amblyopia is caused when the nerves carrying information from the eye to the brain are impaired. Nerve pathway impairment can be caused due to eye problems, including:

• Strabismic Amblyopia (crossed eye) develops when one eye turns in, out, up or down as opposed to the healthy eye
• Deprivation Amblyopia develops due to cataracts (clouding of the eye's lens) or other eye problems that deprive the visual experience
• Refractive Amblyopia develops due to larger or unequal refractive error (inability of the eye's lens to focus, leading to short-sightedness or long-sightedness)

When the brain receives a blurred image or the wrong image from the defective eye, it gets confused, and over time, favours only the healthy eye. It ignores signals from the weaker eye, leading to poor vision.

Symptoms of Amblyopia or Lazy Eye

The symptoms of Amblyopia or ‘lazy eye’ include:

As others observe

• Visibly misaligned eyes outwards, upwards, downwards or at an angle
• A cross-eyed appearance of the eyes, esotropia
• Eyes that periodically wander out, wall-eyed or exotropia
• A upward misalignment is hypertropia
• A downward misalignment is hyoptropia
• Eyes that do not work in coordination

As a patient observes

• Poor depth perception
• Poor vision in the misaligned eye
• Blurred vision in the affected eye
• Double vision in childhood (strabismus)
• Disturbance in toddlers and babies when covering the good eye
• Inability to focus the eye

How is Amblyopia or Lazy Eye Diagnosed?

Because Amblyopia affects children in infancy and in their toddler years, an assessment must be performed before they are old enough to start school. Early diagnosis and treatment improve the chances of complete recovery.

Assessment to determine the presence of Amblyopia include:

Eye Test

A specialist eye assessment is a comprehensive eye examination to detect not only a lazy eye (Amblyopia) and a wandering eye but for other eye or vision pathology, including:

• differences in vision
• the poor vision in one or both eyes
• tumours
• Inflammation
• and other pathology

Some tests conducted will depend on your child’s age.

Age Specific Diagnosis

An eye exam completed at six months and again at three years can help detect Amblyopia before it becomes prominent.

If there is a genetic component, you must consult with an eye care specialist at the earliest stages to help your child receive the appropriate treatment to minimise the impact of Amblyopia.

• For Newborns, a ‘red reflex test’ is conducted using a lighted magnifying device (ophthalmoscope) to check for cataracts and visual reaction to light
• For Infants, the test will check for the ability to fix and follow a moving object and test for the presence of strabismus.
• For Toddlers, a pupillary red reflex test and an assessment of alignment and vision will be performed using toys.
• For Pre-schoolers and older children, the Orthoptist will use pictures or letters to test each eye in turn by patching the other eye and perform a detail assessment of alignment.

How is Amblyopia or Lazy Eye Treated?

Treatment involves targeting the weak eye and encouraging children to use the weaker eye frequently. The affected eye is examined for common conditions, including astigmatism, and the eye is treated with the appropriate prescription lenses if required.

Amblyopia is then further addressed by wearing a patch. A patch is recommended for children to wear over the good eye. The healthy eye is covered with a patch, encouraging the use of the weaker eye. Although challenging, over time, the weaker eye becomes stronger. It can take weeks to months to improve visual acuity in the weaker eye.

Treatment for lazy eye begins in early childhood, and therapy options will depend on the cause and degree of the lazy eye affecting your child’s vision.

Conservative Treatment

Corrective Eyewear:

Your Ophthalmologist may suggest eyeglasses or contact lenses for a lazy eye that is caused due to

• near-sightedness (close objects are apparent, but distant objects appear blurred)
• farsightedness (distant objects are apparent, but close objects appear blurred)
• astigmatism (blurred vision due to an irregular curvature of the eye’s lens)

Spectacles or contact lenses may be all your child needs to correct a lazy eye.

Eye Patches

An eye patch is used to cover the stronger eye so that the weaker eye is stimulated. An eye patch can be used for 2 hours per day or longer if required.

This therapy helps the part of the brain that controls vision to develop completely.

Eye Drops

Eye drops are an alternative to patches and are instilled on average twice-weekly into the stronger eye to temporarily blur vision and encourage the patient to use the weaker eye.

Your doctor may suggest other active therapies like puzzles, drawing, or computer games in addition to eye patches or eye drops.

Surgery:

Your doctor will recommend surgical repair of the eye muscles if the eyes are crossed or wander apart. Surgery will also be required to correct drooping eyelids or cataracts.

Improvement of vision in lazy eye patients may take several weeks to months. Better results and visual improvements are seen if the treatment for lazy eye beings early during childhood.

Treatment may take longer or be less effective if a lazy eye is not diagnosed until the pre-teen, teen or adult years.

What If Amblyopia or Lazy Eye Is Untreated

If Amblyopia is left untreated by failing to wear a patch, the affected eye will continue to weaken, and vision will deteriorate over time. Amblyopia can cause mild to a severe, permanent loss of vision.

For children who begin to experience weak visual acuity in the affected eye after ceasing wearing the patch, the patch may have to be reapplied.