title: Limbus-insertion distance of superior rectus in primary angle closure glaucoma: an anterior segment OCT study.
abstract: OBJECTIVE
  To compare the distance from the corneoscleral limbus to the insertion site of the superior rectus of primary angle-closure glaucoma (PACG) patients with normal controls and to identify potential characteristics associated with limbus-insertion distance.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  A total of 92 subjects (eyes) were enrolled in the study: 35 were nonglaucoma controls and 57 were PACG patients.
  
  
  METHODS
  The limbus-insertion distance of the superior rectus was measured by anterior segment optical coherence tomography (AS-OCT) and intraoperative surgical caliper. The anterior chamber parameters were also measured using AS-OCT to identify potential characteristics associated with limbus-insertion distance.
  
  
  RESULTS
  The limbus-insertion distance of the superior rectus was 0.40 ± 0.08 mm shorter in the PACG group than in the normal control group (p < 0.001). Anterior segment parameter values, including anterior chamber depth (ACD), anterior chamber width (ACW), anterior chamber area (ACA), and anterior chamber volume (ACV), were smaller in the PACG group than in the normal control group, but the lens vault was larger (all p < 0.001). A shorter limbus-insertion distance of the superior rectus was significantly associated with shorter axial length and "crowded" angle (smaller ACD, ACW, ACA, and ACV) (all p < 0.05).
  
  
  CONCLUSIONS
  This is the first study to demonstrate that the limbus-insertion distance of the superior rectus was shorter in PACG eyes than in normal eyes. The shorter limbus-insertion distance may be another anatomic characteristic of PACG eyes.
authors.affiliation: Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, People's Republic of China.
authors.forename: Wenbin
authors.initials: W
authors.lastname: Huang
authors.affiliation: Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, People's Republic of China.
authors.forename: Xinbo
authors.initials: X
authors.lastname: Gao
authors.affiliation: Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, People's Republic of China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, People's Republic of China.. Electronic address: zhangxl2@mail.sysu.edu.cn.
authors.forename: Xiulan
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000368:Aged; D000869:Anterior Eye Segment / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000000981:diagnostic imaging* / Q000601:surgery; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D016850:Limbus Corneae / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular