Abstract
Purpose :
To develop a high speed, high resolutoion SD-OCT system for in-vivo volumetric imaging of the structure and blood vasculature of the human retina.
Methods :
A compact, fiberoptic SD-OCT system that conbines high axial resolution with rapid image acquisition rate, was build for in-vivo volumetric imaging of the human retina. The system is powered by a femtosecond laser (Integral, Femntolasers) with emission spectrum centered at ~790 nm and spectral bandwidth of ~140 nm (measured at the detection end of the OCT system). The retinal imaging probe consisted of 3 achromat lenses (f1 = 10 mm, f2 = f3 = 60 mm) and a pair of galvanometric scanners (6210, Cambridge Technologies). Both a 25 mm water cell and a pair of BK7 prisms were used to compensate for dispersion mismatch within the OCT system and the eye. The detection end of the SD-OCT system was comprised of a customized, high resolution spectrometer (Cobra, Wasatch Photonics), interfaced with a linear array CMOS camera (OCTOPLUS CL, e2v, Teledyne Dalsa). The camera has a tall pixel design, 2048 pixels and 250 kHz data acquisition rate. A high speed framegrabber (Teledyne Dalsa) was used to acquired the raw data. Custom Matlab-based software was used to generate imnages from the raw data and compensate for eye motion induced image artefacts in the retina OCT images.
Results :
The axial OCT resolution was measured to be ~ 2.2 µm in free space, corresponding to ~ 1.6 µm in retinal tissue assuming an average refractive index of 1.38. The system’s sensitivity was ~98 dB, measured at ~ 100 µm away from the zero delay line for 850 µW incident optical power. SNR roll-off was ~10 dB over a scanning range of ~ 1.4 mm. Volumetric images of the human retina, acquired in-vivo from healthy subjects, show the detailed structure of all retinal layers.
Conclusions :
We have developed a SD-OCT system for in-vivo human retinal imaging that combines high axial resolution with rapid image acquisition rate.
This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.