Common internal strabismus refers to the separation of the visual axes of both eyes and the absence of quality lesions of the extraocular muscles and their innervation, and the degree of deviation is equal in all directions, regardless of which eye is the focusing eye. Insufficient strength or paralysis of the extraocular muscles is the main cause of non-common strabismus. Other causes are abnormal innervation of the extraocular muscles, such as retrobulbar syndrome, and A-V sign. Primary common internal strabismus is divided into two main categories: regulated and non-regulated. Regulated internal strabismus is divided into refractive and high A. When strabismus is present (1) children with regulated common internal strabismus are hyperopic due to frequent over-adjustment and excessive convergence. Due to the underdevelopment of fusion function, it is easy to produce internal strabismus. This is known as moderated common internal strabismus, which mostly appears around 3 years old. If children with strabismus are corrected with dilated lenses at an early stage, they can correct eye position abnormalities, correct hyperopia, and eliminate regulatory strabismus. At the same time, it can improve visual acuity, strengthen the fixation reflex and integration ability, establish and consolidate binocular monovision, and also prevent amblyopia. Otherwise, if the strabismus is prolonged, the eye with better visual acuity is often used without the other eye, resulting in the formation of secondary strabismic amblyopia in the child’s strabismus and the loss of binocular monocularity, it is difficult to get a functional cure. Patients with common internal strabismus need to have their pupils dilated for photometry. Atropine 1% is applied to both eyes once a night for 7 days. After pupil dilatation, the fundus is checked at the same time to observe the type of fixation and to perform amblyopia examination. If hyperopia is confirmed by the photometry, regardless of the occurrence of amblyopia, full correction lenses must be worn immediately (the so-called “full correction” is obtained by subtracting +1.OOD from the spherical lens value in the refractive power of the eye from the photometry, preserving the ciliary muscle tension. If the right eye is wearing +7.00Ds=1.O for a 1m examination, minus the correction of the examination distance, the refraction of the eye is +6.ODs, and the full correction lens is 10.00DS). If necessary, an overcorrection is performed (in the above example, the overcorrected lens is +6.00Ds) to see if the eye can be brought into proper alignment. The child will feel blurred and uncomfortable wearing these highly hyperopic lenses. A pupil dilator can be ordered to paralyze the ciliary muscle. This way, wearing the lenses is easily accepted. After three months, an outpatient review will be conducted to observe the change in eye position. If the deviation is corrected after wearing the lenses and the eye position is ortho, it means that it is an adjusted strabismus. At this point, the overcorrected glasses should be replaced, and the glasses should be reopened and refitted with a lower prescription that does not result in a skewed eye position. Wear the glasses again for 6 months to review. If appropriate, gradually reduce the prescription. Regarding the appropriateness of reducing the prescription, we can use the masking method to see if the eye position is skewed again. If the oblique position appears again or disrupts the monocularity of both eyes, it means that the reduction of the lens is inappropriate and should be corrected or reduced slowly. In short, the principle is to gradually reduce the farsightedness of the lenses without affecting the eye position. However, children with full or overcorrected glasses should not wear them for too long. As children develop, the anterior-posterior axis of the eye grows slowly and the cornea and lens become flat, so the degree of hyperopia gradually decreases. If you wear these glasses for a long time, will make its physiological farsightedness reduction is obstructed; at the same time, because of long-term adjustment, according to the principle of near reflex, adjustment and convergence have a close relationship between the long-term adjustment to the secondary convergence function is insufficient, and over time caused by exotropia. If the eye position is not deviated after wearing the lens, but there is a mild internal obliquity when looking at the near, the internal obliquity can be corrected if a certain positive lens is added. This means that the child’s vergence response is too strong, and the adjustment causes a high Ac/A value, which means that the vergence is too strong and the adjustment is not coordinated with the adjustment. In this case, bifocal glasses and pupil reduction agents can be used to assist in the treatment. Bifocal glasses should be used ranklin split bifocal glasses, the upper and lower halves of the two luminosity boundary is straight, the lower half of the near with the lens part must be large, should be as high as the lower edge of the pupil, so that the child still from the upper lens to see near objects, affecting the treatment effect. Wearing these glasses increases the ortho-lens degree due to the near vision, reduces the regulatory convergence, promotes the fusion of the image, and can make the internal obliquity eliminated. The use of pupil reducing agents, such as 1% Mao Guo Yun Xiang Alkaline solution, can stimulate the ciliary muscle tension, reducing the central nerve regulation, so that the regulatory convergence is reduced. In addition, the drug makes the pupil narrow, so the near object clear, in reducing the use of regulation at the same time, convergence is also reduced. As mentioned above, bifocal spectacles and pupil reduction agents are effective for the convergence-excessive type of moderated internal strabismus. If the degree of internal strabismus is reduced after wearing glasses, but there is still obliquity, or if the eye position does not appear oblique when looking at distance but oblique when looking at near, and there is still obliquity after looking at near and using corrective glasses, then it means that it is partially adjusted internal strabismus, that is, the part of its strabismus adjustment factor cannot be corrected by wearing glasses, and other treatment methods, such as surgery, are needed. If the child has amblyopia, amblyopia should be treated, and then strabismus surgery should be performed after the vision of both eyes is balanced, and then lenses should be prescribed according to the refractive state to improve the vision after surgery. If the review after 3 months of wearing glasses shows that the strabismus is not controlled at all, it is proved to be non-adjusted strabismus and other treatment methods, such as surgery, should be used. After surgery, the prescription will be based on the refractive status, and then the main focus will be on improving visual acuity.