PURPOSE: Although the Parks-Bielschowsky three-step test is the cornerstone of cyclovertical strabismus diagnosis, it has not been validated against an external benchmark. We evaluated the test's sensitivity in clinical diagnosis of @entity6125 in @entity1 with unequivocal magnetic resonance imaging (MRI) evidence of superior oblique @entity194 . METHODS: A total of 73 strabismic @entity1 were selected from a prospective MRI study because they exhibited superior oblique @entity194 indicative of superior oblique denervation and thus confirmatory of @entity6125 . Of these, 50 @entity1 who had no confounding factors were included for detailed study. Ocular motility data were evaluated to determine sensitivity of single and combined clinical findings in diagnosis of @entity6125 . RESULTS: Maximum mean ipsilesional superior oblique cross section was reduced to 9.6    0.6 mm(2) (mean    standard error) in @entity6125 , representing 52% of the 18.5    0.6 mm(2) contralesional superior oblique maximum cross section and 52% of the 18.4    0.4 mm(2) control maximum superior oblique cross section (P < 0.001). Of the 50 @entity1 , 35 (70%) with superior oblique @entity194 fulfilled the entire three-step test. In 14 (28%) @entity1 two steps were fulfilled; in 1 @entity1 (2%), only one step. Affected superior oblique cross section was similar in orbits that fulfilled the three-step test (9.8    0.9 mm(2)) and those that did not (9.1    0.7 mm(2); P = 0.58). CONCLUSIONS: The complete three-step test fails to detect 30% of cases of superior oblique @entity194 . Often only two of three steps are positive in @entity6125 .

Sensitivity of the three-step test in diagnosis of XXXX .

@entity6125 :: ('MESH:D020432', 'Disease') :: ['superior oblique palsy'] @entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity194 :: ('MESH:D001284', 'Disease') :: ['atrophy']
@entity6125 :: (MESH:D020432,Disease) :: ['superior oblique palsy']
