Novel Optical Coherence Tomography for Imaging the Entire Anterior Segment of the Eye

Abstract

 

Purpose:

 

To develop and test novel optical coherence tomography for imaging the entire anterior segment of the human eye.

 

Methods:

 

Two novel OCT systems were developed to achieve the scan depth more than 11mm, which is enough for imaging the entire anterior segment of the human eye. The first system featured 7.3mm scan depth which was doubled using alterative two reference arms. The alteration between two reference arms was synchronized with the scanning and equivalent 14.6mm scan depth was displayed in real-time. The second system featured a specially designed spectrometer for scan depth of 11mm. Image enhancement was used by overlaying two images with the alternative placement of the zero-delay line on the top and bottom. This method was used to compensate the drop of signal to noise ratio through the entire image depth. A superluminescent diode-based light source with 840 nm center wavelength and 50nm bandwidths was used in both systems. The scan speed was set to 24K A-scan/s. Five eyes of 5 healthy subjects were imaged in two visits with both systems.

 

Results:

 

The entire anterior segment of all 5 eyes was successfully visualized with both systems (Figure). No significant differences were found between visits and systems in all measurements (P>0.05). The anterior chamber depth (ACD) was 3058 ± 274µm with system 1 and 3067 ± 272µm with system 2. The crystalline lens thickness (CLT) was 4140 ± 190µm with system 1 and 3999 ± 272µm with system 2. The correlation coefficient between both systems was 0.96 for ACD and 0.62 for CLT.

 

Conclusions:

 

We demonstrated two novel OCT systems with the scan depth more than enough for imaging the entire anterior segment of the human eye. Both approaches appeared suitable for studying presbyopia and accommodation.  

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • anterior segment • accommodation