The treatment of macular diseases requires frequent monitoring by optical coherence tomography (OCT). Home monitoring would reduce the burden of frequent clinical visits and increase therapy adherence. In a pilot study with 47 patients having different macular diseases we tested a proprietary self-examination low-cost full-field OCT (SELFF-OCT). For comparison, scans with a standard clinical spectral domain OCT were taken. Data was graded by a reading center. Patients were able to successfully acquire images that were clinically gradable for 85% of the included eyes. The sensitivity and specificity for an anti-VEGF treatment decision based on the SELFF-OCT was 0.94 and 0.95, respectively.
Off-axis full-field OCT is intended to enable cost-effective imaging of the retina for home diagnosis.
Different to common FD-OCT systems, the lateral field of view is acquired in a single shot and the
different axial layers are acquired sequentially. During acquisition, motion of the eye results in
motion artifacts and misaligned layers. We present a method to track the axial and lateral position of
the retina by analyzing the angle and divergence of the backscattered light with a lateral precision of
3.6 µm and an axial precision of 29 µm. This information can be used to correct motion induced
errors.
Aberration-corrected imaging of human photoreceptor cells, whether hardware or software based, presently requires a complex and often expensive setup. Here, we demonstrate a simple and inexpensive off-axis full-field time-domain optical coherence tomography approach to acquire volumetric data of in vivo human retina. Full volumetric, laterally phase stable data are recorded. The lateral phase stability allows computational aberration correction, which enables us to visualize single photoreceptor cells. In addition, our approach is able to correct large aberrations and is thus feasible for the numerical correction of ametropia in post processing. Our implementation of full-field OCT combines a low technical complexity with the possibility to use the phase of the recorded light for computational image correction.
Time domain OCT measures the interference between sample and reference radiation as a function of the reference arm length. In full-field-OCT (FF-OCT) a camera is used instead of a scanned beam for a parallel detection of the interference pattern and thus acquiring a complete en face image. Because multiple images have to be acquired to resolve the phase ambiguity, this method is prone to motion artifacts.
We present a novel motion-insensitive approach to FF-OCT. Spatially coherent illumination and an off-axis reference beam is used to introduce path-length differences between reference and sample light in neighboring pixels. This spatial carrier frequency replaces the temporal carrier frequency in scanned TD-OCT.
The setup is based on a Mach-Zehnder interferometer with a super-luminescent diode and a CMOS area camera. The Sensitivity of the system was determined to be 75 dB. The field of view was 1.42 x 1.42 mm. Each frame had 237x237 lateral channels at an axial resolution of 9 µm in tissue. By step-wise changing the length of the reference arm between the en face scans, volumetric in vivo FF-OCT measurements of the human retina have been acquired within 1.3 s.
OCT with a spatially coherent off-axis reference beam is suitable for in vivo imaging of human retina. The quality of the images is sufficient to discriminate the different tissue layers.
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