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Optically active sec-alcohols, epoxides, and sulfoxides were prepared by one-pot process of a combination of synthesis and enantiomeric resolution through inclusion complexation with an optically active host in a water suspension medium.
Using a local oxidation process with a probe tip of a scanning near-field optical microscope (SNOM), antimony oxide structures with a pattern width of several 100 nm were fabricated on antimony thin films. We also investigated the characteristics of the oxidation process using the transmission mode SNOM. Although slight topographic changes due to oxidation were observed by atomic force microscopy, an increase in transmission due to the phase change of the metal to transparent oxide was observed. The depth of the oxide embedded in the antimony film was estimated from the change of the transmission intensity without destroying the sample. This fabrication method is appropriate for making a prototype of future nano-optical devices and for trimming them in order to optimize their functions on demand.
The effects of the d and l optical isomers of methadone and (S)-(-)- and (R)-(+)- optical isomers of pentobarbital were studied on responding maintained under a multiple fixed-ratio 30-response fixed-interval 5-min schedule of food presentation in rats before, during, and after chronic administration of d- or l- methadone. Acute administration of both isomers of pentobarbital decreased responding more during the fixed-ratio component of the schedule than during the fixed-interval component. S-(-)-pentobarbital was slightly more potent than R-(+)-pentobarbital in decreasing the rate of fixed-ratio responding and the fixed-interval quarter life. Daily administration of d-methadone for four weeks shifted the dose-effect curves for (S)-(-)-pentobarbital to the right for both schedule components; however, (R)-(+)-pentobarbital showed less tendency to shift. Daily administration of l-methadone showed little tendency to shift the dose-effect curve for either pentobarbital isomer. Before chronic treatment, acute administration of l-methadone, decreased rates of both FR and FI responding at much lower doses than d-methadone. Unlike d-methadone, chronic daily l-methadone shifted the l-methadone dose-effect curves to the right during both components of the schedule.
PURPOSE: Evaluation of multifocal IOL (three optical zones). METHODS: Twenty patients were implanted. Main outcome measures were: uncorrected and best corrected distance and near acuity, brigthness acuity test, contrast acuity with differents methods: Pelli-Robson Chart, Gradual System, and spatial visual integration (SVI). RESULTS: Uncorrected visual acuity was restored in 94% of cases. Contrast sensitivity was preserved with the Pelli-Robson chart test but a loss of contrast sensitivity was found with the multifocal IOL with the Gradual system and the SVI in comparison with monofocal IOL. CONCLUSION: Multifocal IOL (three optical zones) allows a good restoration of both near and far visual acuity but a decrease in contrast sensitivity was detected.
Optical Coherence Tomography (OCT) is a recently developed non-invasive technique for obtaining high resolution, cross-sectional images of human tissue. This work investigated the capability of OCT to differentiate the architectural morphology of urologic tissue with the long term aim of using OCT as an adjunct to endoscopic imaging and to improve the efficiency of interventional procedures such as transurethral prostatectomy (TURP). Urologic tissues were taken postmortem, dissected, and imaged using OCT. Microstructure was delineated in different urologic tissues, including the prostatic urethra, prostate, bladder, and ureter, with an axial resolution of 16 +/- 1 microm., higher than any clinically available endoscopic intraluminal imaging technology. The ability of OCT to provide non-contact high resolution imaging of urologic tissue architectural morphology (i.e. optical biopsy), without the need for excisional biopsy, suggests the potential of using OCT to obtain information on tissue microstructure that could only previously be obtained with conventional biopsy.
