title: Heartbeat-induced axial motion artifacts in optical coherence tomography measurements of the retina.
abstract: OBJECTIVE
  To investigate the cause of axial eye motion artifacts that occur in optical coherence tomography (OCT) imaging of the retina. Understanding the cause of these motions can lead to improved OCT image quality and therefore better diagnoses.
  
  
  METHODS
  Twenty-seven measurements were performed on 5 subjects. Spectral domain OCT images at the macula were collected over periods up to 30 seconds. The axial shift of every average A-scan was calculated with respect to the previous average A-scan by calculating the cross-correlation. The frequency spectrum of the calculated shifts versus time was determined. The heart rate was determined from blood pressure measurements at the finger using an optical blood pressure detector. The fundamental frequency and higher order harmonics of the axial OCT shift were compared with the frequency spectrum of blood pressure data. In addition, simultaneous registration of the movement of the cornea and the retina was performed with a dual reference arm OCT setup, and movements of the head were also analyzed.
  
  
  RESULTS
  A correlation of 0.90 was found between the fundamental frequency in the axial OCT shift and the heart rate. Cornea and retina move simultaneously in the axial direction. The entire head moves with the same amplitude as the retina.
  
  
  CONCLUSIONS
  Axial motion artifacts during OCT volume scanning of the retina are caused by movements of the whole head induced by the heartbeat.
authors.affiliation: Department of Biomedical Engineering & Physics, University of Amsterdam, Amsterdam, The Netherlands. r.dekinkelder@amc.nl
authors.forename: Roy
authors.initials: R
authors.lastname: de Kinkelder
authors.forename: Jeroen
authors.initials: J
authors.lastname: Kalkman
authors.forename: Dirk J
authors.initials: DJ
authors.lastname: Faber
authors.forename: Olaf
authors.initials: O
authors.lastname: Schraa
authors.forename: Pauline H B
authors.initials: PH
authors.lastname: Kok
authors.forename: Frank D
authors.initials: FD
authors.lastname: Verbraak
authors.forename: Ton G
authors.initials: TG
authors.lastname: van Leeuwen
mesh_terms: D000328:Adult; D016477:Artifacts; D058452:Axial Length, Eye; D001794:Blood Pressure / Q000502:physiology; D005133:Eye Movements / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D009038:Motion; D012160:Retina / Q000033:anatomy & histology*; D041623:Tomography, Optical Coherence / Q000295:instrumentation*