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PubMedDate not supplied

Is the blind spot enlarged in early glaucoma?

PURPOSE: We investigated whether the blind spot is larger in early "preperimetric" glaucoma with already deeply excavated optic discs than in normal persons. METHODS: We examined eight eyes of five patients with definite glaucomatous optic disc cupping but normal visual fields. Ten eyes of five normal healthy volunteers, with normal central excavation, served as controls. With SLO-perimetry we measured the differential light sensitivity 0.5-1.0 degrees outside the disc margins, "within" the center (Goldmann V stimulus) and along the horizontal meridian of the optic discs. Optic disc topography was documented with the Heidelberg Retina Tomograph (HRT). RESULTS: Differential light sensitivities adjacent to the optic discs did not differ in the two groups (normal 8.3dB, early glaucoma 8.4dB). Goldmann IV stimuli presented on the horizontal meridian of optic discs with glaucomatous cupping were seen up to 0.7 degrees centrally (i.e., towards the center) of the disc margin. In the control group this distance was significantly greater (1.3 degrees). The light differential thresholds with stimulus presentation in the disc center (Goldmann V) were significantly higher in the glaucoma group (0+/-2.8dB) than in the normal controls (6.6+/-1.3dB), though disc size was the same in both groups. CONCLUSIONS: Blind spots of normal discs seem to be smaller than those of deeply excavated discs in eyes with early glaucoma, possibly because there is more light scattering by the normal disc surface towards the adjacent functioning retina.

Adaptation, Ocular↗
PubMed2005

Design and testing of low intensity laser biostimulator.

BACKGROUND: The non-invasive nature of laser biostimulation has made lasers an attractive alternative in Medical Acupuncture at the last 25 years. However, there is still an uncertainty as to whether they work or their effect is just placebo. Although a plethora of scientific papers published about the topic showing positive clinical results, there is still a lack of objective scientific proofs about the biostimulation effect of lasers in Medical Acupuncture. The objective of this work was to design and build a low cost portable laser device for stimulation of acupuncture points, considered here as small localized biosources (SLB), without stimulating any sensory nerves via shock or heat and to find out a suitable method for objectively evaluating its stimulating effect. The design is aimed for studying SLB potentials provoked by laser stimulus, in search for objective proofs of the biostimulation effect of lasers used in Medical Acupuncture. METHODS: The proposed biostimulator features two operational modes: program mode and stimulation mode and two output polarization modes: linearly and circularly polarized laser emission. In program mode, different user-defined stimulation protocols can be created and memorized. The laser output can be either continuous or pulse modulated. Each stimulation session consists of a pre-defined number of successive continuous or square pulse modulated sequences of laser emission. The variable parameters of the laser output are: average output power, pulse width, pulse period, and continuous or pulsed sequence duration and repetition period. In stimulation mode the stimulus is automatically applied according to the pre-programmed protocol. The laser source is 30 mW AlGaInP laser diode with an emission wavelength of 685 nm, driven by a highly integrated driver. The optical system designed for beam collimation and polarization change uses single collimating lens with large numerical aperture, linear polarizer and a quarter-wave retardation plate. The proposed method for testing the device efficiency employs a biofeedback from the subject by recording the biopotentials evoked by the laser stimulus at related distant SLB sites. Therefore measuring of SLB biopotentials caused by the stimulus would indicate that a biopotential has been evoked at the irradiated site and has propagated to the measurement sites, rather than being caused by local changes of the electrical skin conductivity. RESULTS: A prototype device was built according to the proposed design using relatively inexpensive and commercially available components. The laser output can be pulse modulated from 0.1 to 1000 Hz with a duty factor from 10 to 90%. The average output power density can be adjusted in the range 24-480 mW/cm2, where the total irradiation is limited to 2 Joule per stimulation session. The device is controlled by an 8-bit RISC Flash microcontroller with internal RAM and EEPROM memory, which allows for a wide range of different stimulation protocols to be implemented and memorized. The integrated laser diode driver with its onboard light power control loop provides safe and consistent laser modulation. The prototype was tested on the right Tri-Heater (TH) acupuncture meridian according to the proposed method. Laser evoked potentials were recorded from most of the easily accessible SLB along the meridian under study. They appear like periodical spikes with a repetition rate from 0.05 to 10 Hz and amplitude range 0.1-1 mV. CONCLUSION: The prototype's specifications were found to be better or comparable to those of other existing devices. It features low component count, small size and low power consumption. Because of the low power levels used the possibility of sensory nerve stimulation via the phenomenon of shock or heat is excluded. Thus senseless optical stimulation is achieved. The optical system presented offers simple and cost effective way for beam collimation and polarization change. The novel method proposed for testing the device efficiency allows for objectively recording of SLB potentials evoked by laser stimulus. Based on the biopotential records obtained with this method, a scientifically based conclusion can be drawn about the effectiveness of the commercially available devices for low-level laser therapy used in Medical Acupuncture. The prototype tests showed that with the biostimulator presented, SLB could be effectively stimulated at low power levels. However more studies are needed to derive a general conclusion about the SLB biostimulation mechanism of lasers and their most effective power and optical settings.