BACKGROUND AND OBJECTIVES: The first objective of this study was to evaluate the performance of fluorescence spectroscopy for diagnosing pre-cancers in stratified squamous epithelial tissues in vivo using two different probe geometries with (1) overlapping versus (2) non-overlapping illumination and collection areas on the tissue surface. Probe (1) and probe (2) are preferentially sensitive to the fluorescence originating from the tissue surface and sub-surface tissue depths, respectively. The second objective was to design a novel, angled illumination fiber-optic probe to maximally exploit the depth-dependent fluorescence properties of epithelial tissues. STUDY DESIGN/MATERIALS AND METHODS: In the first study, spectra were measured from epithelial pre-cancers and normal tissues in the hamster cheek pouch and analyzed with a non-parametric classification algorithm. In the second study, Monte Carlo modeling was used to simulate fluorescence measurements from an epithelial tissue model with the angled illumination probe. RESULTS: An unbiased classification algorithm based on spectra measured with probes (1) and (2), classified pre-cancerous and normal tissues with 78 and 94% accuracy, respectively. The angled illumination probe design provides the capability to detect fluorescence from a wide range of tissue depths in an epithelial tissue model. CONCLUSIONS: The first study demonstrates that fluorescence originating from sub-surface tissue depths (probe (2)) is more diagnostic than fluorescence originating from the tissue surface (probe (1)) in the hamster cheek pouch model. However in general, it is difficult to know a priori the optimal probe geometry for pre-cancer detection in a particular epithelial tissue model. The angled illumination probe provides the capability to measure tissue fluorescence selectively from different depths within epithelial tissues, thus obviating the need to select a single optimal probe design for the fluorescence-based diagnosis of epithelial pre-cancers.
A 33-year-old woman had thrombotic thrombocytopenic purpura. She developed optic atrophy and bilateral neovascularization of the disk with extensive vitreous hemorrhage that progressed to traction and rhegmatogenous retinal detachment.
Fibers of the accessory optic tract (AOT) terminating in the medial terminal nucleus (MTN) were observed in the mouse by the rapid Golgi method. The AOT fibers, which entered the MTN from its ventromedial aspect, were divided into thick and fine fiber groups, the thick fibers emitting many terminal collaterals of various calibers, and the fine ones generating fine terminal branches. The possibility exists that the retinal neurons sending AOT fibers to the MTN might be heterogeneous in nature.
OBJECTIVE: To objectively define criteria for intracranial optic nerve (ON) size in ON hypoplasia (ONH) on magnetic resonance imaging (MRI) scans. STUDY DESIGN: Intracranial ON sizes from MRI were compared between 46 children with ONH diagnosed by ophthalmoscopy (group 1, isolated ONH, 8 children; and group 2, ONH associated with abnormalities of the hypothalamic-pituitary axis and septum pellucidum, 38 children) and children with multiple pituitary hormone deficiency (group 3, multiple pituitary hormone deficiency, 14 children), isolated growth hormone deficiency (group 4, isolated growth hormone deficiency, 15 children), and idiopathic short stature (group 5, idiopathic short stature, 10 children). Intracranial ON size was determined by the cross-sectional area, calculated as [pi x (1/2) height x (1/2) width]. RESULTS: Groups 1 and 2 had lower intracranial ON size than did groups 3, 4, and 5 (P < .001). No patients in groups 3 through 5 who had MRI after 12 months of age (when 95% adult size of ONs is attained) had ONs <2.9 mm 2 . Visual acuity correlated significantly with ON size (P < .01). CONCLUSIONS: Magnetic resonance imaging of the ONs with cross-sectional area <2.9 mm 2 in a short child more than 12 months of age, with or without hypothalamic-pituitary axis abnormalities, confirms the clinical diagnosis of ONH.
We propose here a conceptual framework for understanding the optic nerve head (ONH) as a biomechanical structure. Basic principles of biomechanical engineering are used to propose a central role for intraocular pressure (IOP)-related stress and strain in the physiology of ONH aging and the pathophysiology of glaucomatous damage. Our paradigm suggests that IOP-related stress and strain (1) are substantial within the load-bearing connective tissues of the ONH even at low levels of IOP and (2) underlie both ONH aging and the two central pathophysiologies of glaucomatous damage--mechanical failure of the connective tissues of the lamina cribrosa, scleral canal wall, and peripapillary sclera, and axonal compromise within the lamina cribrosa by a variety of mechanisms. Modeling the ONH as a biomechanical structure generates a group of testable hypotheses regarding the central mechanisms of glaucomatous damage and provides a logic for classifying the principal components of the susceptibility of an individual ONH to a given level of IOP.
