title: Enhanced depth imaging spectral domain optical coherence tomography versus ultrasonography B-Scan for measuring retinochoroidal thickness in normal eyes.
abstract: OBJECTIVE
  To assess the accuracy of retinochoroidal thickness measurements obtained by ultrasonography (USG) B-Scan (over eyelids) and high-resolution immersion USG (with lids open) compared with enhanced depth imaging optical coherence tomography (EDI-OCT) in normal subjects.
  
  
  METHODS
  Retinochoroidal thickness measurements were performed in normal subjects using USG over eyelids and high-resolution immersion USG (with lids open) using the 20-MHz probe keeping EDI-OCT as the gold standard. Mean retinochoroidal thickness at the fovea, 1.5 mm nasally and temporally were analyzed for interobserver agreement using intraclass correlation coefficient test. Paired t-test was used to compare the values obtained by the three techniques. A 10% difference was defined as clinically significant in the measurements obtained using USG compared with EDI-OCT.
  
  
  RESULTS
  Thirty-two eyes of 18 healthy volunteers (15 men) with normal baseline ophthalmologic examination (spherical equivalent, -2 to +2 diopter) were enrolled. Retinochoroidal thickness measurements showed good interobserver agreement for EDI-OCT (intraclass correlation coefficient = 0.999), immersion USG (intraclass correlation coefficient = 0.983), and USG over eyelids (intraclass correlation coefficient = 0.97). Mean retinochoroidal thickness using the above 3 techniques measured 631.77 ± 98.48, 617.17 ± 95.22, and 953 ± 151.28 μm, respectively. Immersion USG measurements were not significantly different from the gold standard, that is, EDI-OCT. However, over eyelids USG provided significantly higher values (P < 0.001) when compared with EDI-OCT and immersion USG.
  
  
  CONCLUSIONS
  Ultrasonography over eyelids overestimates the retinochoroidal thickness. Immersion USG provides values comparable with EDI-OCT and high-quality imaging where EDI-OCT cannot be performed.
authors.affiliation: *Department of Ophthalmology, Advanced Eye Centre, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India; †Department of Biomedical and Clinical Science, Eye Clinic, Luigi Sacco Hospital, University of Milan, Milano, Italy; ‡Department of Ophthalmology and Visual Sciences, Stanley M. Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, Nebraska; and §Retina Services Center for Sight, New Delhi, India.
authors.forename: Ramandeep
authors.initials: R
authors.lastname: Singh
authors.forename: Alessandro
authors.initials: A
authors.lastname: Invernizzi
authors.forename: Aniruddha
authors.initials: A
authors.lastname: Agarwal
authors.forename: Neha
authors.initials: N
authors.lastname: Kumari
authors.forename: Amod
authors.initials: A
authors.lastname: Gupta
mesh_terms: D000328:Adult; D002829:Choroid / Q000033:anatomy & histology*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D012016:Reference Values; D012160:Retina / Q000033:anatomy & histology*; D041623:Tomography, Optical Coherence; D014463:Ultrasonography; D055815:Young Adult