title: Comparison of corneal versus through-the-lid A-scan ultrasound biometry.
abstract: BACKGROUND
  Accurate ultrasonography data on axial ocular dimensions in infants and toddlers are essential for understanding ocular development. Conventional methods using corneal contact with topical anesthesia but without sedation are not feasible for most of these patients. We evaluate an alternative method which places the probe on the closed eyelid.
  
  
  METHODS
  We compared A-scan ultrasound biometry measurements taken with the probe directly on the cornea with those with the probe on the closed eyelid on the right eye of 35 young adult subjects.
  
  
  RESULTS
  There was no significant difference between methods for mean anterior chamber depth (corneal = 3.83 mm, lid = 3.87 mm, p = 0.13, paired t-test). The mean lens thickness (corneal = 3.63 mm, lid = 3.75 mm, p = 0.0001, paired t-test) and mean vitreous chamber depth (corneal = 17.50 mm, lid = 17.68 mm, p = 0.0440, paired t-test) were significantly different.
  
  
  CONCLUSIONS
  Ultrasonography through the closed eyelid appears to be a viable method with acceptable validity compared with corneal ultrasound. Poorer agreement for lens thickness and vitreous chamber depth may be undesirable, but these data should be useful for planning future studies of infants and toddlers.
authors.affiliation: School of Optometry, University of California, Berkeley, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Twelker
authors.forename: S
authors.initials: S
authors.lastname: Kirschbaum
authors.forename: K
authors.initials: K
authors.lastname: Zadnik
authors.forename: D O
authors.initials: DO
authors.lastname: Mutti
mesh_terms: D000328:Adult; D001699:Biometry; D003315:Cornea / Q000000981:diagnostic imaging; D005123:Eye / Q000000981:diagnostic imaging*; D005143:Eyelids / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008297:Male; D014463:Ultrasonography