Acupuncture Points↗
PubMed2005

Intercellular communication, NO and the biology of Chinese medicine.

New multiple categories of health disciplines have become popular in the west and integration between the medicinal approaches has become essential. The hypothesis presented here suggests a novel integrative view that combines Western biochemistry with the Chinese medicinal concept of qi. The core for this hypothesis is that transmission of qi along the meridians is based on informational molecules that travel via an intercellular communication system. Acupuncture at specific points enhances the flow of the signaling molecules through this communication system. Nitric oxide is suggested as a prime candidate for such a signaling molecule in the meridian system. The biochemistry of nitric oxide can shed light on the biology underlying Chinese medicine while Chinese medicinal data can provide a clue to the sought after framework for nitric oxide.

Journal Article↗
PubMed2001

Comparison of four enzyme immunoassays with a western blot assay for the determination of type-specific antibodies to herpes simplex virus.

Most current enzyme immunoassays (EIAs) differentiate inadequately between types 1 and 2 herpes simplex virus (HSV) antibodies since significant cross-reactivity exists. We compared 4 IgG type-specific EIAs using a Western blot assay for resolution of discrepant results. The Diamedix had sensitivities of 100% for types 1 and 2 but specificities of only 71% and 61%, respectively. The cross-reactivity rate was 82% in positive samples tested. For HSV types 1 and 2, the Zeus sensitivities were 92% and 98%, respectively; specificities were 72% and 79%, respectively; the cross-reactivity rate was 54%. For HSV types 1 and 2, the Wampole sensitivities were 98% and 95%, respectively; specificities were 68% and 85%, respectively; the cross-reactivity rate was 47%. For HSV types 1 and 2, the Meridian sensitivities were 98% and 90%, respectively; specificities were 96% and 100%, respectively; no cross-reactivity was found between positive samples tested. While the Diamedix, Zeus, and Wampole assays showed good sensitivity, they lacked type specificity. The Meridian EIA offers the highest specificity along with no observed cross-reactivity. This EIA may be an easier, reliable alternative to Western blot for the determination of HSV type-specific antibodies.

Antibodies, Viral↗
PubMed1980

Spatial frequency discrimination thresholds in different orientations.

Spatial frequency discrimination thresholds were obtained for two observers in horizontal, vertical, and oblique (45 degrees, 135 degrees) meridians. Psychometric discrimination functions derived by a forced-choice procedure were essentially the same for the four meridians at lower spatial frequencies. However, at higher frequencies discrimination thresholds were lower for horizontal and vertical stimuli than for oblique stimuli.

Humans↗
PubMed1984

Retinal inhomogeneity. I. Spatiotemporal contrast sensitivity.

Spatiotemporal sine-wave contrast thresholds were measured at four retinal eccentricities: 0 degrees, 3 degrees, 6 degrees, and 12 degrees. Threshold functions of spatial frequency were determined for each eccentricity at two selected temporal frequencies, and functions of temporal frequency at two selected spatial frequencies. Fixation was controlled by stabilizing the retinal image. The stimulus patterns were circular cosine targets confined to annular zones, so that stimulation occurred in all meridians simultaneously. In spite of these unusual conditions, our results were in good agreement with unstabilized, single-meridian data from other laboratories. The spatial-frequency functions obtained at both high and low flicker rates scaled with eccentricity in the same way. For the bandpass functions obtained at 0.5 Hz, the reciprocal of the peak spatial frequency varied linearly with eccentricity. Measured with spatial patterns chosen in accord with this scaling relation, both sets of temporal-frequency functions were essentially independent of eccentricity. Threshold functions at constant velocity were also consistent with the same scaling relation.

Fixation, Ocular↗
PubMed1995

Geometrical theory to predict eccentric photorefraction intensity profiles in the human eye.

