AIM: To measure the abnormality of the superior oblique tendon in patients with congenital superior oblique muscle paralysis.

METHODS: This is a cross-sectional, self-control designed study. The width and the tensity of the superior oblique tendon of both the paralytic and nonparalytic eye were measured during the operations in 22 patients who were diagnosed with esotropia(including congenital esotropia, basic esotropia and partially accommodative esotropia)accompanied with single superior oblique muscle paralysis. The tensity of the tendon was measured as the maximal distance of which the superior oblique tendon could be lifted from the sclera.

RESULTS: There was significant difference(P<0.01)in the average width of the superior oblique tendon between the paralytic eyes(2.64±0.69mm)and the nonparalytic eyes(3.84±0.56mm). There was also significant difference(P<0.01)in the average tensity between the paralytic eyes(9.02±1.68mm)and the nonparalytic eyes(6.48±1.33mm).

CONCLUSION: The superior oblique tendon is narrower and more relaxant in the paralytic eyes.