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Amblyopia (Lazy Eye) – Causes, Symptoms, Diagnosis, Treatment & Prevention

What is Amblyopia?

Amblyopia, sometimes known as “lazy eye”, is when there is reduced vision (usually in one eye) due to abnormal visual development in early childhood. When the weaker eye transmits less signal, the brain focuses its efforts more on the better seeing eye. This results in the vision of the one eye much weaker (“lazy”), while the other eye works better. Amblyopia begins in young children (from birth up to age ten years), and if it is untreated, can last a lifetime. Amblyopia is relatively common, affecting 2 – 3% of the population.

Symptoms and Signs of Amblyopia

Amblyopia is quite difficult to notice without a detailed eye examination. Some symptoms and signs include:

  1. The eye wanders inward or outward
  2. Trouble with depth perception
  3. Blurred vision in one eye

If untreated, the child will have poor vision in the weaker eye for the rest of their life. This can affect the ability to get a driving license, and choice of occupation.

Causes of Amblyopia

Visual development occurs during from birth and progresses in first few years of life. At birth, neonates have poor vision. As vision centres in the brain develop, the vision improves rapidly in the first few weeks and months of life. Anything affecting normal vision leads to the brain pathways not developing properly. Causes includes:

Refractive errors

These are common issues, where the eye(s) cannot focus properly, leading to Refractive Amblyopia. There are different types of refractive errors. Myopia (Nearsightedness) – close objects are clear while far objects are blurry, Hypermetropia (Farsightedness) – far objects are clear while near objects are blurry, and Astigmatism – blurred vision at all distances due to asymmetric curvature of the cornea. A focusing issue can usually be treated with glasses or contact lenses, however if ignored, they can cause the brain to permanently depend on one eye only.

Strabismus (crossed eyes)

Strabismus is when the two eyes are not aligned with each other (one eye position is different to the other). This can lead to amblyopia, as the brain may start to ignore the eye that is turned more often.

Deprivation

Deprivation amblyopia occurs when there is an obstruction to light entering the eye, such as clouding of the lens (cataract) or droopy eyelid (ptosis). Deprivation amblyopia is one of the serious types of amblyopia which requires urgent attention even in early infancy. If not treated at the right time, deprivation can lead to permanent blindness. In some cases, deprivation amblyopia can affect both eyes.

Amblyopia Risk Factors

Factors that pose a high risk for Amblyopia in children include:

  1. Premature birth
  2. History of Amblyopia or similar condition in the family
  3. Developmental disabilities

Consequences of untreated Amblyopia

If amblyopia left untreated, it can have several consequences:

  1. Reduced Visual Acuity: The most apparent consequence of untreated amblyopia is reduced visual acuity (clarity of vision) in the affected eye. The brain suppresses signals from the weaker eye, leading to poor development of visual pathways.
  2. Depth Perception Issues: Amblyopia can affect depth perception, making it challenging for individuals to accurately judge distances and perceive the three-dimensional aspects of the environment. This can impact activities that require good depth perception, such as sports or driving.
  3. Strabismus (Misalignment of the Eyes): Amblyopia is often associated with strabismus, a condition where the eyes do not align properly. The brain may suppress signals from one eye to avoid double vision caused by misalignment.
  4. Difficulty with Fine Motor Skills: Reduced visual acuity and depth perception can affect fine motor skills, especially tasks that require hand-eye coordination. This may impact activities such as writing, drawing, or other precision tasks.
  5. Impaired Educational and Social Development: Children with untreated amblyopia may face challenges in the classroom, as visual impairment can affect their ability to read, write, and participate in visual learning activities. Social development may also be impacted due to self-consciousness about the appearance of misaligned eyes.
  6. Reduced Quality of Life: Untreated amblyopia can have a long-term impact on an individual’s quality of life. Limited visual capabilities may affect employment opportunities, recreational activities, and overall well-being.

It is crucial to detect and treat amblyopia early to maximise the chances of successful intervention.

Diagnosis

Diagnosis of Amblyopia usually involves an eye professional testing visual function in detail. It is important to cover one eye and then the other, to test vision in each eye separately. In Australia, most children have a “screening” vision check in the community before they start school. In NSW, it is known as the StEPS program (Statewide Eyesight Preschooler Screening Program). This is so that any child with amblyopia can be picked up and treatment given while the visual pathways are still developing. A complete eye examination will help find out if there are any other problems.

