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OCTA represents next step in imaging technology
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OCT uses a relatively long wavelength near infrared light to create a three-dimensional high-resolution cross-sectional image of tissue. The light collected to create the images is reflected or backscattered from the tissue. OCT can image both transparent and opaque tissue and routinely penetrate 500 µm to as much as 1,000 µm into tissue. A typical OCT device used in an ophthalmology practice today has a resolution in the 10-µm range. Thus, a single cell such as a retinal ganglion cell, photoreceptor, retinal pigment epithelial cell or corneal epithelial/keratocyte/endothelial cell can be imaged.
This technology, provided to ophthalmologists primarily by Zeiss, Heidelberg, Topcon and Optovue has revolutionized our diagnostic capability. Nearly every ophthalmology practice in the U.S. utilizes OCT on a daily basis in the clinic and even in the operating room for femtosecond laser-assisted cataract surgery. Now we have even more exciting advances coming to enhance our diagnostic ability.
Newer technologies will allow resolution down to 1 µm, allowing us to resolve intracellular structures such as cell nuclei and other organelles. In addition, OCT angiography (OCTA), as discussed in the accompanying cover story, promises to allow us to evaluate microvascular abnormalities in the retina and decrease the need for fluorescein angiography. This will be a welcome advance, as no patient or doctor enjoys the morbidity and potential risks of intravenous injection of fluorescein dye. In addition, current methods of angiography are more time-consuming.
As OCT technology advances, we are approaching an era in which we can nearly duplicate in vivo the accuracy of a pathologist’s examination of an excisional biopsy-obtained tissue sample. On top of the tremendous clinical diagnostic benefits, this new OCTA technology will generate great learning and advance our understanding of many disease processes. As with standard OCT, OCTA will first be deployed by the retina specialist, but before long, it will find its way into many comprehensive ophthalmology practices.
Disclosure: Lindstrom reports no relevant financial disclosures.