Does transverse chromatic aberration limit performance of AO-OCT retinal imaging?

Abstract

The combination of adaptive optics (AO) and optical coherence tomography (OCT) has been successfully applied to in vivo retinal imaging, motivated by the potential of unprecedented 3D resolution. The eye, however, not only suffers from monochromatic aberrations, which are corrected by AO, but also substantial chromatic aberrations, which are not. To correct chromatic aberrations, achromatizing lenses have been recently employed in ultrahigh resolution AO-OCT instruments. These lenses, like their earlier predecessors for vision improvement, effectively correct the eye's longitudinal chromatic aberration (LCA), but make no attempt at the complementary transverse chromatic aberration (TCA). This raises an important concern as to the degrading impact of TCA on the 3D resolution of AO-OCT and OCT retina cameras. To address this, we undertook a theoretical analysis of TCA for high-resolution retinal imaging. The theoretical analysis included the two primary contributors of TCA for retinal imaging: (1) errors in the lateral positioning of the eye and (2) off-axis imaging. The analysis predicted the extent to which TCA impacts retinal imaging and the conditions under which it can be held at acceptable levels for AO-OCT and OCT. Several near-infrared bands were chosen that correspond to common OCT light sources.