Esophoria is a tendency for the eye position to deviate inward. Normally, it can be controlled by corrective fusion reflexes, preventing the appearance of strabismus and maintaining binocular single vision. Generally, symptoms may occur if esophoria exceeds 9^△, but this also depends on the patient's fusion function.

bubble_chart Etiology

1. Excessive convergence excitation of centrality.

2. The medial rectus muscle is stronger or has a more anterior insertion point, while the lateral rectus muscle is weaker or has a more posterior insertion point, with abnormalities in the check ligaments and intermuscular membrane.

3. Farsightedness causes excessive use of accommodation, which can induce excessive convergence, leading to esophoria. Esophoria accounts for the highest proportion among all types of phoria.

bubble_chart Clinical Manifestations

When viewing distant objects, such as watching movies, sports games, walking, or observing scenery, symptoms become more noticeable. These may include headaches, eye pain, blurred vision, and general discomfort. Severe esophoria can impair localization and stereopsis functions. Patients with esophoria often prefer to look upward to alleviate symptoms, as doing so helps separate the eye positions and partially counteract the esophoria.

bubble_chart Treatment Measures

1. Cycloplegic Refraction: If farsightedness is present, it should be fully corrected to reduce accommodation and convergence. Astigmatism or anisometropia should also be corrected to improve visual acuity. For myopia, a lower degree of correction should be used to achieve better vision, as improved visual acuity can promote binocular vision function and fusion reflexes, which may also aid in treating esophoria.

2. Surgical Treatment: The surgical principle is as follows: if the esophoria is greater at distance than at near, bilateral lateral rectus muscle resection should be performed. If the esophoria is greater at near than at distance, bilateral medial rectus muscle recession should be performed. Recessing the medial rectus muscle by 1mm generally corrects approximately 4–6^△, with a fluctuation range of 2^△. Resecting the lateral rectus muscle by 1mm generally corrects approximately 3–4^△