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At least 343 records · Page 19Linked to original sources
PubMed1977

Turbulence measurement by the pulse luminescence method using a nitrogen pulse laser.

In order to visualize and measure with ease the velocity distribution and diffusion of turbulent flow, the pulse luminescence method was investigated. Turbulence intensity was obtained from the turbulent diffusion patterns by Taylor's diffusion theory. Apparatus was developed for easier measurement. A nitrogen pulse laser was used for instantaneous, high-power excitation. With the use of a night vision scope a bright image was recorded by a TV camera and video tape recorder. The optimum concentration of LC-G1A luminescent particles was about 0-05% wt for the measurement. High fidelity of the particles as an indicator of the fluid velocity was confirmed. It was demonstrated that the turbulence intensity could be visualized and measured quantitatively by the pulse luminescence method.

Lasers↗
PubMed2005

A comparison of therapeutic regimens containing moxifloxacin 0.5% ophthalmic solution and gatifloxacin 0.3% ophthalmic solution for surgical prophylaxis in patients undergoing LASIK or LASEK.

The purpose of these two studies was to compare the safety and tolerability of moxifloxacin 0.5% ophthalmic solution and gatifloxacin 0.3% ophthalmic solution for use with laser-assisted in situ keratomileusis (LASIK) and laser-assisted subepithelial keratomileusis (LASEK) patients. Treatment with the two antibiotic regimens was randomly assigned to fellow eyes of each patient. The LASIK study showed no difference between the two therapies in terms of visual acuity, pupil size, SPK, edema, haze, day- and nighttime glare, halos, clarity of day or night vision, and dry eye symptoms up to 1 week after surgery. Patients reported no preference between the two antibiotics on the basis of ease of use, irritation, redness, itching, gritty, sandy or scratchy feeling, speed of recovery, overall vision, or overall comfort up to 7 days after LASIK surgery. Corneal healing after LASEK surgery was equivalent for the antibiotic regimens containing moxifloxacin 0.5% ophthalmic solution and gatifloxacin 0.3% ophthalmic solution. When comparing safety and tolerability, these findings suggest an equivalent role for these fluoroquinolone antibiotics in surgical prophylaxis.

Adult↗
PubMed2005

The concentration of free holo-retinol binding protein is higher in vitamin A-sufficient than in deficient Nepalese women in late pregnancy.

Free holo-retinol binding protein (RBP) [i.e., unbound to transthyretin (TTR)] plays a role in transporting vitamin A across the placenta during pregnancy. In a cross-sectional study of clinically healthy urban women, we assessed the association among clinical and biochemical factors on estimated concentrations of free holo-RBP during the last trimester of pregnancy. Serum samples obtained from a subsample of women (n = 259), who had participated in the Night Vision Threshold Test study in Nepal, were analyzed for determinations of retinol by HPLC, and RBP, TTR, and alpha-1 acid glycoprotein by radial immunodiffusion. Free holo-RBP concentrations were calculated using dissociation constants for free holo- and apo-RBP. Among these women, 30% were vitamin A deficient based on either the RBP:TTR index < or = 0.36 or serum retinol < 1.05 micromol/L. Using stepwise regression analyses, the RBP:TTR index explained 75% of the variance in free holo-RBP concentrations, whereas retinol explained only 14%. Women were classified as vitamin A sufficient (n = 185) or deficient (n = 74) using the RBP:TTR index and were stratified into 3 gestational groups (I: 24-28 wk, II: 29-33 wk, III: >33 wk). Concentrations of free holo-RBP were higher in vitamin A-sufficient women than in vitamin A-deficient women (mean +/- SEM, 48.1 +/- 1.2 vs. 27.6 +/- 0.8 nmol/L; P < 0.001), and in a 3 x 2 factorial analysis, the interaction between gestational group and vitamin A status was significant. These results demonstrate that the RBP:TTR index is a useful proxy for free holo-RBP concentration and that vitamin A status affects its distribution.

Adult↗
PubMed2003

Comparison of reverse-geometry lens designs for overnight orthokeratology.

