Recording Eye Movement Along the Z-Axis Using High Speed Ultrahigh Resolution Optical Coherence Tomography

Abstract

 

Purpose:

 

To quantify previously undocumented eye movement along the z-axis (antero-posterior) using high speed ultrahigh resolution optical coherence tomography (hsUHR-OCT).

 

Methods:

 

Using a hsUHR-OCT device, we obtained 360 sequential line scans (256 a-scans along a single 6 mm horizontal line passing the fovea, scan time ~3.84 seconds) in seven healthy subjects. An M-mode image (sampling frequency 93.7 Hz) was generated by averaging 5 adjacent sampling points that showed a consistently high signal level. The spatial location of the retina was recorded by identifying the internal limiting membrane (ILM) in each scan assuming that ILM location represented the retinal spatial location along the z-axis. A model eye was also scanned as a stationary control.

 

Results:

 

No movement was detected on measurements using the model eye. Regular sine-waveform eye movements on z-axis were recorded for each subject. The mean of peak-to-peak amplitude of the eye movements was 25.8 ± 18.3µm and the mean peak-to-peak duration was 94.2 ± 39.6ms. The mean frequency of the eye movements was 5.33 Hz, ranging from 2.83 to 9.35 Hz. Main-sequence plot showed that durations of each forward or backward movement were significantly correlated with their amplitudes (R²=0.472, p<0.0001, Pearson correlation).

 

Conclusions:

 

Z-axis eye movements were recorded for the first time using hsUHR-OCT. The z-axis eye movements fitted a main-sequence relationship between their durations and amplitudes. This novel method may provide interesting and previously unreported insights into ocular motor system.  

 

Clinical Trial:

 

www.clinicaltrials.gov NCT00343746

 

Keywords: eye movements: recording techniques • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)