In eccentric photorefraction, light returning from the retina of the eye is photographed by a camera focused on the eye's pupil. We use a geometrical model of eccentric photorefraction to generate intensity profiles across the pupil image. The intensity profiles for three different monochromatic aberration functions induced in a single eye are predicted and show good agreement with the measured eccentric photorefraction intensity profiles. A directional reflection from the retina is incorporated into the calculation. Intensity profiles for symmetric and asymmetric aberrations are generated and measured. The latter profile shows a dependency on the source position and the meridian. The magnitude of the effect of thresholding on measured pattern extents is predicted. Monochromatic aberrations in human eyes will cause deviations in the eccentric photorefraction measurements from traditional crescents caused by defocus and may cause misdiagnoses of ametropia or anisometropia. Our results suggest that measuring refraction along the vertical meridian is preferred for screening studies with the eccentric photorefractor.

Computer Simulation↗
PubMed2005

Influence of total reflection on the imaging quality of optical systems.

In the case of total reflection at a boundary surface between two different optical media, the ray reflected at the boundary is spatially shifted with respect to the point where the incident ray intersects the boundary. The light penetrates into the second medium, and the evanescent electromagnetic wave propagates along the boundary. The described effect is called the Goos-Hänchen effect. Our work describes the influence of the Goos-Hänchen effect on the imaging properties of planar optical systems, and a differential equation of a wave-front meridian that corresponds to a reflected bundle of rays is derived. It is shown that the wave front can be described by the d'Alambert differential equation. This equation makes it possible to determine the coordinates of individual points on the wave-front meridian. The influence of total reflection on the value of the Strehl definition of the reflected ray bundle, is also investigated.

Journal Article↗
PubMed2006

Two retinotopic visual areas in human lateral occipital cortex.

We describe two visual field maps, lateral occipital areas 1 (LO1) and 2 (LO2), in the human lateral occipital cortex between the dorsal part of visual area V3 and visual area V5/MT+. Each map contained a topographic representation of the contralateral visual hemifield. The eccentricity representations were shared with V1/V2/V3. The polar angle representation in LO1 extended from the lower vertical meridian (at the boundary with dorsal V3) through the horizontal to the upper vertical meridian (at the boundary with LO2). The polar angle representation in LO2 was the mirror-reversal of that in LO1. LO1 and LO2 overlapped with the posterior part of the object-selective lateral occipital complex and the kinetic occipital region (KO). The retinotopy and functional properties of LO1 and LO2 suggest that they correspond to two new human visual areas, which lack exact homologues in macaque visual cortex. The topography, stimulus selectivity, and anatomical location of LO1 and LO2 indicate that they integrate shape information from multiple visual submodalities in retinotopic coordinates.

Brain Mapping↗
PubMed2004

Retinotopic organization and functional subdivisions of the human lateral geniculate nucleus: a high-resolution functional magnetic resonance imaging study.

Functional magnetic resonance imaging (fMRI) has provided intriguing insights into the topography and functional organization of visual cortical areas in the human brain. However, little is known about the functional anatomy of subcortical nuclei. Here, we used high-resolution fMRI (1.5 x 1.5 x 2 mm3) at 3 tesla to investigate the retinotopic organization of the human lateral geniculate nucleus (LGN). The central 15 degrees of the visual field were mapped using periodic flickering checkerboard stimuli that evoked a traveling wave of activity. The contralateral visual hemifield was represented with the lower field in the medial-superior portion and the upper field in the lateral-inferior portion of each LGN. The horizontal meridian was significantly overrepresented relative to the vertical meridian. The fovea was represented in posterior and superior portions, with increasing eccentricities represented more anteriorly. The magnification of the fovea relative to the periphery was similar to that described for human primary visual cortex. The magnocellular regions of the LGN were distinguished based on their sensitivity to low stimulus contrast and tended to be located in its inferior and medial portions. Our results demonstrate striking similarities in the topographic organization of the macaque and human LGN and support accounts of a constant magnification from the retina through the cortex in both species.

Adult↗
PubMed1977

Two-pulse temporal resolution threshold in the peripheral visual field.

Using a 700-nm light-emitting diode, the minimum inter-pulse interval between two successively flashing pulses presented to 21 retinal loci along horizontal and vertical meridian were measured. The results showed inter-pulse interval changed as a W-shaped function of eccentricity on both meridians.

Fovea Centralis↗
PubMed1993

Comparative evaluation of cryptococcal latex tests.