PURPOSE: The efficacy of overnight wear of four types of reverse-geometry lenses was compared. The length of time needed to achieve correction and any adverse events that occurred during the course of the study were recorded. METHODS: In this prospective, randomized study, 60 subjects (18 to 35 years old) with refractive error between -1.00 to -4.00 D (cyl </= -1.50) wore reverse-geometry lenses overnight only. All subjects were assigned a Rinehart Reeves lens in one eye, and subsets of 20 subjects were randomly assigned a Mountford BE, DreimLens, or Contex D Series 4 lens for the contralateral eye. Visits included baseline, dispensing, 1 day, 1 week, and 1 month. Biomicroscopy, unaided visual acuity, subjective refraction, best-corrected visual acuity at high and low contrast and high and low illumination, corneal topography, and subjective rating data were collected. RESULTS: Forty-six subjects completed the study. At 1 month, there were no significant differences between lens types in their effect on unaided visual acuity, subjective sphere, subjective cylinder, best-corrected visual acuity at high and low contrast at high illumination and low contrast at low illumination, apical corneal radius, corneal eccentricity, and subjective ratings. Between 1 week and 1 month, there was a significant improvement in subjective ratings of quality of day and night vision (p < 0.05) but no significant change in the objective measures. No significant ocular adverse events were observed during the trial. CONCLUSIONS: The lens types tested were all similarly effective in the reduction of myopic refractive error. Subjective ratings continued to improve after objective measures stabilized at 1 week. Overnight lens wear proceeded for 1 month without significant adverse reactions.

Adult↗
PubMed2001

Effectiveness and safety of brimonidine as adjunctive therapy for patients with elevated intraocular pressure in a large, open-label community trial.

PURPOSE: To determine the effectiveness and safety of brimonidine when used in combination with one or more glaucoma medications in patients with glaucoma or ocular hypertension. METHODS: Post hoc analysis of a multicenter, 2-month, open-label, prospective, clinical trial in which 2,335 patients received brimonidine as monotherapy, replacement therapy, or combination therapy. Patients who received brimonidine as combination therapy (n = 554) were examined in the current analysis. Efficacy was determined by the reduction in intraocular pressure (IOP) from baseline before the addition of brimonidine. Safety and tolerability parameters included adverse events and quality-of-life measures (e.g., ocular comfort, energy level, breathing ability, night vision). RESULTS: Addition of brimonidine to preexisting regimens resulted in an overall mean additional reduction in IOP of 17.9% (4.26 mm Hg) at month 2 (P < 0.001). Significant additional IOP lowering was provided by brimonidine in combination with each preexisting regimen evaluated (P < or = 0.061). When brimonidine was added to monotherapy with a nonselective beta-blocker, the mean additional IOP reduction was 15.5% (3.61 mm Hg, P < 0.001). Addition of brimonidine to latanoprost monotherapy provided a 32.2% (5.89 mm Hg) mean additional IOP reduction (P < 0.001). Addition of brimonidine to combination regimens that included latanoprost provided additional mean decreases in LOP ranging from 15.5% (3.63 mm Hg, P < 0.002) to 20.1% (6.62 mm Hg, P < 0.001). All quality-of-life parameters remained high or improved during the study. Mild to moderate adverse events were reported in 5.23% of patients (29 of 552); 98.1% of physicians rated brimonidine adjunctive therapy as good or excellent. CONCLUSIONS: Brimonidine, when added to existing glaucoma regimens, safely and effectively lowered IOP in this community-based trial.

Adrenergic alpha-Agonists↗
PubMed1980

Continual monitoring of fluorescein angiography.

A system has been developed which enables continuous monitoring and recording of circulating fluorescein in the retinal blood vessels. This is achieved with minimal modification of a Zeiss fundus camera. A night vision television camera (lkegami) is used with illumination provided by the standard observation light of the fundus camera. This method offers advantages over standard fluorescein angiography in patient comfort, information obtained and the immediate evaluation of the fluorescein angiograms being available.

Fluorescein Angiography↗
PubMed1986

Zinc metabolism in alcoholic liver disease.

