High Penetration and High Resolution Adaptive Optics Spectral Domain Optical Coherence Tomography With One-Micrometer Probe

Abstract

 

Purpose:

 

Adaptive optics spectral domain optical coherence tomography (AO SD-OCT) enables high isotropic resolution (3.6 µm x 3.6 µm x 3.4 µm) for in vivo retinal imaging. We enhance the penetration depth of AO SD-OCT by using one-micrometer probe and demonstrated high penetration and high resolution imaging of retina and choroid.

 

Methods:

 

Seven eyes of 7 normal subjects were examined by AO SD-OCT. A broadband 1.03 µm SLD light source (a band width of 106 nm) was used as a probing beam providing a depth resolution of 3.4 µm in tissue. An InGaAs line-scan camera acquired 47,000 depth-scans/s. The AO system was configured with a single magnetic deformable mirror (Mirao52, Imagine Eyes) and a Shack-Hartmann wavefront sensor. The AO closed loop operates at 7 Hz and the measured residual RMS wavefront error was less than 0.1 µm which provided a transversal resolution of 3.6 µm on the retina. Seven eyes of 7 normal subjects were involved in this study. The field-of-view was 4.5 degree. The patch of retina at an eccentricity of about 6 degrees nasal was scanned iteratively and 5 frames are averaged to reduce speckles.

 

Results:

 

The waving interface between a nerve fiber layer (NFL) and a ganglion cell layer (GCL) was observed for 6 of the 7 subjects. This waving appearance may reflect the cross-sectional structure of nerve fiber bundles. The interface between GCL and inner plexiform layer were observed for 7 of the 7 subjects. The chorio-scleral interface was observed for 5 of the 7 subjects. This implies high penetration of the one-micrometer probe.

 

Conclusions:

 

The detailed visualization of NFL, GCL and choroid makes the AO SD-OCT useful not only for the investigation of photoreceptors but also for glaucoma.  

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • nerve fiber layer • choroid