Adaptive optics - optical coherence tomography for in vivo retinal imaging: effects of spectral bandwidth on image quality

Adaptive Optics - Optical Coherence Tomography (AO-OCT) has demonstrated a promising improvement in lateral resolution for retinal imaging compared to standard OCT. Recent developments in Fourier-domain OCT technology allow AO-OCT instruments to acquire three-dimensional (3D) retinal structures with high speed and high "volumetric" resolution (in all three dimensions). One of the most important factors (besides acquisition speed) that will determine the true potential of this technique is its ability to achieve diffraction-limited lateral resolution (~3 μm) while operating in the ultrahigh axial resolution range (~3 μm) offered by OCT. Theoretical studies have shown that the eye's chromatic aberrations may drastically reduce volumetric resolution. This is a critical finding because for "standard" stand alone ultrahigh OCT, increasing the spectral bandwidth of the light source improves axial resolution without compromising lateral resolution. To study the effects of spectral bandwidth on AO-OCT systems for retinal imaging two different light sources offering 6 and 3 μm axial resolution were tested. This comparison was based on both AO correcting system performance as well as the quality of corresponding OCT images.