What are the causes of amblyopia? There are many causes of amblyopia, including pediatric strabismus, high hyperopia, myopia and astigmatism, congenital cataracts, severe ptosis, and congenital hypoplasia of the optic center and optic nerve. There are also many ways to classify amblyopia, and depending on the cause amblyopia can be divided into: Strabismic amblyopia: Patients with strabismus or previous strabismus with amblyopia, but without fundus abnormalities. It is believed that this is because strabismus causes diplopia and visual disturbances that make the patient feel extremely uncomfortable, and the visual cortex of the brain actively inhibits the visual impulses transmitted from the macula of the strabismus, and the macular function of the eye is suppressed for a long time, resulting in amblyopia. This is the reason why Toto’s children suffer from amblyopia as we mentioned earlier. This kind of amblyopia is a consequence of strabismus, which is secondary and functional and therefore reversible, and the prognosis is good. Occasionally, however, a few primary cases do not improve significantly even with aggressive treatment. Refractive parallax amblyopia: due to the unequal clarity of the image formed in the macula of both eyes, even if the refractive error is corrected, the size of the image caused by refractive parallax is still unequal, resulting in the image of both eyes not easily or not fused into one, the visual cortical center can only inhibit the image of the eye with refractive error, so amblyopia occurs over time, this type of amblyopia is also functional, and therefore reversible. Clinically, we observe that a difference of 150 degrees in binocular hyperopia or 100 degrees in astigmatism can lead to refractive amblyopia. Formal deprivation amblyopia: In infancy, due to corneal clouding, congenital cataract, or ptosis blocking the pupil, the light stimulus cannot fully enter the eye, depriving the macula of the opportunity to receive normal light stimulation, resulting in functional impairment and amblyopia. Congenital amblyopia: The pathogenesis is not well understood, and Von Noorden speculates that newborns often have retinal or optic pathway hemorrhage, which may affect the normal development of visual function. Some congenital amblyopia is secondary to nystagmus. Refractive amblyopia: Mostly bilateral, it occurs in patients with high refractive error who have not worn corrective lenses and have equal or similar visual acuity in both eyes; refractive amblyopia is most often seen in people with hyperopic refractive error. This type of amblyopia has similar binocular vision and no binocular image fusion disorder, so it does not cause macular function inhibition, so after wearing suitable corrective glasses, vision can be gradually improved without special treatment, but it takes a long time. On the surface, the above five types of amblyopia are all amblyopia, but there are essential differences in the pathogenesis. Strabismus and refractive amblyopia have the same light stimulation into both eyes, and the macula of both eyes are involved in the development of visual function, so the prognosis is better. However, form-deprived amblyopia is a condition in which the visual function has not yet developed to a perfect or mature stage during infancy and childhood, and the retina does not receive enough light stimulation to fully participate in the development of visual function, resulting in amblyopia, which not only has low vision but also has a poor prognosis. The consequences of monocular disorders are more serious than those of binoculars. Therefore, special care should be taken when covering the eyes of infants and children due to eye disease to avoid the formation of deprivation amblyopia (especially in children under 6 months of age). The prognosis for congenital and form-deprived amblyopia is poor. Refractive, strabismic and refractive amblyopia have a better prognosis, and the key is early detection, timely and correct treatment, and most of them can improve their visual acuity and have a good chance of obtaining normal vision.