title: [The clinical features and surgical treatment of masked bilateral superior oblique palsy].
abstract: OBJECTIVE
  To investigate the clinical features, diagnosis and the management of masked bilateral superior oblique palsy (MBSOP).
  
  
  METHODS
  Retrospectively analyzed the records of all 7 patients that met the clinical criteria for MBSOP in Zhongshan Ophthalmic Center between 1999 and 2003. The head tilt, vertical deviation in primary position and the action of obliquus pre- and postoperatively were collected in detail.
  
  
  RESULTS
  All 7 patients were diagnosed as unilateral SOP in the first time. The average hypertropia in primary position preoperatively was 19.7(Delta) (range 6(Delta) to 30(Delta)). All patients had a head tilt, obvious unilateral inferior oblique overaction (+2 to +4) and mild superior oblique underaction (-1 to -2), and normal action in contralateral superior and inferior obliquus. Initial surgery consisted of ipsilateral inferior oblique weakening with (5 patients) or without (2 patients) ipsilateral superior rectus recession. The average hypertropia in primary position was 12.0(Delta) (range 0(Delta) to 20(Delta)) after the first operation. In 1 week to 4 years, all of the previously masked eye presented the inferior oblique overaction (+2 to +3) and superior oblique underaction (0 to -1). All patients underwent a second surgery in 4 months to 4 years after the initial surgery. The average hypertropia in primary position was 2.3(Delta) (range 0(Delta) to 7(Delta)) after the second operation. Postoperative alignment was excellent in all patients.
  
  
  CONCLUSIONS
  Masked bilateral superior oblique palsy is quite difficult to detect before surgical correction of the initial manifest palsy. The possibility of an occult contralateral palsy should be considered in all undergoing surgery for unilateral SOP. The superior rectus recession and the inferior oblique weakening procedure should be performed at different stages. When the masked palsy becomes evident, a successful surgical outcome can usually be expected.
authors: Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. ghm44@163.com
authors: Guang-huan
authors: GH
authors: Mai
authors: Huan-yun
authors: HY
authors: Yu
authors: Xin-ping
authors: XP
authors: Yu
authors: Jing-chang
authors: JC
authors: Chen
authors: Xiao-ming
authors: XM
authors: Lin
authors: Da-ming
authors: DM
authors: Deng
authors: He-ping
authors: HP
authors: Wu
authors: Ying
authors: Y
authors: Kang
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D009886:Ophthalmoplegia / Q000150:complications / Q000175:diagnosis* / Q000601:surgery*; D012189:Retrospective Studies; D013285:Strabismus / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery*