Abstract:
To demonstrate new technology for low–cost, high resolution Spectral Domain Optical Coherence Tomography (SDOCT) optimized for real–time 2D (16 images/sec) and rapid 3D (6.67 sec/volume) imaging of the human retina in vivo.
A high–speed SDOCT system was constructed using a low–cost superluminescent diode source with a center wavelength at 841nm and FWHM bandwidth of 49nm. The SDOCT system acquired two–dimensional images consisting of 512 x 1000 pixels with an integration time of 50 µs/line, at a sustained rate of 16 images per second. Custom software performed spectral data acquisition, re–sampling from wavelength to wavenumber, numerical dispersion correction, Fourier transformation, live display, and optional data archiving in real time. For 3D volume acquisition, 6.67 second acquisition bursts comprising 100 vertically displaced 2D images were acquired under computer control. Three–dimensional data sets comprising up to 10mm x 4mm x 3mm retinal volumes were streamed to hard disk during this brief ocular fixation interval and post–processed to create 3D volumetric images and projections (Fig. 1).
The SDOCT system was measured to have axial resolution of 6 micrometers FWHM and 102 dB sensitivity. Real–time 2D images were completely void of motion artifact and allowed for visualization of retinal layers including clear delineation of the RPE and photoreceptor inner–outer segment boundary. Volumetric datasets permitted visualization of topographical features such as the optic nerve head and fovea, in addition to visualization of the vasculature akin to scanning laser ophthalmoscopy in projection views.
New technology for low–cost, high speed SDOCT allows for cross–sectional retinal imaging with apparent resolution approaching that of ultra–high–resolution OCT due to complete removal of motion artifact, without the need for expensive femtosecond laser light sources.
Keywords: anatomy • imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)