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July 23, 2024
Amblyopia, or lazy eye, is a condition where one eye has poor vision despite using glasses or contacts. It starts in childhood and can cause permanent vision loss if not treated, but early detection and treatment can greatly improve outcomes.
Amblyopia occurs when the brain and eye don’t work together, causing the brain to ignore the signals from one eye. This is typically due to one eye being stronger than the other, leading to the weaker eye deteriorating over time.
With time, the brain starts to rely more and more on the stronger eye, which results in the weaker eye getting worse.
As the stronger eye works better, amblyopia is commonly known as ‘lazy eye’. However, it’s important to remember that people with amblyopia are not lazy, they have no control over how their eyes work.
This condition usually starts in childhood and is one of the most common causes of vision loss in children. Fortunately, early treatment can work well and help in preventing long-term vision issues.
Amblyopia usually occurs when one eye is stronger, causing the weaker eye to worsen over time. It can be caused by various conditions.
Strabismus is a common cause of amblyopia where misaligned eyes lead to double vision, causing the brain to ignore one eye and potentially develop amblyopia.
Types of strabismus include esotropia, exotropia, hypertropia, and hypotropia.
Anisometropia, or differences in refractive errors between the eyes, can lead to amblyopia when one eye has significantly worse vision than the other. The brain will favour the eye with clearer vision, causing the weaker eye to become lazy.
Even without a noticeable misalignment, anisometropic amblyopia can occur if the brain consistently favours one eye over the other to focus better.
This occurs when there is an obstruction in the visual pathway during early childhood, such as congenital cataracts, ptosis (drooping eyelid), corneal opacities, or any condition that prevents light from entering the eye and focusing on the retina.
Deprivation amblyopia can also result from prolonged patching of one eye for other eye conditions, such as treating a corneal ulcer or post-surgical recovery.
What are the risk factors that can lead to the condition? Who’s at risk of developing it?
A family history of amblyopia, strabismus, or significant refractive errors increases the risk of children developing amblyopia. Genetic predispositions play a significant role in eye alignment and focusing ability.
Children born prematurely or with low birth weight are at higher risk for developmental issues, including vision problems like amblyopia. Retinopathy of prematurity (ROP), a condition affecting premature infants, can lead to retinal damage and subsequent amblyopia.
Children with developmental delays or neurological conditions such as cerebral palsy, down syndrome, or other genetic syndromes are more prone to amblyopia due to higher incidences of associated vision problems.
Delayed correction of significant refractive errors can increase the risk of amblyopia. Regular eye exams, especially in early childhood, are crucial for detecting and correcting refractive errors.
Trauma to the eye, leading to conditions such as corneal scars, lens dislocation, or retinal damage, can obstruct normal vision and result in amblyopia if not promptly treated.
Certain medical conditions, such as ptosis (drooping eyelid), cataracts, or retinal diseases, can impede clear vision and contribute to the development of amblyopia.
Early detection of amblyopia and its risk factors is vital for effective treatment and prevention of long-term visual impairment. Regular paediatric eye examinations are recommended, especially where any of the risk factors are present.
Vision screenings should start at birth and continue at regular intervals throughout early childhood.
Parents and caregivers should be vigilant for signs of amblyopia, especially if there is a family history of the condition or other eye problems. Some signs to look out for include:
Routine vision screenings during paediatric check-ups are vital. Early detection through these screenings can identify children at risk for amblyopia, allowing for timely intervention.
Diagnosing amblyopia involves a comprehensive eye examination by an eye care professional, usually a paediatric ophthalmologist or optometrist. The diagnosis aims to identify the reduced visual acuity in one eye and determine the underlying cause. Here are the key steps in diagnosing amblyopia:
The eye care professional will inquire about the child’s overall health, developmental milestones, and any previous eye conditions or treatments. Information about any family history of amblyopia, strabismus, or significant refractive errors is gathered, as these can be risk factors.
Visual acuity is tested using methods suitable for the child’s age and developmental level. For infants and very young children, preferential-looking techniques or visual evoked potential (VEP) tests may be used. For toddlers and preschoolers, picture charts (such as LEA symbols or Allen figures) are used to assess visual acuity. Older children who can recognize letters are tested using standard eye charts (such as the Snellen chart).
