Heartbeat-Induced Axial Eye Motion Artifacts During Optical Coherence Tomography Measurements

Abstract

 

Purpose:

 

Motion artifacts in medical imaging can reduce the image quality and can lead to difficulty in clinical diagnoses. We investigate the cause of axial eye movements in optical coherence tomography (OCT), by simultaneous measurements of the macula and the heart beat in the finger. Understanding the cause of these motions can lead to improved image quality and Doppler flow measurement.

 

Methods:

 

5 measurements were done on 5 healthy volunteers. We collected Spectral domain-OCT B-scan images at a fixed position of the macula over a period up to 90 seconds. From the average a-scan we calculated the axial shift of every average B-scan with respect to the previous B-scan by calculating a cross-correlation. The calculated shifts versus time were Fourier transformed to analyze the frequency content. The dominant frequency was considered for further analysis. The heart beat was measured in the finger using an optical blood pressure detector (Nexfin, BMEYE b.v.). The blood pressure was digitized and Fourier transformed. The dominant frequency components of the OCT shift and blood pressure were compared.

 

Results:

 

We found a correlation of 0.94 between the dominant frequency in the OCT shift and in the heart beat rate.

 

Conclusions:

 

Axial motions in the retina during OCT volume scanning are likely caused by the heartbeat.  

 

Keywords: imaging/image analysis: clinical • eye movements • retina