What is the reason for the decrease in vision after wearing glasses to cover amblyopia?

Patient's question:

My son has amblyopia in his left eye. After wearing a patch for two months, his uncorrected vision dropped from 0.4 to 0.1. Why is this?
First follow-up question: The glasses were prescribed by an ophthalmology hospital, and the corrected vision reached 0.5+. According to the doctor's guidance, he wore the patch for six days a week and took one day off. After a month, the corrected vision improved to 0.6-, but his uncorrected vision declined from 0.4 to 0.1. The doctor said to only focus on the corrected vision. Should I continue wearing the patch for training, and can his uncorrected vision still improve?

Doctor's answer:

Hello: Myth 1 about Amblyopia Treatment
Many parents believe that amblyopia should be treated only after the child starts school, when they are more mature and easier to cooperate with the treatment. However, this is incorrect. Amblyopia treatment is closely related to age. Some studies indicate that the first year of life is a critical period, and before the age of 8 is a sensitive period. After the age of 14, the effectiveness of treatment becomes questionable. After adulthood, treatment is almost ineffective.
Myth 2 about Amblyopia Treatment
If a child has poor vision, it must be myopia.
Amblyopia is fundamentally a different condition from myopia. Myopia is caused by excessive tension in the eye's accommodative muscles (ciliary muscles) or genetic reasons, leading to an elongated eyeball, resulting in blurred distance vision and clear near vision. Wearing glasses can often restore normal vision. In contrast, amblyopia is a disorder of delayed or disordered visual function development, often accompanied by strabismus or high refractive errors. Even with glasses, the vision cannot be corrected to normal levels. The two conditions are essentially different.
The harm of amblyopia to a child's visual function is much greater than that of myopia. Because myopia is merely a decline in distance vision without other visual function impairments, vision correction is not limited by age. In contrast, children with amblyopia not only have poor vision that cannot be corrected but also lack binocular single vision function and stereopsis. This will prevent them from performing tasks such as driving, surveying, and fine work in the future. It not only affects their career prospects but also directly impacts the quality of the population in our country.
Myth 3 about Amblyopia Treatment
Simply wearing glasses can treat amblyopia.
Simply wearing glasses cannot treat amblyopia. When there is refractive error, glasses are indeed necessary, but what is more important is amblyopia training.