title: Anterior chamber depth measurement in pseudophakic eyes: a comparison of Pentacam and ultrasound.
abstract: OBJECTIVE
  To compare the anterior chamber depth (ACD) measurements of a Scheimpflug camera (Pentacam, Oculus Optikgeräte GmbH) and immersion ultrasound biometry (UltraScan Imaging System, Alcon Laboratories) in pseudophakic eyes.
  
  
  METHODS
  This prospective, multicenter study included three independent sample groups. The ACD, defined as the distance between the corneal epithelium and intraocular lens anterior surface, was assessed by ultrasound biometry. Two Pentacam ACD measurements were evaluated--the value automatically provided by the internal software and a manual measurement obtained by moving the software calipers on a single Scheimpflug image.
  
  
  RESULTS
  For the comparison group (12 eyes), no significant difference between the mean ultrasound biometry and mean Pentacam manual measurement (4.51+/-0.34 mm and 4.50+/-0.34 mm, respectively, P>.05) was noted, whereas the mean automatic value was significantly higher (4.94+/-0.41 mm, P=.0002), as the posterior edge of the anterior chamber is erroneously identified as coinciding with the boundary of the posterior capsule. A strong correlation was found between Pentacam manual measurements and ultrasound biometry (r=0.98, P<.0001); this correlation was confirmed by the confirmation group (17 eyes), whose mean values were 4.76+/-0.39 mm and 4.72+/-0.37 mm, respectively (r=0.98, P<.0001). After merging the data for the comparison and confirmation groups, the difference between Pentacam manual measurements (4.65+/-0.38 mm) and ultrasound readings (4.63+/-0.38 mm) was not statistically significant. For the assessment group (15 eyes), relative repeatability and reproducibility of Pentacam manual measurements were 1.17% and 1.59%, respectively.
  
  
  CONCLUSIONS
  In pseudophakic eyes, the Pentacam provides ACD values that do not statistically differ from those of ultrasound immersion biometry, on the condition that manual measurements are used rather than automatic ones.
authors.affiliation: G.B. Bietti Eye Foundation-IRCCS, Via Livenza 3, Rome, Italy. giacomo.savini@alice.it
authors.forename: Giacomo
authors.initials: G
authors.lastname: Savini
authors.forename: Thomas
authors.initials: T
authors.lastname: Olsen
authors.forename: Claudio
authors.initials: C
authors.lastname: Carbonara
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Pazzaglia
authors.forename: Piero
authors.initials: P
authors.lastname: Barboni
authors.forename: Michele
authors.initials: M
authors.lastname: Carbonelli
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Hoffer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000473:pathology*; D000886:Anthropometry / Q000379:methods*; D001699:Biometry; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D019654:Lens Implantation, Intraocular; D008875:Middle Aged; D018918:Phacoemulsification; D010781:Photography / Q000379:methods; D011446:Prospective Studies; D019591:Pseudophakia / Q000473:pathology*; D014463:Ultrasonography / Q000379:methods