Alterations in zinc metabolism or zinc deficiency frequently occur in patients with alcoholic liver disease. Potential manifestations of zinc deficiency include skin lesions, hypogonadism, impaired night vision, impaired immune function, anorexia, altered protein metabolism, diarrhea, and depressed mental function. Because of the variety of ways in which zinc deficiency may present in alcoholic liver disease, clinicians must maintain a high index of suspicion for this nutrient deficiency when caring for these patients. Not only may zinc deficiency occur with alcoholic liver disease, but there also may be altered zinc metabolism. Recent data from alcoholic hepatitis patients demonstrate increased serum levels of the monokine interleukin 1, which is known to cause hypozincemia and an internal redistribution of zinc. This monokine has a host of metabolic functions other than its effect on mineral metabolism that have relevance for alcoholic liver disease such as fever production, neutrophilia, and muscle catabolism. We suggest that the patient with alcoholic liver disease frequently has problems with either zinc deficiency or altered zinc metabolism and the potential implications of this are discussed.

Acrodermatitis↗
PubMed1979

Familial cerebro-macular degeneration (the Stengel-Batten-Mayou-Spielmeyer-Vogt-Stock disease). Evaluation of the photoreceptors.

In a material comprising seven patients with familial cerebro-macular degeneration a grave visual disability had developed within a few years after the onset of the disease, this being at 3 1/2 to 7 years of age. The night vision was only moderately reduced. A severe red-green colour vision defect was demonstrated in three patients. This is in accord with the loss of red and green cone responses found in one patient by chromatic adaptation studies. On the other hand, a remarkably good response of the blue cone system was registered. Normal pulse amplitudes were found by dynamic tonometry in four patients indicating good choroidal circulation. This supports the theory that the degeneration of the neuroepithelium is of primary type. The selectivity in loss of response functions being demonstrated here, might, however, also be related to parallel degenerations taking place in ganglion cells.

Child↗
PubMed1995

Male neonatal death and progressive weakness and immune deficiency in females: an unknown X linked condition.

We report a family with an undiagnosed X linked condition. The grandmother, two of her three daughters, and one of her grand-daughters have a slowly progressive proximal weakness, brisk reflexes, poor bladder function, static reduced night vision, and IgG2 deficiency. The diagnosis of the three living symptomatic females was "hereditary spastic paraplegia plus". They have lost five male children who died in the neonatal period of severe hypotonia and were of low birth weight. Investigations have not led to a unifying diagnosis: myotonic dystrophy, NARP, and X linked hyper IgM were specifically eliminated. Using the hypothesis that the condition is X linked dominant, haplotype analysis of the family suggests that the disease locus is within Xq26-qter. This entity should be considered in the differential diagnosis of families presenting with severe neonatal hypotonia in males and females with symptoms suggestive of complex hereditary spastic paraplegia.

Adolescent↗
PubMed2004

Battlefield Advanced Trauma Life Support (BATLS).

The vast majority of casualties will only require a common sense approach to their preparation for evacuation, by asking simple questions, most problems can be identified and resolved prior to the evacuation. Ask? Are aeromed teams available to undertake this task? (Contact them). If aeromed teams are unavailable but can offer advice, talk to them. Where is the onward destination and are they expecting the casualty. (Check). Is the destination suitable for the casualty and the aircraft type? (Check). What level of training is required to transfer the casualty? (Cbt Med Tech/RGN/MO). Are the appropriate aeromed stretchers and harnesses available? (If not get them). Are all the casualty's documentation and X-rays available for transportation with the casualty? (Check). Does the casualty require a secure airway, intravenous access or fluid resuscitation prior to or during flight? (Ideally, the casualty must be as stable as possible prior to flight). Are all i.v. lines taped and secure. (Check them). Is there sufficient oxygen supply on board for the casualty's(ies) needs to complete the journey and cope with delays? This especially applies if the ventilator is air or oxygen driven. Has the electrical medical equipment required for transportation been cleared for use on the aircraft? (Talk to the aircrew). This equipment may be necessary for in-flight monitoring. Even simple tasks such as counting a pulse rate using the carotid artery, may be impossible in a vibrating airframe. How is the casualty going to be positioned on board the aircraft and does the escort have access? (Find out). If the flight is tactical and at night, the air-crew may be using night vision goggles, can any light be used in the cabin? (On chinooks the crew may be able to provide a blacked out area; in other aircraft torches with green filters will have to be used and monitoring undertaken by touch. Check the situation with the crew and be prepared to adapt). It is very difficult to care for a casualty in the air, particularly on a helicopter. It is extremely important to prepare the casualty properly prior to the flight. A few extra minutes on the ground preparing the casualty may ultimately save their life. However, the tactical situation or the condition of the casualty may dictate the scoop and scoot approach, rather than stay and play.