Treatment

It is important to start amblyopia treatment as early as possible. Early intervention leads to better visual outcomes. The treatment prescribed depends on the cause and severity of amblyopia. Treatments include:

Glasses/contact lenses

This is the most common method for treating Refractive Amblyopia. Children are to wear the required glasses / contact lenses for the prescribed period with regular eye check-ups. This helps to determine the improvements in vision and to make necessary adjustments. Moreover, glasses can sometimes also help in correcting eye turn (accommodative esotropia). For mild cases of Amblyopia, glasses wear alone can cure the problem.

Eye patch (occlusion treatment)

Eye patches are used to cover the stronger eye for a certain number of hours every day. This forces the brain to communicate with the weaker eye, and improve its function. It should be used according to the directions of the eye doctor. The patch can be work directly on the skin, or placed over glasses (less effective). Patching treatment is usually weaned after months to years, when the vision has equalised, or the maximum benefit has been reached. 

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Bangerter filter

These are translucent filtersthat are worn over the glasses to create a blur of the image seen from the stronger eye.

Eye drops

Atropine is a medication used to temporarily blur vision in the stronger eye. It dilates the pupil and paralyses the focusing ability, creating a blur effect when looking at objects. These are recommended to be used on weekends or weekdays according to the requirement. This is an alternative to eye patches, but is not as strong as the vision from the stronger eye is not completely blocked.

Surgery

It is rare to perform surgery for Amblyopia, but if conditions like cataracts or droopy eyelids block the light from entering the eye, then surgery is necessary. In certain cases of Strabismus, eye muscle surgery may help to re-align the eyes and assist to some degree with amblyopia management.

Prevention

There are no preventive measures for Amblyopia. Early detection and treatment is helpful. Parents are encouraged to seek a detailed eye examination with an ophthalmologist if they feel that their child is not seeing well out of one or both eyes.

FAQs

  1. Can you fix amblyopia with eye exercises?

    While eye exercises may help improve certain visual skills, they are not a standalone solution. Treatment often involves a combination of patching the stronger eye, using corrective lenses, and sometimes, eye exercises prescribed by an eye care professional.
  1. Can I prevent my child from developing amblyopia?

    Early detection and intervention are crucial in preventing amblyopia. Regular eye examinations for children can identify any issues promptly. If detected early, treatment options are more effective in preventing the development of amblyopia.
  1. Can my child grow out of amblyopia?

    Amblyopia is often more successfully treated during childhood. However, without intervention, the condition may persist into adulthood. Early diagnosis and appropriate treatment increase the likelihood of a successful outcome.
  2. Does amblyopia get worse with age?

    While amblyopia itself does not necessarily worsen with age, the effectiveness of treatment may decrease. It is important to address amblyopia early for the best possible outcome.
  1. Is there anything I can do to help my child with amblyopia at home?

    Complementing professional treatment, you can encourage your child to consistently wear any prescribed glasses or patches. Engaging in activities that stimulate both eyes, such as reading or playing games, may also be beneficial.
  1. Is this condition likely to recur after treatment?

    With appropriate and timely treatment, the recurrence of amblyopia is less likely. However, regular follow-up appointments with an eye care professional are essential to monitor progress and intervene if needed.
  2. Can people with amblyopia drive?

    In many cases, individuals with amblyopia can drive, especially if their vision meets the legal requirements for driving. However, it is essential for anyone with vision issues to consult with an eye care professional and adhere to local driving regulations.

Conclusion

Amblyopia is a vision disorder starting in childhood but lasting for a person’s whole life. It may be curable if diagnosed early enough.

Dr Parth Shah is an ophthalmologist in Canberra who is committed to providing excellent eye care to all of his patients. He implements modern research and technology in order to achieve better visual outcomes.

Author Bio

Dr Parth Shah is an experienced ophthalmologist in Canberra, specialising in cataract surgery. With extensive training and experience, he is renowned for his expertise in the field. Dr Shah is dedicated not only to performing successful surgeries but also to patient education. His compassionate approach, combined with technical proficiency, has earned him the trust and gratitude of countless patients. He is a true advocate for eye health and a trusted name in the Canberra ophthalmology community.