Amblyopia refers to the patients whose far vision caused by functional factors is less than or equal to 0.8 and can not be corrected. In the 1960s, Wiesel and Hubel studied the effects of monocular deprivation and artificial strabismus on the structure and function of the visual system. For the first time, the onset of amblyopia was located in the primary cortex (V1 region). The competitive inhibition mechanism of cortical afferent was proposed. According to the latest research, the essence of amblyopia is a binocular problem in structure, so it leads to the binocular treatment of amblyopia. Binocular therapy can improve the visual function of both eyes and monocular.
It has been shown that the binocular activity of neurons in the visual cortex of children with strabismus has been changed. Under normal circumstances, these neurons first receive the excitation input from the opposite side, and then receive the excitation input from the same side. Through the mutual reinforcement of bilateral excitation signals, the production of binocular vision can be ensured. In children with strabismus, on the contrary, neurons still maintain the excitatory input from both eyes, but gaze neutralizes the neural response of strabismus through inhibition. Therefore, binocular vision has been greatly damaged. For strabismus patients, surgical correction of eye position is a key step, which creates necessary conditions for the reconstruction and recovery of binocular visual function. Only by establishing a sound binocular visual function, can we truly achieve the goal of cure.
Press and paste prism is a common correction method for strabismus. It can project the object image of gaze on the fovea of macula through the object image displacement, obtain better visual stimulation and response, improve the correspondence of normal retina, eliminate inhibition, and promote the recovery of binocular visual function. In this study, the use of pasted prism solves the problem that the binocular visual axis is parallel or the visual field of children with large angle exotropia is overlapped. When pasted prism is placed in front of the eyes, because of the reflection of the face of the prism, the refraction of the bottom and the diffraction effect of the groove, the visual acuity of the eyes wearing pasted prism decreases somewhat, and the visual acuity declines more obviously with the increase of the degree [15] if pasted in the The dominant eye can also inhibit the formation of the dominant eye and play the role of covering membrane. David wrightd et al. [16] research shows that the effect of pressing prism on the reduction of normal vision is more obvious than that of amblyopia. Therefore, the healthy eyes or eyes with better vision of strabismus patients are pasted with prism to reduce vision, reduce vision imbalance of both eyes, overlap the vision of both eyes, stimulate the fovea of both eyes, and achieve two goals with one stone.
In recent years, visual scientists have reported the new progress of visual neuroscience, namely "vision perceptual learning". "Visual perceptual learning" treatment technology is to use the plasticity of the brain nervous system, through specific visual stimulation and visual learning, activate the visual signal pathway, correct and improve the signal processing ability of the brain nervous system, improve the visual function of both eyes and one eye, so as to achieve the purpose of treatment [8–13]. Sterkin et al. Conducted personalized perceptual training for pilots who just appeared presbyopia, and found that the visual function of pilots has been greatly improved, including static and dynamic visual acuity, stereopsis, space congestion, contrast sensitivity and contrast discrimination. In addition, the visual information processing speed of pilots has also been improved. Camilleri and Yan et al found that the application of perception training can improve the vision and visual function of patients with mild myopia. Bianca et al. Trained 45 4-9-year-old children with visual impairment through visual perception training, and found that their near vision improved greatly after training. However, there are few applied researches in this field in China, and there is no report on the treatment of exotropia combined with amblyopia at present. In this study, the inhibition, perceptual eye position, order stereopsis and other functions of children are qualitatively and quantitatively analyzed through the visual perception function examination, so as to find out the balance state of children's eyes, carry out targeted visual perception training, and use the interaction process of two eyes Strengthen the establishment of simultaneous visual function and disinhibition treatment, establish simultaneous and stereoscopic visual function, at the same time, use the tendency of exotropia of human eyes to do abduction training to gradually reduce the internal deviation, and finally let some patients cure the internal deviation without surgery. The establishment of stereopsis and amblyopia at the same time can improve the effect of exotropia surgery. Strabismus and amblyopia can be treated at the same time.