title: Comparative estimation of anterior chamber depth by ultrasonography, Orbscan II, and IOLMaster.
abstract: OBJECTIVE
  To assess the degree of agreement of anterior chamber depth (ACD) measurements by 2 optical devices (Orbscan II and IOLMaster) and compare them with contact ultrasound A-scan.
  
  
  METHODS
  Department of Ophthalmology at Hull Royal Infirmary, England. methods: In this prospective study of 81 eyes of 41 consecutive patients, ACD estimation was done by 3 methods-scanning slit topography (Orbscan II), partial coherence interferometry (IOLMaster), and contact ultrasound A-scan in that order. The same observer performed all measurements. Repeated measures Analysis of Variance (ANOVA) was used to analyze difference between ACD measurements by the 3 methods. Difference in measurements between methods was assessed using the paired t test.
  
  
  RESULTS
  The mean ACD (+/-SD) by the 3 methods was 3.32 mm (0.60), 3.33 mm (0.61), and 2.87 mm (0.55), respectively. There was a statistically significant difference between measurements recorded by the 3 methods (P<.01). Mean contact A-scan measurements were 0.40 mm and 0.43 mm lower than by Orbscan II and IOLMaster respectively (P<.01).
  
  
  CONCLUSIONS
  Applanation ultrasound gives consistently lower measurements for ACD compared to Orbscan II and IOLMaster. Although a high degree of agreement between Orbscan II and IOLMaster was noted, further studies are needed to assess the interchangeability of measurements in clinical practice.
authors.affiliation: Leeds Teaching Hospitals, University of Teesside, Middlesbrough, England, United Kingdom. arreddy@rcsed.ac.uk
authors.forename: Aravind R
authors.initials: AR
authors.lastname: Reddy
authors.forename: Milind V
authors.initials: MV
authors.lastname: Pande
authors.forename: Paul
authors.initials: P
authors.lastname: Finn
authors.forename: Hazem
authors.initials: H
authors.lastname: El-Gogary
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000000981:diagnostic imaging*; D001699:Biometry / Q000295:instrumentation*; D001837:Body Weights and Measures; D002386:Cataract / Q000150:complications; D002387:Cataract Extraction; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D014463:Ultrasonography