We theoretically evaluate and experimentally verify a novel strategy for spatially resolved analyte mapping over extended remote areas. The approach combines a method for the fabrication of continuous extended-length sensors with optical time-of-flight chemical detection (OTOF-CD). The use of OTOF-CD makes it possible to locate the zones in the fiber where attenuation or fluorescence takes place, to determine the magnitude of these variations, and to relate the magnitude of the variations to the local concentration or concentrations of a single analyte or several analytes. Simulation experiments suggest that OTOF-CD should provide spatial resolution close to its theoretical limit by deconvolution of the returned wave form with all time-dependent experimental variables (laser pulse width, reagent fluorescence lifetime, etc.). The signal-processing technique should be useful for a wide variety of sensors based on absorption, refractive index, or statically and dynamically quenched fluorescence. Experimental results with a model system (a 48-m-long oxygen sensor) compare favorably with those predicted by numerical simulations. Possible experimental difficulties in the realization of these novel sensors are discussed as are ways to overcome them.
The size of the neuroretinal rim area of the disk was measured with the Optic Nerve Head Analyzer in 57 eyes of 57 patients with low-tension glaucoma (LTG), glaucoma simplex (POAG), and pigmentary glaucoma. The visual fields were examined with Program 33 or 31 (30 degrees eccentricity, 6 degrees grid) of the Octopus 201 Perimeter. The mean sensitivity loss per test point in the central field, in the field quadrants, and in the ranges from 0 degrees-10 degrees, 10 degrees-20 degrees, and 20 degrees-30 degrees were calculated with the Delta program. In addition, the mean loss per disturbed point, which gives the mean depth of scotomata, was calculated. In LTG a larger vertical cup/disk ratio (CDR) was found than in POAG for the same amount of total loss. The comparison of eyes with neuroretinal rim areas of equal size revealed that in contrast to POAG and pigmentary glaucoma, eyes with LTG had a smaller mean sensitivity loss; deeper, more localized scotomata; more visual field defects in the lower field in the initial stages; more scotomata in the area up to 20 degrees. The differences between glaucoma with and without high intraocular pressure were found to be most pronounced in the initial stages of the disease. These differences appear to be caused by the varying amounts of vascular pathogenesis involved. Therefore, at least two pathomechanisms have to be considered in glaucoma.
A new fiber-optic oxygen sensor has been developed for use in medical applications. The sensor's viologen indicator becomes strongly absorbent after brief UV stimulation, and then returns to the transparent state. The rate of indicator return to transparency is proportional to the local oxygen concentration. Indicator absorbance is monitored with a red LED and receiving photodiode, and absorbance data are processed by a dedicated cpu. The solid-state sensor system has performance comparable to existing oxygen measurement techniques, and may be applicable for both in vitro and in vivo oxygen measurements.
A new fiber-optic pH sensor system has been developed. The sensor uses an absorbtive indicator compound with a long wave-length absorption peak near 625 nm; change in absorption over the pH range 6.8 to 7.8 is reasonably linear. The sensor is interrogated by a pulsed, red LED. Return light signal is split into short and long wave-length components with a dichroic mirror; the respective signals are detected by photodiodes, and their photocurrents are used to form a ratiometric output signal. In laboratory tests, the sensor system provided resolution of 0.01 pH, accuracy of +/- 0.01 pH, and response time of 30-40 s. Following gamma sterilization, laboratory sensor testing with heparinized human blood yielded excellent agreement (e.g., r = 0.992 for n = 42) with a clinical blood gas analyzer. Excellent sensor performance and low cost, solid-state instrumentation are hallmarks of this sensor-system design.
An anatomical taxonomy for neovascular proliferation of the optic nerve head in patients with proliferative diabetic retinopathy is presented. The technique consists in comparing (A) number of involved quadrants, (B) calibre of vessels, (C) neovascular density, (D) neovascular area, (E) plane of proliferation, and (F) fluorescein angiographic findings. A similar taxonomy is used to describe fibrous tissue proliferation at the disc. With these criteria a series of standard photographs have been utilised in a numerical grading system. This system has proved useful in documenting the natural history and response to photocoagulation therapy for diabetic disc neovascularisation.
