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Biomedical subjects

Richard B Rosen

Publications and source records attributed to Richard B Rosen.

14 recordsLinked to original sources
PubMed2006

Combined confocal/en face T-scan-based ultrahigh-resolution optical coherence tomography in vivo retinal imaging.

Combined confocal scanning ophthalmoscopy/en face T-scan-based ultrahigh-resolution optical coherence tomography (OCT) of the human retina in vivo is reported for the first time to our knowledge. The system uses a superluminescent diode-based broadband source, which gives an axial resolution of 3.2 microm in the retina. We demonstrate acquisition of T-scan-based OCT B-scan and simultaneous confocal/C-scan images of the human retina of large lateral size (covering a field of up to 20 degrees ) at a frame rate of 2Hz.

Equipment Design↗
PubMed2006

Imaging the retina by en face optical coherence tomography.

PURPOSE: To present the possibilities of a new system that combines optical coherence tomography (OCT) and confocal ophthalmoscopy, producing en face OCT images in patients with retinal diseases. METHODS: A prototype OCT Ophthalmoscope (OTI, Toronto, Canada) was used to scan patients with retinal conditions. The system uses a super luminescent diode (lambda = 820 nm; Deltalambda = 20 nm) and currently scans at a rate of 2 frames per second. In each frame, the OCT Ophthalmoscope simultaneously produces a transversal OCT scan and a confocal image in the X/Y plane. Both images correspond pixel to pixel. RESULTS: Between January 2002 and August 2003, >800 patients with various retinal diseases were scanned with the OCT Ophthalmoscope. Illustrative cases with regularly seen macular diseases are presented, such as macular hole and central serous retinopathy. CONCLUSION: Current difficulties as well as future possibilities of this new en face OCT ophthalmoscope are discussed. By presenting normal and pathologic transversal OCT images made by a prototype OCT Ophthalmoscope, we show that it can provide information not available using conventional OCT imaging.

Humans↗
PubMed2005

Simultaneous optical coherence tomography--Indocyanine Green dye fluorescence imaging system for investigations of the eye's fundus.

We have developed a dual-channel optical coherence tomography-Indocyanine Green dye (OCT-ICG) fluorescence system based on a previously reported ophthalmic OCT confocal imaging system. The confocal channel is tuned to the fluorescence wavelength range of the ICG, and light from the same optical source is used to generate the OCT image and to excite the ICG fluorescence. The system enables the clinician to visualize simultaneously en face OCT slices and corresponding ICG angiograms of the ocular fundus, displayed side by side. C-scan (constant depth) and B-scan (cross section) images are collected by a fast en face scan (T scan). The pixel-to-pixel correspondence between the OCT and angiography images allows the user to capture OCT B scans precisely at selected points on the ICG confocal images.

Algorithms↗
PubMed2004

Sequential optical coherence tomography and confocal imaging.

We report a system capable of sequentially acquiring two en-face images of different depth resolutions. The two images are generated by use of different principles, optical coherence tomography (OCT) and confocal microscopy, and have depth resolutions, at present, of better than 20 microm and over 0.12 mm, respectively. The lower-depth-resolution image is ideal for target positioning before collection of stacks of en-face OCT images. Switching between the two types of image by flipping an opaque screen in the reference arm, coupled with self-adjusting gain operation of avalanche photodiodes in the receiver. We illustrate the usefulness of the system by imaging a leaf and an optic nerve in vivo.

Equipment Design↗
PubMed2004

NIR laser tissue welding of in vitro porcine cornea and sclera tissue.

