Kushner B J
Pediatric Eye Clinic, University of Wisconsin Medical Center, Madison.
Ophthalmology. 1989 Jan;96(1):127-32. doi: 10.1016/s0161-6420(89)32933-2.
The Parks three-step test is the standard for diagnosing which isolated cyclovertical muscle is palsied. It does not, however, tell the examiner if in fact one is dealing with a palsy of one cyclovertical muscle. Numerous other causes of vertical strabismus may have a positive Bielschowsky head tilt test. The use of the three-step test in these clinical situations may lead to incorrect diagnosis and treatment. These clinical conditions include contracture of the vertical recti, paresis of more than one vertical muscle, dissociated vertical divergence, previous vertical muscle surgery, skew deviation, myasthenia gravis, and small nonparalytic vertical deviations associated with horizontal strabismus. Several diagnostic steps in addition to the three-step test are necessary to tell if one is in fact dealing with a palsy of a single cyclovertical muscle.
帕克斯三步试验是诊断哪条孤立的垂直旋转肌麻痹的标准。然而，它并不能告知检查者所面对的是否确实是某一条垂直旋转肌的麻痹。垂直斜视的许多其他病因可能会使Bielschowsky头位倾斜试验呈阳性。在这些临床情况下使用三步试验可能会导致错误的诊断和治疗。这些临床情况包括垂直直肌挛缩、多条垂直肌麻痹、分离性垂直偏斜、既往垂直肌手术、斜歪、重症肌无力以及与水平斜视相关的小度数非麻痹性垂直偏斜。除了三步试验之外，还需要几个诊断步骤来判断所面对的是否确实是某一条垂直旋转肌的麻痹。