Adult↗
PubMed1987

Potential nephrotoxic effects of exposure to silver.

A cross sectional study was conducted on workers engaged in manufacturing precious metal powder. Of the 27 workers, 96% had raised urine silver concentrations (range 0.5-52.0 micrograms/l, mean 11.3 micrograms/l) and 92% had raised blood silver concentrations (range 0.05-6.2 micrograms/100 ml, mean 1.0 microgram/100 ml). Nineteen per cent also had raised urine cadmium concentrations (range 1.9-76.0 micrograms/l, mean 11.8 micrograms/l). Most workers had symptoms of respiratory irritation and nose bleeds were reported in eight (30%) of the 27 workers. Deposition of silver in the cornea of the eye was detected in five of eight (63%) of the long term workers. Although not statistically significant, corneal deposition was associated with complaints of decreased night vision. The urinary enzyme N-acetyl-B-D glucosaminidase (NAG) was significantly raised in four individuals and was correlated with blood silver concentrations and age. In addition, the group's average NAG concentration was significantly higher than that found in a control population. No association between age and urinary NAG was found in the control group. Estimated creatinine clearance was also significantly lower in the group exposed to silver than in the control group. Kidney function appears to have been adversely affected by exposures at work but because of the exposure to cadmium the role of silver in causing the decrement in kidney function could not be definitely determined.

Acetylglucosaminidase↗
PubMed2003

Orexin A (hypocretin 1) injected into hypothalamic paraventricular nucleus and spontaneous physical activity in rats.

In humans, nonexercise activity thermogenesis (NEAT) increases with positive energy balance. The mediator of the interaction between positive energy balance and physical activity is unknown. In this study, we address the hypothesis that orexin A acts in the hypothalamic paraventricular nucleus (PVN) to increase nonfeeding-associated physical activity. PVN-cannulated rats were injected with either orexin A or vehicle during the light and dark cycle. Spontaneous physical activity (SPA) was measured using arrays of infrared activity sensors and night vision videotaped recording (VTR). O(2) consumption and CO(2) production were measured by indirect calorimetry. Feeding behavior was assessed by VTR. Regardless of the time point of injection, orexin A (1 nmol) was associated with dramatic increases in SPA for 2 h after injection (orexin A: 6.27 +/- 1.95 x 10(3) beam break count, n = 24; vehicle: 1.85 +/- 1.13 x 10(3), n = 38). This increase in SPA was accompanied by compatible increase in O(2) consumption. Duration of feeding was increased only when orexin A was injected in the early light phase and accounted for only 3.5 +/- 2.5% of the increased physical activity. In a dose-response experiment, increases in SPA were correlated with dose of orexin A linearly up to 2 nmol. PVN injections of orexin receptor antagonist SB-334867 were associated with decreases in SPA and attenuated the effects of PVN-injected orexin A. Thus orexin A can act in PVN to increase nonfeeding-associated physical activity, suggesting that this neuropeptide might be a mediator of NEAT.

Animals↗
PubMed2005

Comparison of the retinal structure and function in four bird species as a function of the time they start singing in the morning.

We postulated that the retinas of bird species that are the earlier singers are more sensitive to low light conditions than species that sing closer to sunrise. The selected species were the American Robin (Turdus migratorius) and the Hermit Thrush (Catharus guttatus) as early singers, the Common Grackle (Quiscalus quiscula) and the Mourning Dove (Zenaida macroura) which join the dawn chorus near sunrise. Scotopic electroretinogram (ERGs) intensity-response functions were obtained from anesthetized birds, following which the animals were euthanized and their retinas processed for histological analysis. Based on k values, generally considered an adequate measurement of the scotopic (rod) retinal sensitivity, all species yielded comparable night vision capabilities. However, based on the maximal (mixed rod-cone response) amplitude of the scotopic b-wave, our results indicate that robins and thrushes yield larger scotopic ERGs compared with doves and grackles, but unexpectedly do not have higher rod:cone ratios. Increased thickness of the retinal inner nuclear layer and higher numbers of ganglion cells in robins and thrushes compared with doves and grackles suggest a greater number of synaptic connections maximizing vision under low light conditions, and might support their higher retinal responses under scotopic conditions. The higher ERG V(max) of robins and thrushes might also be explained, at least in part, by the optics (i.e., their lower minimum F-numbers), resulting in brighter retinal images, rather than from higher sensitivity of their retina. Our results suggest that an early onset of dawn singing might be correlated with the retinal ability to detect the first dim crepuscular lights.

