Biology subjects

Rubinoff, I.

Publications and source records attributed to Rubinoff, I..

4 recordsLinked to original sources

bioRxiv2021

Balanced-detection visible-light optical coherence tomography

Increases in speed and sensitivity enabled rapid clinical adoption of optical coherence tomography (OCT) in ophthalmology. Recently visible-light OCT (vis-OCT) achieved ultrahigh axial resolution, improved tissue contrast, and new functional imaging capabilities, demonstrating the potential to improve clincal care further. However, limited speed and sensitivity caused by the high relative intensity noise (RIN) in supercontinuum lasers impeded the clinical adoption of vis-OCT. To overcome these limitations, we developed balanced-detection vis-OCT (BD-vis-OCT), which uses two calibrated spectrometers to cancel noises common to sample and reference arms, including RIN. We analyzed the RIN to achieve a robust pixel-to-pixel calibration between the two spectrometers and showed that BD-vis-OCT enhanced system sensitivity by up to 22.2 dB. We imaged healthy volunteers at an A-line rate of 125 kHz and a field-of-view as large as 10 mm x 4 mm. We found that BD-vis-OCT revealed retinal anatomical features previously obscured by the noise floor.

bioengineering↗

bioRxiv2021

Adaptive spectroscopic visible-light optical coherence tomography for human retinal oximetry

Alterations in the retinal oxygen saturation (sO2) and oxygen consumption are associated with nearly all blinding diseases. A technology that can accurately measure retinal sO2 has the potential to improve ophthalmology care significantly. Recently, visible-light optical coherence tomography (vis-OCT) showed great promise for noninvasive, depth-resolved measurement of retinal sO2 as well as ultra-high resolution anatomical imaging. We discovered that spectral contaminants (SC), if not correctly removed, could lead to incorrect vis-OCT sO2 measurements. There are two main types of SCs associated with vis-OCT systems and eye conditions, respectively. Their negative influence on sO2 accuracy is amplified in human eyes due to stringent laser power requirements, eye motions, and varying eye anatomies. We developed an adaptive spectroscopic vis-OCT (Ads-vis-OCT) method to iteratively remove both types of SCs. We validated Ads-vis-OCT in ex vivo bovine blood samples against a blood-gas analyzer. We further validated Ads-vis-OCT in 125 unique retinal vessels from 18 healthy subjects against pulse-oximeter readings, setting the stage for clinical adoption of vis-OCT.

bioengineering↗

bioRxiv2021

In Vivo Sublayer Analysis Of Human Retinal Inner Plexiform Layer Obtained By Visible-Light Optical Coherence Tomography

PurposeGrowing evidence suggests, in glaucoma, the dendritic degeneration of subpopulation of the retinal ganglion cells (RGCs) may precede RGCs soma death. Since different RGCs synapse in different IPL sublayers, visualization of the lamellar structure of the IPL could enable both clinical and fundamental advances in glaucoma understanding and management. In this pilot study, we investigated whether visible-light optical coherence tomography (vis-OCT) could detect the difference in the inner plexiform layer (IPL) sublayers thicknesses between small cohorts of healthy and glaucomatous subjects. MethodWe investigated vis-OCT retinal images from nine healthy and five glaucomatous subjects. Four of the healthy subjects were scanned three times each in two separate visits, and five healthy and five glaucoma subjects were scanned three times during a single visit. Raster speckle-reduction scans (3 by 3 by 1.2 mm^3: horizontal; vertical; axial directions with 8192x8x1024 samplings, respectively) of the superior macular were acquired. IPL sublayers were then manually segmented using averaged A-line profiles. ResultsThe mean ages of glaucoma and healthy subjects are 59.6 +/- 13.4 and 45.4 +/- 14.4 years (p =0.02, Wilcoxon rank-sum test), respectively. The visual field mean deviation (MD) are -26.4 to -7.7 dB in glaucoma patient and -1.6 to 1.1 dB in healthy subjects (p =0.002). The mean circumpapillary retinal nerve fiber layer (RNFL) thicknesses are 59.6 +/- 9.1 m in glaucoma and 99.2 +/- 16.2 m in healthy subjects (p=0.004). Median coefficients of variation (CVs) of intra-session repeatability for the entire IPL and three sublayers are 3.1%, 5.6%, 6.9%, and 5.6% in healthy subjects and 1.8%, 6.0%, 7.7%, and 6.2% in glaucoma patients, respectively. The mean entire IPL thicknesses are 36.2 +/- 1.5 m in glaucomatous and 40.1 +/- 1.7 micrometer in healthy eyes (p=0.003, Mixed-effects model). We found that the middle sublayer thickness was responsible for the majority of the difference (14.2 +/- 1.8 m in glaucomatous and 17.5 +/- 1.4 in healthy eyes, p<0.01). ConclusionsIPL sublayer analysis revealed that the middle sublayer could be responsible for the majority of IPL thinning in glaucoma. Vis-OCT quantified IPL sublayers with good repeatability in both glaucoma and healthy subjects. Visualization of the IPL sublayers may enable the investigation of lamella-specific changes in the IPL in glaucoma and may help elucidate the response of different types of RGCs to the disease.

bioengineering↗

bioRxiv2020

Intrinsic spectrally-dependent background in spectroscopic visible-light optical coherence tomography

Visible-light optical coherence tomography (vis-OCT) enabled new spectroscopic applications, such as retinal oximetry, as a result of increased optical absorption and scattering contacts in biological tissue and improved axial resolution. Besides extracting tissue properties from back-scattered light, spectroscopic analyses must consider spectral alterations induced by image reconstruction itself. We investigated an intrinsic spectral bias in the background noise floor, which is hereby referred to as the spectrally-dependent background (SDBG). We developed an analytical model to predict the SDBG-induced bias and validated this model using numerically simulated and experimentally acquired data. We found that SDBG systemically altered the measured spectra of blood in human retinal vessels in vis-OCT, as compared to literature data. We provided solutions to quantify and compensate for SDBG in retinal oximetry. This work is particularly significant for clinical applications of vis-OCT.

bioengineering↗