PURPOSE: To compare nerve fiber layer thickness (NFLT) in patients with glaucoma measured by two versions of an analysis program utilizing optical coherence tomography (OCT) with reference to the cup-to-disk (C/D) ratio and the mean deviation (MD) score of a static visual field test. METHODS: Twenty-four eyes from 24 glaucoma patients were enrolled. The NFLT was measured by OCT along a circle around the disk with the circle diameter being 1.5 times that of the disk itself. The NFLTs evaluated by the two versions A4.01 and A6.01 were compared with respect to the C/D ratio and MD score. RESULTS: The mean NFLTs evaluated by version A6.01 were 61.2% greater than those evaluated by version A4.01 (p < 0.001). The NFLTs in all quadrants evaluated by A6.01 were also greater than those evaluated by A4.01. Both A6.01 and A4.01 showed a significant correlation with the C/D ratio and MD score. Although A6.01 showed a better correlation with the C/D ratio than A4.01, both A4.01 and A6.01 showed similarly good correlations with MD. CONCLUSION: The NFLTs evaluated by the two versions differed significantly with regard to some parameters. These results should be taken into account in evaluating NFLTs when utilizing OCT.
PURPOSE: To develop an eye-motion-tracking optical coherence tomographic (OCT) method and assess its effect on image registration and nerve fiber layer (NFL) thickness measurement reproducibility. METHODS: A system capable of tracking common fundus features based on reflectance changes was integrated into a commercial OCT unit (OCT II; Carl Zeiss Meditec, Inc., Dublin, CA) and tested on healthy subjects and patients with glaucoma. Twenty successive peripapillary NFL scans were obtained with tracking and 20 without tracking, for 40 images in each session for each eye. Subjects participated in one session on three different days. Composite OCT scans and composite fundus images were generated for assessment of eye tracking. NFL thickness measurement reproducibility was also assessed. RESULTS: Seven healthy and nine glaucomatous eyes of 16 subjects were recruited. A qualitative assessment of composite OCT scans and composite fundus images showed little motion artifact or blurring along edges and blood vessels during tracking; however, those structures were less clearly defined when tracking was disengaged. There was no significant reproducibility difference with and without tracking in both intra- and intersession NFL measurement SD calculations in any location. The mean retinal pixel SD was significantly smaller with tracking than without (490.9 +/- 19.3 microm vs. 506.4 +/- 31.8 microm, P = 0.005, paired t-test). CONCLUSIONS: A retinal-tracking system was successfully developed and integrated into a commercial OCT unit. Tracking OCT improved the consistency of scan registration, but did not influence NFL thickness measurement reproducibility in this small sample study.
The purpose of the case study was to determine an optimal method for monitoring the condition of the optic nerve disk (OND) and for precising the OND peculiarities in patients with normal pressure glaucoma (NPG). A comparison of the OND calculated parameters obtained for 16 patients (31 eyes), both by the "Rodenstock" scanning laser ophthalmoscope (SLO) and by HRT-II, revealed that the OND parameters calculation preformed by HRT-II was more informative, diversified and automated, which essentially cuts the procedure time. We examined, by HRT-II, a group of 31 patients (61 eyes), comprising patients with high pressure glaucoma (HPG), with suspected NPG and with moderate-pressure glaucoma (MPG) and a group of controls with moderate arterial hypertension. A comparison of OND areas' distributions of three groups (NPG group, MPG group and HPG group) showed that the majority of disks had an area ranging from 2.0 to 2.6 mm2 in the NPG, the same index ranged from 1.8 to 2.2 mm2 in the MPG group, and in the HPG group the disks were evenly distributed by area virtually in all ranks. The OND area was on the average less (2.13 mm2) in an impaired autoregulation versus the group without any symptoms of peripheral vasospasm (2.49 mm2). According to our findings, a higher OND size contributes to aggravating glaucoma at a lower intraocular pressure (IOP). It is noteworthy, that more pronounced changes are observed on the side with a bigger OND area in absence of any other risk factors, e.g. neuro-ophthalmic pathology or stenosis of the main cerebral arteries.