Amblyopia is generally divided into many types according to the causes, mainly tangible deprivation amblyopia, strabismus amblyopia, ametropic amblyopia and anisometropic amblyopia. Amblyopia is also divided into central fixation amblyopia and eccentric amblyopia according to the nature of fixation. The determination of the nature of fixation is of great significance for the selection of amblyopia training methods and the evaluation of prognosis.

Form deprivation amblyopia

Form deprivation amblyopia is often congenital or early acquired. Various factors lead to insufficient light stimulation into the eyeball, depriving the macula of the opportunity to receive normal light stimulation, resulting in visual impairment and amblyopia. For example, in infancy, due to the opacity of refractive stroma (congenital or traumatic cataract, corneal scar, etc.), complete blepharoptosis, improper mask covering, etc., which limits the full input of visual perception and interferes with the normal development of vision, amblyopia will occur. For example, the right eye is a cataract, so that external objects cannot be clearly imaged on the retina, and the effective stimulation of light on the retina is not enough, resulting in low vision in the right eye.

In recent years, relevant scholars have used animal models to study the pathogenesis of amblyopia and found that in the process of visual development of animals, there is a stage that is particularly sensitive to external stimuli, which is called the sensitive period. It is particularly sensitive in the early stage of the sensitive period, which is the most prone to form deprivation amblyopia.

The time required for the formation of form deprivation amblyopia is shorter than that for the formation of strabismus amblyopia, ametropic amblyopia and other types of amblyopia. Infants may form deprivation amblyopia even if they cover their monocles briefly. Some studies have shown that 7 days of inappropriate monocular covering can form irreversible amblyopia. Therefore, in the critical period of visual development, avoid inappropriate monocular covering, especially infants within 6 months. If necessary, they can cover their eyes alternately. The possibility of amblyopia caused by covering after 2 to 3 years old is small. Even if amblyopia occurs, the treatment is relatively easy to succeed.

Form deprivation amblyopia can be unilateral or bilateral. Unilateral is more serious, often accompanied by secondary esotropia or exotropia. Unilateral form deprivation amblyopia is mainly caused by visual deprivation and abnormal binocular interaction. On the contrary, if the clarity of binocular images is also reduced, the competition between binocular images does not exist, so only visual deprivation is a factor that produces amblyopia.