METHODS:Twenty-one cases(42 eyes)with muscular asthenopia caused by esophoria were included. After examination of refraction, phoria and fusion function, all cases were given operative treatment to correct esophoria.

RESULTS:At 1wk after surgery, clinical symptoms were improved evidently in all cases, such as headache, diplopia and eye swelling. After followed up for 1a, no recrudescence was found. Before surgery, at 1wk and 1a after surgery, esophoria in the distance were 20.3^△±6.3^△,-3.1^△±1.4^△,0.7^△±1.6^△ respectively and esophoria in the near distance were 10.5^△±3.1^△,-1.3^△±0.6^△,1.5^△±0.8^△ respectively. By comparison of esophoria before and after surgery in different stages separately, the differences were statistically(P<0.01). There was no statistically difference between different stages about negative fusional power in the distance and near distance(P>0.05).

CONCLUSION:Esophoria operation may relieve obviously muscular asthenopia caused by esophoria without changing fusion function.