BACKGROUND AND OBJECTIVE: The objective of this study was to test the hypothesis that an near infrared (NIR) laser system (1,455 nm) in combination with a motorized translational stage to control the position and speed of the laser beam and a shutter to control the laser exposure to the tissue being welded could be used to successfully weld ocular tissues. STUDY DESIGN/MATERIALS AND METHODS: Seventy-five porcine corneas and 23 porcine scleral tissues were welded in vitro in this study. The welded tissues were examined using histopathology and tensile strength analysis. Eight different welding conditions were analyzed for porcine cornea and one for sclera tissues. The tensile strength of the welded groups was compared to a sutured cornea control group. RESULTS: The NIR laser welding system provides strong, full thickness welds and does not require the use of extrinsic dyes, chromophores, or solders. Mean weld strengths of 0.15-0.45 kg/cm(2) were obtained for the cornea and 1.01 kg/cm(2) for sclera welds. The native H(2)O in the ocular tissue serves as an absorber of the 1,455 nm radiation and helps to induce the welds. CONCLUSIONS: We conclude that an NIR laser system using an optimal laser radiation wavelength of 1,455 nm can effectively weld cornea and sclera tissue and that this laser tissue welding (LTW) methodology typically causes minimal disruption of tissue, and thus, avoids opacities and irregularities in the tissue which may result in decreased visual acuity. The optimization of a laser welding system that leads to a strong full thickness tissue bond without tissue destruction, an instant seal that promotes wound healing, and the absence of a continued presence of a foreign substance like a suture, is of considerable importance to the ophthalmology medical community. This need is especially apparent with respect to corneal transplantation and fixing the position of corneal flaps in Laser-Assisted In Situ Keratomileusis (LASIK), a laser procedure used to permanently change the shape of the cornea.

Animals↗
PubMed2004

A 3-dimensional ultrasound C-scan imaging technique for optic nerve measurements.

PURPOSE: To evaluate the use of 3-dimensional ultrasound C-scan imaging for optic nerve diameter measurements. DESIGN: Prospective observational case series. PARTICIPANTS: Thirty-eight normal eyes of 32 healthy adults. METHODS: Coronal C-scans of 38 normal optic nerves were imaged 3 mm behind the globe. MAIN OUTCOME MEASURES: Optic nerve sheath diameter (ONSD) and optic nerve diameter (OND). RESULTS: Mean ONSD was 4.8 mm (range: 3.9-5.9; SD 0.6), whereas mean optic OND was 1.9 mm (range: 1.8-2.1; SD 0.1). Mean ONSDs were 4.9 mm (male), 4.5 mm (female), 5.0 mm (subjects younger than 50 years), and 4.6 mm (subjects 50 and older). CONCLUSION: Coronal C-scans generated from 3-dimensional ultrasound can be used to measure the optic nerve diameters in adult eyes.

Adult↗
PubMed2003

Native fluorescence and excitation spectroscopic changes in Bacillus subtilis and Staphylococcus aureus bacteria subjected to conditions of starvation.

Fluorescence emission and excitation spectra were measured over a 7-day period for Bacillus subtilis (Bs), a spore-forming, and Staphylococcus aureus (Sa), a nonspore-forming bacteria subjected to conditions of starvation. Initially, the Bs fluorescence was predominantly due to the amino acid tryptophan. Later, a fluorescence band with an emission peak at 410 nm and excitation peak at 345 m, from dipicolinic acid, appeared. Dipicolinic acid is produced during spore formation and serves as a spectral signature for detection of spores. The intensity of the 410-nm band continued to increase over the next 3 days. The Sa fluorescence was predominantly from tryptophan and did not change over time. In 6 of the 17 Bs specimens studied, an additional band appeared with a weak emission peak at 460 cm and excitation peaks at 250, 270, and 400 nm. The addition of beta-hydroxybutyric acid to the Bs or the Sa cultures resulted in a two-order of magnitude increase in the 460-nm emission. The addition of Fe2+ quenched the 460 emission, indicating that a source of the 460-nm emission was a siderophore produced by the bacteria. We demonstrate that optical spectroscopy-based instrumentation can detect bacterial spores in real time.

3-Hydroxybutyric Acid↗
PubMed2003

Detection of glutamate in the eye by Raman spectroscopy.

Raman spectroscopy is used to detect glutamate in the eye. Glutamate, a by-product of nerve cell death, is an indicator of glaucoma and diabetic retinopathy. The Raman spectra of ex vivo whole porcine eyes and individual components (lens, cornea, vitreous) are measured and characterized. Monosodium glutamate is injected into the eyes to simulate disease conditions, and the contribution to the Raman spectrum due to the presence of glutamate is identified. The Raman spectra from the native eye is dominated by vibrational modes from proteins in the lens. An optical system is designed to optimize collection of signal from the vitreous, where the glutamate is located, and reduce the Raman from the lens. Two vibrational fingerprints of monosodium glutamate are detected at 1369 and 1422 cm(-1), although the concentrations are much above physiological concentrations.