Two types of refraction tests are done in two ways
Usually, two types of ocular alignment tests are done:
Binocular function tests are also done in two ways:
Treatment for amblyopia is most effective when started early, ideally before the age of 7. The goal of treatment is to force the brain to use the weaker eye, thereby improving vision. Treatment options include:
If refractive errors are the cause of amblyopia, prescribing glasses or contact lenses can correct the unequal focusing problem. For some children, wearing glasses alone can improve vision in the amblyopic eye.
Patching is one of the most common and effective treatments for amblyopia. It involves placing a patch over the stronger eye for several hours a day to force the brain to use the weaker eye. The duration of patching can vary based on the severity of amblyopia and the age of the child.
Atropine eye drops can be used to blur the vision in the stronger eye, encouraging the use of the amblyopic eye. This method can be as effective as patching and is often more acceptable to children who resist wearing an eye patch.
Vision therapy involves a series of exercises designed to improve the visual abilities of the amblyopic eye. These exercises can be performed in an eye care professional’s office and supplemented with at-home activities. Vision therapy can address issues like eye tracking, focusing, and coordination.
In some cases, surgery may be required to correct the underlying cause of amblyopia, such as strabismus or cataracts. While surgery alone does not treat amblyopia, it can improve the alignment or remove obstructions, making other treatments more effective.
Parents and caregivers play a crucial role in the successful treatment of amblyopia. Consistency and adherence to the prescribed treatment plan are essential for improvement. Here are some strategies to help:
With early and effective treatment, many children with amblyopia can achieve significant improvement in vision. However, some degree of visual impairment may persist, especially in cases where treatment is delayed. Regular follow-up care is crucial to ensure that the improvements are maintained and to address any recurrence of the condition.
However, there are some challenges and considerations with regard to the treatment and recovery:
The younger the child, the better the prognosis for treatment. However, treatment can still be effective in older children and even teenagers. So start early.
Adherence to the treatment regimen is critical. Inconsistent treatment can lead to suboptimal outcomes.
Wearing an eye patch or glasses can be challenging for children. Support from parents, caregivers, and teachers is essential to help them cope with any social or emotional issues.
Research in the field of amblyopia is ongoing, with promising advances aimed at improving outcomes and making treatment more effective and less burdensome for children and families. Some of these advances include:
Emerging technologies such as virtual reality (VR) and video games designed specifically for vision therapy are being explored. These interactive therapies can make treatment more engaging for children and have shown promise in clinical studies.
New pharmacological treatments are being investigated to enhance the plasticity of the brain and improve the effectiveness of traditional therapies. These approaches aim to make the brain more receptive to visual inputs from the amblyopic eye.
Understanding the genetic basis of amblyopia can lead to more personalised treatment strategies. Identifying specific genetic markers associated with amblyopia can help predict which children are at higher risk and tailor interventions accordingly.
Increasing awareness and accessibility to vision screenings and eye care services is crucial. Public health initiatives aimed at early detection and intervention can significantly reduce the prevalence of amblyopia and its long-term impact on children’s lives.
Amblyopia is a common but treatable condition that can have a profound impact on a child’s visual development and quality of life. Early detection through routine vision screenings, followed by prompt and consistent treatment, is essential for improving visual outcomes. With the dedication of parents, caregivers, and eye care professionals, children with amblyopia can achieve their full visual potential.
The future of amblyopia treatment is promising, with ongoing research and technological advancements offering new hope for even better outcomes. By continuing to prioritise early detection and innovative treatment approaches, we can ensure that all children have the opportunity to enjoy a lifetime of healthy vision.
Yes, lazy eye can be corrected with early detection and appropriate treatment.
Amblyopia can be considered a disability if it significantly impairs vision and affects daily activities.
Yes, amblyopia can often be cured if treated early and consistently during childhood.
Dr Nor Akmal Bahari
Consultant Paediatric Ophthalmologist (Visiting)
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