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What is Amblyopia?

Amblyopia, commonly known as lazy eye, is the condition noted by reduced vision developed when the brain does not fully acknowledge the images seen by the amblyopic eye. This almost always affects only one eye but may manifest with reduction of vision in both eyes. In Hong Kong, it is estimated that 2% to 4% of children under six have some form of amblyopia. Generally speaking, children’s vision between the age of 4 and 5 is similar to adults, as their eyes have developed to structural maturity. However, once the eyes fail to provide a clear image to the brain during visual development, the lack of stimulation causes the brain to be under-stimulated and stays at a low level resulting in amblyopia.

Amblyopia is one of the leading causes of decreased vision among children. The good news is that early diagnosis and treatment before the age of 8 can usually prevent long-term vision problems. Untreated lazy eye(s) can cause permanent loss of vision in the affected eye(s).


It is difficult for children to vocalize their amblyopia condition, partly as they may have become accustomed to using the dominant eye. Behaviors may evolve such as looking objects with an abnormal head posture (face turn, head tilt), squinting or objecting to occlusion of their dominant eye.

If in doubt, it is advisable to bring your child for an eye examination as soon as possible. Timing is key. The opportunity for treating amblyopia before the age of 8 is much better; the younger your child the higher the chance of success in visual correction.

Case Scenario

Isaac, a 4-year-old boy, was noted by his parents to have messy handwriting and no interest in reading. Doing homework was a nightmare for the whole family. He would scribble all over his workbook, driving his parents mad. At first, his parents were worried about his lack of focus and poor learning attitude. After Isaac’s repeated “I can’t see at all” complaints while doing homework, his parents decided to bring him to the ophthalmologist. After a comprehensive examination, the doctor diagnosed amblyopia in both of his eyes. Isaac’s vision had affected his ability and interest in learning and reading.

With professional support and treatment, the parents and medical staff could now work together to help Isaac. Isaac started wearing spectacles to correct his prescription. A few months later, he started patching exercises for both eyes, alternating left and right on alternate days.

After 6 months, Isaac’s vision improved significantly and he was able to properly complete his homework to his parents’ delight. This effect is expected to persist to adulthood.


The difference between amblyopia and ordinary shortsighted / longsighted is that amblyopia cannot be remedied by spectacles immediately. Luckily with appropriate visual rehabilitation, vision can be optimized and commonly revert back to normal range. 

If amblyopia is diagnosed, the treatment plan needs to be determined according to the patient’s situation. In general, spectacles should first be worn to adjust the prescription, followed by patching exercises to train the less dominant eye. Patching may show an improvement in as short as a few months.

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