Accommodation and Vergence Exercises Versus Prism Treatment for Small-angle Acute Acquired Concomitant Esotropia

Acute acquired concomitant esotropia (AACE) belongs to the category of concomitant strabismus. It is characterized by sudden onset, often accompanied by diplopia, and no change in the strabismus angle of each eye position. In recent years, with the increase in the use of smartphones and other screen devices, the incidence of AACE has been on the rise. Commonly used treatments in clinical practice include surgical treatment, botulinum toxin injection into the medial rectus muscle, and prism treatment. Patients with large-angle esotropia generally require surgical intervention to fundamentally correct patients eye positions and eliminate diplopia. However, surgical treatment requires waiting for six months in order to performed after the strabismus degree is stable. There are also risks of intraoperative trauma and secondary surgery. Patients with early and small-angle esotropia often choose prism treatment.

The principle of prism treatment is light refraction. After light is refracted through a prism, it falls on the fovea of the strabismic eye, eliminating diplopia. In the treatment of AACE, the main target population of prisms is patients with mild strabismus (the strabismus angle is usually less than 25 PD). Wearing prisms can eliminate diplopia and relieve related symptoms, but it does not really correct the strabismus problem.

The high incidence of AACE is related to excessive close work and use of electronic products. Excessive close eye use can lead to accommodative dysfunction. Studies have found that AACE patients have abnormal accommodative function. The accommodative function of AACE patients is weaker than normal, and the accommodation convergence to accommodation (AC/A) ratio is higher than normal. During clinical diagnosis and treatment, the accommodative function of AACE patients was examined and it was found that there was indeed abnormal accommodative function. Based on scientific research findings and the actual basis of clinical practice, improving accommodative function through accommodative training may be a good treatment option for early and small-angle AACE patients. However, existing studies have not fully explored the effectiveness and safety of accommodative exercise in the treatment of small-angle AACE, and there has been no study comparing the therapeutic outcomes of accommodative training and prism treatment on small-angle AACE.

In order to better guide clinical practice, we conducted a prospective, single-center, nonrandomized comparative study to objectively evaluate and compare the therapeutic effects of accommodative training and prism therapy on AACE. It is expected that the research results will provide more treatment options for AACE patients and provide important guidance for clinical selection of appropriate methods to treat small-angle AACE.