title: Biometric parameters in different stages of primary angle closure using low-coherence interferometry.
abstract: OBJECTIVE
  To compare ocular biometric parameters using low-coherence interferometry among siblings affected with different degrees of primary angle closure (PAC).
  
  
  METHODS
  In this cross-sectional comparative study, a total of 170 eyes of 86 siblings from 47 families underwent low-coherence interferometry (LenStar 900; Haag-Streit, Koeniz, Switzerland) to determine central corneal thickness, anterior chamber depth (ACD), aqueous depth (AD), lens thickness (LT), vitreous depth, and axial length (AL). Regression coefficients were applied to show the trend of the measured variables in different stages of angle closure. To evaluate the discriminative power of the parameters, receiver operating characteristic curves were used. Best cutoff points were selected based on the Youden index. Sensitivity, specificity, positive and negative predicative values, positive and negative likelihood ratios, and diagnostic accuracy were determined for each variable.
  
  
  RESULTS
  All biometric parameters changed significantly from normal eyes to PAC suspects, PAC, and PAC glaucoma; there was a significant stepwise decrease in central corneal thickness, ACD, AD, vitreous depth, and AL, and an increase in LT and LT/AL. Anterior chamber depth and AD had the best diagnostic power for detecting angle closure; best levels of sensitivity and specificity were obtained with cutoff values of 3.11 mm for ACD and 2.57 mm for AD.
  
  
  CONCLUSIONS
  Biometric parameters measured by low-coherence interferometry demonstrated a significant and stepwise change among eyes affected with various degrees of angle closure. Although the current classification scheme for angle closure is based on anatomical features, it has excellent correlation with biometric parameters.
authors.affiliation: *MD †MSc Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran (all authors).
authors.forename: Shahin
authors.initials: S
authors.lastname: Yazdani
authors.forename: Shadi
authors.initials: S
authors.lastname: Akbarian
authors.forename: Mohammad
authors.initials: M
authors.lastname: Pakravan
authors.forename: Azadeh
authors.initials: A
authors.lastname: Doozandeh
authors.forename: Mohsen
authors.initials: M
authors.lastname: Afrouzifar
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000473:pathology*; D001082:Aqueous Humor / Q000502:physiology*; D058452:Axial Length, Eye / Q000473:pathology; D001699:Biometry; D003315:Cornea / Q000473:pathology*; D003430:Cross-Sectional Studies; D005189:False Positive Reactions; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000145:classification* / Q000175:diagnosis* / Q000601:surgery; D006801:Humans; D007368:Interferometry; D007429:Intraocular Pressure; D007908:Lens, Crystalline / Q000473:pathology*; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D035781:Siblings; D014065:Tonometry, Ocular