Optic disc in the picture: novel imaging techniques

Abstract

Abstract Purpose Advances in light sources and detection technologies enabled a paradigm shift in retinal OCT imaging performance. ‘Snap‐shot OCT’ enabling isotropic sampling over 512x512x1024 voxels with 600 frames/second in less than a second is now possible. Methods The resolution advantage in conjunction with full volumetric sampling has enabled the development of more informative indices of axonal damage in glaucoma compared with measurements of RNFL thickness and cup to disc ratio provided by other devices. A novel mapping method was developed, the three‐dimensional minimal distance (3D‐MDM) as the optical correlate of true retinal nerve fiber layer thickness around the optic nerve head region. In a preliminary study relation between the cross‐sectional areas of the retinal nerve fiber layer and the optic nerve was found to be a sensitive measure of axon loss. Results In addition to all the major layers of the retina, the entire choroid down to the lamina cribrosa and sclera can now be visualized. This enables unprecedented information about choroidal vasculature without any contrast agents, choroidal thickness and will enable quantification of choroidal blood flow in the near future. Furthermore this technique allows tissue to be imaged in vitro with an image resolution better than 1‐2 µm, allowing to image single cells and detect pre‐apoptotic signatures using OCT. RGC‐5 cells were imaged using a sampling rate 1024x512x1024 voxel at 800 nm central wavelength and a bandwidth of 230 nm, enabling the detection of optical signatures at different pre‐stages of programmed cell death. Conclusion Significantly increased OCT imaging speed and tissue penetration might enable novel insights and diagnostic opportunities in the diagnosis and therapy monitoring of glaucoma. Commercial interest