Animals↗
PubMedDate not supplied

Retinal blood flow in the normal human eye using the canon laser blood flowmeter.

PURPOSE: To establish a retinal blood flow database in normal human eyes using the Canon Laser Blood Flowmeter (CLBF). METHOD: Fourteen healthy subjects (7 males, 7 females) between the ages of 24 and 33 underwent birectional laser Doppler velocimetry (BLDV) in one eye using the CLBF. Measurements consisting of blood vessel diameter (D) in micrometers, velocity (V) in millimeters per second, and flow (F) in microliters per minute were recorded at sites along the major retinal veins. Four to six veins were measured in each eye. Total volumetric blood flow was calculated as the sum of the venous flow rates in the major veins. RESULTS: Total retinal blood flow could be reliably determined on 5 of the subjects (1 male, 4 females). Venous blood vessel diameter ranged from 84 to 177 microm. The correlations between D and F, as well as D and V were found to be significant. Specifically, the correlation coefficient between D and F was 0.885 (p < or = 0.001), while the log-log regression coefficient was 3.35 +/- 0.23 (p < or = 0.001). The correlation coefficient between D and V was 0.694 (p < or = 0.001), while the log-log regression coefficient was 1.43 +/- 0.27 (p < or = 0.001). Total venous blood flow showed a mean of 64.9 +/- (SD) 12.8 microl/min (range: 50.9-80.6 microl/min). Venous blood flow averaged 44.1 +/- 4.5 microl/min temporally and 20.8 +/- 9.2 microl/min nasally, showing a temporal retinal blood flow approximately twice that of the nasal retina (p < 0.001). On the other hand, venous blood flow averaged 30.6 +/- 9.8 microl/min superiorly and 34.3 +/- 8.0 microl/min inferiorly. These values showed no statistical difference. CONCLUSION: The average total retinal blood flow in 5 healthy subjects using the CLBF was 64.9 +/- 12.8 microl/min. Venous blood flow at the temporal retina was about twice that of the nasal retina, whereas flow at the superior and inferior retina showed no statistical difference. Our findings are comparable with studies done using a different BLDV system.

Adult↗
PubMedDate not supplied

Surface rendering of 3D ultrasound images in ophthalmology.

Surface rendering of three-dimensional ultrasound images is a novel way of imaging ophthalmic pathologies in vivo. The authors have evaluated surface rendering of three-dimensional ultrasound images in selected cases of opthalmic disease.

Diagnostic Techniques, Ophthalmological↗
PubMedDate not supplied

Wide-field handheld high frequency ultrasonography using a variable high frequency ultrasound system.

Wide-field handheld high frequency ultrasonography using a variable high frequency ultrasound system is an imaging modality in the frequency range of 35 to 50 MHz. Using a water bath immersion technique, high-resolution digital movies obtained from a variety of anterior segment ocular conditions were particularly helpful in establishing the diagnosis in each case. Images taken with the wide-field limbus-to-limbus mode provided a comprehensive picture of large and extensive lesions, whereas the focal mode was for small to medium lesions or specific areas of interest.

Anterior Eye Segment↗
PubMedDate not supplied

Optic nerve measurements by 3D ultrasound-based coronal "C-scan" imaging.

Twenty-three normal eyes were examined with the Intensity Profiling technique of 3D I-Scan and 52 normal eyes with the Automated technique of OTI-Scan 1000 ultrasound systems (Ophthalmic Technologies Inc., Toronto, Ontario, Canada). With the eye looking straight, the probe was applied on the temporal sclera. Scanning generated 3D image files. Coronal optic nerve measurements were obtained 3 mm behind the globe. The mean optic nerve sheath diameter was 4.8 mm (standard deviation = 0.6; range, 3.9 to 5.9 mm) with the Intensity Profiling technique, and 5.4 mm (standard deviation = 0.4; range, 4.4 to 6.0 mm) with the Automated technique. 3D ultrasound imaging can be used to obtain optic nerve measurements in vivo. Both the Intensity Profiling and the Automated techniques yielded measurements similar to current magnetic resonance imaging and computed tomography scan reports. Coronal "C-scan" sectioning can be used as a screening tool to measure optic nerve diameter prior to magnetic resonance imaging or computed tomography.

Adult↗