Ultrahigh Speed OCT Imaging of the Retina at 70,000 to 312,500 Axial Scans Per Second

Abstract

Purpose: : The current generation of commercial ophthalmic OCT imaging systems operate with ~5 um axial resolution at speeds of 26,000 to 50,000 axial scans per second. This investigation demonstrates the feasibility of acquiring dense 3D volumetric data sets with minimal motion artifacts using new ultrahigh speed spectral / Fourier domain OCT at 70,000 to 312,500 axial scans per second. The higher speeds and higher density data sets promise to enable improved en face visualization methods, reduce eye motion artifacts and improve detection and tracking of focal disease.

Methods: : An ultrahigh speed spectral / Fourier domain prototype OCT instrument was developed using new high speed CMOS imaging technology. Different spectrometer configurations of the prototype enable imaging speeds from 70,000 - 312,500 axial scans per second with axial resolutions ranging from ~3 - 9 um, respectively. The prototype instrument was used to image the macula and optic nerve head in the human retina. En face projection visualization of 3D volumetric data sets was performed.

Results: : Dense 3D data sets obtained at high speed show minimal motion artifacts and improved image continuity in the transverse directions. Residual axial motion of the eye can be compensated through correlation methods. Cross sectional images with arbitrary orientation can be extracted from the resulting data sets to investigate structure and pathology. En face projection OCT images can be constructed of different retinal layers. Individual cones can be observed in some regions of the retina without adaptive optics and capillary flow can be resolved using time resolved, volumetric imaging (4D-OCT).

Conclusions: : New CMOS imaging technology enables ultrahigh speed ophthalmic OCT imaging systems with speeds almost an order of magnitude faster than current commercial instruments. The resulting 3D data sets provide continuous and high resolution visualization of the retina, which promises to improve en face visualization, reduce eye motion artifacts and enable time resolved volumetric imaging.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • optic disc