1. What is Strabismic Amblyopia or Lazy Eye?
Amblyopia or lazy eye is reduced vision in eye in the absence of anatomical defects. As a result, the eyes do not receive equal images, leading the visual system to adapt to this change. One of the causes of lazy eye can be strabismus or squint which causes amblyopia due to not using the strabismic eye and loss of binocular vision. Strabismus is a deviation of one eye with loss of eye parallelism. To avoid double vision caused by poorly aligned eyes, the brain ignores the visual input from the misaligned eye, leading to amblyopia in that eye. This type of amblyopia is called strabismic amblyopia.
2. What happens when someone experiences the condition?
When someone experiences this condition, they have squint in one or both eyes, loss of binocular vision and reduced vision which may affect daily activities. Strabismic amblyopia is characterized by a distorted spatial perception. The condition is an alteration of the visual cortex function which is due to suppression and deprivation of one of the eyes, leading to unilateral visual deterioration. The brain receives two images with different spatial projection, one of them coming from the eye with the squint. As a result, the brain cannot create a combination of images from both eyes to generate a stereoscopic vision.
3. Why is it common in children? Can it happen in any age?
The condition is common in children as squint in childhood can affect our vision more. Our visual components including binocular vision are under the development process till six years of age. So any squint related issues up till this age, will affect visual development and lead to moderate to severe amblyopia. When the visual system is completely formed, the perception of non-corresponding images by the two eyes leads to double vision, but when the visual system is in its critical period of development, the brain is still capable of using mechanisms to avoid diplopia by inhibiting the activation of the retino cortical pathways originating from the fovea of the deviating eye. However, this can happen at any age, as squint for long term can lead to the non-usage of the eye and amblyopia.
4. What are the signs and symptoms for this?
People with Strabismic Amblyopia will often experience:
- Reduced vision in one or both eyes
- Alteration or poor depth perception
- Squinting or deviation of the eyes
- Abnormal head posture or tilting
- Difficulty catching and throwing objects
- Eye strain or fatigue with near work
It is important to note that a young child with amblyopia may rarely express any symptoms or knows that whatever they are experiencing is not normal.
5. How can the condition be treated or corrected?
Early detection and timely treatment offers the best outcome for Strabismic Amblyopia. The treatment may include vision therapy, eye patching, eye drops, strabismus surgery or commonly known as squint eye surgery to straighten the eyes, use of prescription lenses or a combination of those options. Squint correction is necessary especially before six years of age to restore ocular alignment and binocular vision. Beyond that, even though vision can be improved to different degrees with amblyopia therapy, binocular vision cannot be restored. Hence, children experiencing any symptoms should be checked for squint and amblyopia. It is important that children are taken to paediatric eye specialist, optometrist or ophthalmologist for a comprehensive visual assessment to help catch problems like amblyopia at an early stage.
6. What are the precautions one needs to take?
- Regular eye checkup and comprehensive visual assessment for vision and evidence of squint
- Do not neglect symptoms of low vision, abnormal head posture or deviation of eyes especially in children
- Consult with a paediatric eye specialist for complete checkup and treatment options in case of squint
- Plan a definitive correction as advised by your squint specialist before six years of age in children and at the earliest in adults
- Educate parents and family members about Strabismic Amblyopia and to identify the potential signs of danger
Dr. Sri Ganesh, Chairman and Managing Director, Nethradhama Super Speciality Eye Hospital, Bangalore