Recently, dramatic advances in OCT technology have enabled OCT imaging with a ~15-times to 50-times increase in imaging speed over standard-resolution OCT systems and ~100-times increase over UHR OCT systems. Imaging speeds in conventional UHR OCT are slower than those in standard-resolution OCT, so the coverage of the retina is even more restricted. Thus, focal areas of pathology can be missed. 2, 14, 15 Assessment of these areas involves the acquisition of a small set of individual OCT images with a given scan pattern and, therefore, does not provide comprehensive coverage of the retina. Instead, specialized OCT diagnostic protocols were developed to image and assess quantitatively the macula and peripapillary region and optic nerve head. Because standard OCT systems have limited image acquisitions speeds, comprehensive 3D imaging of the retina was not previously possible. The total permissible image acquisition time for any OCT system is limited by subject eye motion, which can cause image artifacts. 9 – 13 Improved axial resolution enables the visualization and measurement of intraretinal layers such as photoreceptor, ganglion cell, plexiform, and nuclear. 5 – 8 Recently, ultrahigh-resolution OCT (UHR OCT) imaging with axial resolutions of ~3 μm has been demonstrated this technique significantly improves the visualization of retinal morphology.
Optical coherence tomography techniques that provide 3-dimensional (3D) information, including fundus images, have also been developed. 1 – 4 A commercial system, the StratusOCT (Carl Zeiss Meditec, Dublin, CA), with an axial resolution of 10 μm has been developed. Over the past 10 years, optical coherence tomography (OCT) has emerged as a new technique that can provide high-resolution cross-sectional images of the retina for identifying, monitoring, and quantitatively assessing diseases of the macula and optic nerve head.
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