Animals↗
PubMedDate not supplied

Infrared fetoscopy in the sheep.

The strong light sources used in fetoscopy and embryoscopy may cause eye injuries to the fetus. To circumvent this potential hazard, we have successfully used an infrared light source and infrared video camera to perform 'night vision' fetoscopy in a fetal lamb model.

Animals↗
PubMed1994

Phototherapeutic keratectomy in the treatment of Avellino dystrophy.

Avellino corneal dystrophy has rarely been reported in literature. It consists of a combination of granular and lattice dystrophy. Patients may complain of glare and decreased night vision with or without decreased visual acuity, depending on the degree of corneal involvement. Current treatment for this dystrophy includes bandage contact lenses for the erosions or corneal transplant in the case of decreased visual acuity. We describe the first patient with Avellino corneal dystrophy to have been treated with phototherapeutic keratectomy.

Aged↗
PubMed1991

Age-related eye disease, visual impairment, and driving in the elderly.

As people age, a number of visual functions such as acuity, visual field, and night vision deteriorate. This decline in vision is associated in part with an increase in vehicular accidents per mile driven by the elderly. Four age-related ocular conditions--cataract, macular degeneration, open-angle glaucoma, and diabetic retinopathy--are primarily responsible for the decline in visual acuity and visual field in the elderly. Few epidemiologic data are available about these diseases, and at present they cannot be prevented. There is need for more information about visual decline and how it affects driving performance and for development of pragmatic approaches for detecting and assessing the elderly driver with functional visual deficits.

Accidents, Traffic↗
PubMed2004

Quadratic correlation filter design methodology for target detection and surveillance applications.

A novel method is presented for optimization of quadratic correlation filters (QCFs) for shift-invariant target detection in imagery. The QCFs are quadratic classifiers that operate directly on the image data without feature extraction or segmentation. In this sense, the QCFs retain the main advantages of conventional linear correlation filters while offering significant improvements in other respects. For example, multiple correlators work in parallel to optimize jointly the QCF performance metric and produce a single combined output, which leads to considerable simplification of the postprocessing scheme. In addition, QCFs also yield better performance than their linear counterparts for comparable throughput requirements. The primary application considered is target detection in infrared imagery for surveillance applications. In the current approach, the class-separation metric is formulated as a Rayleigh quotient that is maximized by the QCF solution. It is shown that the proposed method results in considerable improvement in performance compared with a previously reported QCF design approach and many other detection techniques. The results of independent tests and evaluations at the U.S. Army's Night Vision Laboratory are also presented.

Journal Article↗
PubMed2006

Spectral response variation of a negative-electron-affinity photocathode in the preparation process.

In order to research the spectral response variation of a negative electron affinity (NEA) photocathode in the preparation process, we have done two experiments on a transmission-type GaAs photocathode. First, an automatic spectral response recording system is described, which is used to take spectral response curves during the activation procedure of the photocathode. By this system, the spectral response curves of a GaAs:Cs-O photocathode measured in situ are presented. Then, after the cathode is sealed with a microchannel plate and a fluorescence screen into the image tube, we measure the spectral response of the tube by another measurement instrument. By way of comparing and analyzing these curves, we can find the typical variation in spectral-responses. The reasons for the variation are discussed. Based on these curves, spectral matching factors of a GaAs cathode for green vegetation and rough concrete are calculated. The visual ranges of night-vision goggles under specific circumstances are estimated. The results show that the spectral response of the NEA photocathode degraded in the sealing process, especially at long wavelengths. The variation has also influenced the whole performance of the intensifier tube.

Journal Article↗