AIM: To observe the clinical effect of external rectus muscle amputation in the treatment of divergence insufficiency.

METHODS: A retrospective analysis of 37 cases of insufficiency in our hospital from February 2011 to October 2017. The clinical manifestations were hyperopic esotropia with ipsilateral diplopia, myopia implicit esotropia without diplopia, and the monocular and binocular movements were normal. Preoperative refractive, strabismus, near stereopsis, negative fusion force examination, and then single or double external rectus muscle surgery.

RESULTS: Double vision disappeared after all cases, and there was no recurrence in diplopia after one year of follow-up. The preoperative long-term internal strabismus was +15^△-+28^△, with an average of 18.4^△±5.7^△, the near-internal strabismus was +5^△-+16^△, the average was 10.3^△±3.6^△, The difference value of long distance and short distance strabismus was 8.1^△±2.3^△; one week after surgery, the distance strabismus was -5.4^△±1.5^△, the near-distance squint was -7.2^△±1.6^△, the difference value was 1.8^△±0.6^△; the one year postoperative strabismus was -1.9^△±1.2^△, the close squint was -3.4^△±1.4^△, the difference value was 1.5^△±0.8^△. The long-distance strabismus one week after operation and one year after operation was significantly lower than that before operation(P<0.05). The difference of distance and strabismus between one week and one year after operation was statistically significant. Preoperative the difference between near and far squint one week and one year after operation was statistically significant(P<0.05). The difference was statistically significant between the preoperative and postoperative one week. The difference was statistically significant 1 week after surgery and 1 year after surgery. The long-distance negative fusion force before surgery was 3^△-9^△, with an average of 5.1^△±1.8^△, and the near-negative fusion force was 15^△-24^△, with an average of 19.4^△±3.2^△. The long-near negative fusion force was 10.1^△±3.3^△, 19.7^△±4.1^△ at 1wk after operation, and the long-distance negative fusion force was 11.2^△±3.6^△, 20.2^△±4.8^△ for one year after operation. There was a statistically significant difference between the patients with preoperative and one week postoperative negative fusion(q=4.551, P=0.013). There was no significant difference between the one week and one year after surgery(q=0.713, P=0.115).There was no significant difference in the patients' brachytherapy before and after one week and one year after operation(P>0.05).

CONCLUSION: Divergence insufficiency of external rectus muscle surgery can effectively reduce the difference of long-distance strabismus after surgery, eliminate the symptoms of diplopia in patients, and improve the near stereoscopic sharpness and long-distance negative fusion force.