title: Comparison of anterior segment measurements by 3 Scheimpflug tomographers and 1 Placido corneal topographer.
abstract: OBJECTIVE
  To compare the anterior segment measurements provided by 3 Scheimpflug tomographers and a Placido corneal topographer.
  
  
  METHODS
  Private clinical ophthalmology practice.
  
  
  METHODS
  Evaluation of diagnostic test or technology.
  
  
  METHODS
  In a sample of 25 consecutive patients having either refractive or cataract surgery, the anterior eye segment was analyzed by means of a rotating Scheimpflug camera (Pentacam), 2 devices with a Scheimpflug camera combined with a Placido disk (Sirius and TMS-5), and a Placido disk corneal topographer (Keratron). Measurement results were compared using analysis of variance. Agreement was assessed using Bland-Altman plots.
  
  
  RESULTS
  The mean simulated keratometry (K) was different between the 4 instruments (P<.0001), with Keratron providing the highest value (44.43 diopters [D] ± 1.28 [SD]). The Pentacam and Sirius provided the lowest values (44.05 ± 1.21 D and 44.05 ± 1.27 D, respectively), without statistical difference (posttest). The mean posterior corneal power and minimum corneal thickness were statistically different between the 3 Scheimpflug cameras (P<.0001 and P=.0210, respectively); 95% limits of agreement, however, were narrow for posterior corneal power and large for corneal thickness. The only 2 devices measuring the distance between the corneal endothelium and the anterior lens surface showed a statistically but not clinically significant difference (2.90 ± 0.48 mm and 2.94 ± 0.47 mm, respectively). There were no statistically significant differences in anterior corneal asphericity between the 4 instruments.
  
  
  CONCLUSIONS
  Although the measurements of some parameters by different instruments were similar, caution is warranted before using them interchangeably.
authors.affiliation: G.B. Bietti Eye Foundation-IRCCS, Rome, Italy. giacomo.savini@alice.it
authors.forename: Giacomo
authors.initials: G
authors.lastname: Savini
authors.forename: Michele
authors.initials: M
authors.lastname: Carbonelli
authors.forename: Alessandra
authors.initials: A
authors.lastname: Sbreglia
authors.forename: Piero
authors.initials: P
authors.lastname: Barboni
authors.forename: Giulia
authors.initials: G
authors.lastname: Deluigi
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Hoffer
mesh_terms: D000869:Anterior Eye Segment / Q000473:pathology*; D001699:Biometry / Q000295:instrumentation; D002387:Cataract Extraction; D048988:Corneal Surgery, Laser; D019781:Corneal Topography / Q000295:instrumentation* / Q000592:standards; D004728:Endothelium, Corneal / Q000473:pathology; D006801:Humans; D007908:Lens, Crystalline / Q000473:pathology; D008875:Middle Aged; D010781:Photography / Q000295:instrumentation* / Q000592:standards; D011446:Prospective Studies; D015203:Reproducibility of Results; D014054:Tomography / Q000295:instrumentation