Author: James G. Fujimoto, Ph.D.
Elihu Thomson Professor of Electrical Engineering, Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology, Cambridge, MA
Recent advances are continuing to increase imaging speed and performance for swept source OCT (SS-OCT). SS-OCT can operate at long 1050 nm wavelengths which have reduced attenuation and increased exposures compared with 840 nm SD-OCT technology. In addition, SS-OCT speeds can be substantially faster than SD-OCT. Therefore SS-OCT is well suited for OCT angiography (OCTA) imaging protocols which require repeated scanning of the same retinal position to detect blood flow. This presentation describes wide field SS-OCTA, utilizing high speed to achieve wide retinal coverage, and time resolve OCTA, utilizing high speed to achieve time resolution. Wide field OCTA can be performed by commercial instruments using standard speeds and eye tracking. Wide field OCTA and can assess capillary non-perfusion, a potentially important marker in diabetes and diabetic retinopathy. At the same time, wide field OCTA is challenging because artifacts can result from low OCT signals. We describe methods to detect and correct for artifacts in wide field OCTA as well as applications to diabetic retinopathy. Time resolved OCTA requires ultrahigh imaging speeds. Recent improvements in vertical cavity surface emitting swept laser (VCSEL) technologies, combined with increases in safe retinal exposures enable increases in imaging speeds from 400,000 A-scans/second to 800,000 A-scans/second in research instruments, up to 8x faster than current commercial technology. These ultrahigh speeds enable time resolved OCTA where rapidly repeated volumes are acquired to sample flow changes with cardiac cycle. Time resolved OCTA using very short interscan times increases differentiation of flow impairment and can resolve changes associated with systole and diastole. We present applications in diabetic retinopathy and age related macular degeneration which suggest the potential for future SS-OCT assessment of retinal and choroicapillaris structure and flow impairment.
Disclosures: Royalties from intellectual property owned by MIT and licensed to Optovue. Equity in Optovue. Research support from Topcon.