Optical coherence tomography (OCT) has had significant success in the field of ophthalmology, where it is essential for both screening and diagnosis. Clinical ophthalmic OCT systems are primarily used as table-top instruments that requires the subject to align with the chinrest and be operated by qualified personnel. In order to perform OCT imaging on bedridden patients or on babies, a handheld model is essential. In handheld devices, eye movements and probe movements cause artifacts while recording OCT images, making interpretation and registration more difficult. As a result, there is a need for an OCT scanner with an automatic real-time eye-tracking system and a correction mechanism to compensate for such movements. This work aims at developing a scanner head employing a cutting-edge stereo edge camera equipped with an inertial measurement unit (IMU) for detecting rotations and motions with six degrees of freedom. In this work, an Intel RealSense D435i depth camera-based eye tracking is performed. A python-based code was developed to image the eye continuously, detect face landmarks with media pipe, process the eye features in each frame, identify the iris in each frame and a circle is marked over the iris which would move along with the iris. The algorithm is tested on various scenarios of face angle and head motion. The eye movement identification and tracking capability of the developed algorithm and its performance results are presented in this study.
Optical Coherence Tomography (OCT) is a non-invasive optical imaging technique capable of producing high-resolution cross-sectional 2D and 3D images of non-homogeneous samples, such as biological tissue. It is a gold standard in retinal imaging. In this work, an analytical model of the retina is developed to investigate the scientific principles of the OCT system. The Michelson interferometer configuration is modeled in Matlab using standard interferometric equations. A broadband light source centered at 840 nm with a spectral width of 46 nm with a Gaussian profile is modeled. The retina is simulated with a few layers of refractive indices based on the values reported so far in the literature. The final interferogram based on the above model and sample is obtained and analyzed in both time domain (TD) and spectral domain (SD) OCT configuration and an A-scan is generated. The A-scan obtained clearly shows the boundary between the layers with intensity dependent on the change in refractive index between layers and the amount of light available at each layer.
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