One hundred and seven specimens (24 CSF and 83 sera) from 90 patients were tested for the presence of Cryptococcus neoformans antigen using the Fairfield Hospital in-house latex agglutination technique and the IMMY and Meridian commercial latex agglutination kits. Forty one specimens (14 CSF and 27 sera) from 27 patients with culture-proven cryptococcosis were positive by both the Fairfield and IMMY latex tests. Thirty nine of these specimens were positive by the Meridian latex test. Two were negative. Sixty six specimens (10 CSF and 56 sera) from 63 patients not known to have cryptococcosis were negative by all 3 tests.

Cryptococcosis↗
PubMed1993

Choroidal blood flow is reduced in chicks with ocular enlargement induced by corneal incisions.

We have previously reported decreased choroidal blood flow (CBF) associated with goggle-induced ocular enlargement and myopia. It was uncertain, however, if this change in CBF was related to the occurrence of ocular enlargement or the increased ocular temperature produced by the goggle. We therefore used corneal surgery-induced ocular enlargement that eliminated the thermal effects observed with goggles to investigate the effects of ocular enlargement on CBF. Central corneal incisions (2 mm in length) were made in the right eye of 4 day old chicks and the wound sutured. In one group, the incision was oriented along the vertical meridian (with the head in its natural position -beak tip 30-45 degrees below horizontal), while in another group the incision was oriented along the horizontal meridian (with the head in its natural position). Age matched controls received no corneal incision. Two weeks later, CBF was measured using laser Doppler velocimetry. After determining CBF, the eyes were removed and axial length, nasotemporal length and dorsoventral length were measured. Ocular enlargement was induced in 11 out of 12 chicks with vertical cuts. The CBF in the operated eye of these 11 animals was 62% of that in the nonoperated eye. Ocular enlargement was also induced in eight of 14 chicks with horizontal cuts. The CBF in the operated eye in these eight chicks was 60% of that in the nonoperated eye. The extent of eye growth was greater in all dimensions in the vertical cut chicks with ocular enlargement than in the horizontal cut chicks with ocular enlargement.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Asymmetry analysis of the retinal nerve fiber layer thickness in normal eyes using optical coherence tomography.

PURPOSE: To investigate the asymmetry of the retinal nerve fiber layer thickness (RNFLT) with respect to the horizontal and vertical meridian and between the right and left eye in normal subjects. METHODS: The RNFLT was measured in 121 normal volunteers by optical coherence tomography (OCT). The RNFLT was analyzed by dividing the circle scanning area (diameter 3.4 mm) around the optic disc into 4 quadrants and 12 sectors. RESULTS: There was a significant difference between the RNFLT of the nasal and temporal quadrant in individual eyes. There was a significant difference between the RNFLT of corresponding sectors with respect to the vertical or horizontal meridian in individual eyes. The nasal and temporal RNFLTs were asymmetrical between the right and left eye in the quadrant and sector analysis. The RNFLT of the nasal and temporal quadrant was thicker in the right eye. The nasal and inferior RNFLT measured by OCT had a significant correlation with degree of refractive error. CONCLUSIONS: In normal subjects without significant anisometropia, there was significant asymmetry of the RNFLT for each eye as well as between the right and left eye.

Adult↗
PubMed1999

A review of current research in microwave resonance therapy: novel opportunities in medical treatment.

Microwave Resonance Therapy (MRT) is a novel medical treatment, which represents a synthesis of the ancient Chinese traditional knowledge in medicine (acupuncture) and recent breakthroughs in biophysics. By affecting the appropriate acupuncture points by the generation of high frequency microwaves (52-78 GHz), remarkable clinical results are being achieved in surgery, orthopedic and traumatology, cardiovascular disorders, urology, gynecology, dermatology, gastroenterology, pulmology, upper respiratory tract, cardiology, neurology, and oncology during the last decade--the MRT being contraindicated only in the cases of acute pain in the abdomen demanding an operation, pregnancy, and menstruation cycle. In this paper the quantum-like macroscopic biophysical basis of the MRT and its technical details are elaborated too, offering a new insight in the mechanisms of the assembling gap junction hemichannels upon the internal microwave (MW) electromagnetic field spatio-temporal maximums at the temporary position of the acupuncture system, and, hence, the very biophysical nature of the temporary psychosomatic health or disease. The quantum-like coherent characteristics of the MRT (sharply-resonant sensory response of the disordered organism, extremely low-intensity and low-energy non-thermal biologically efficient MW radiation, and negligible MW energy losses down acupuncture meridians) might be viewed as a consequence of the existence of biological nonlocal selfconsistent macroscopic quantum potentials, which can give rise to nonlinear coherent EM MW long-range maser-like excitations of biological nonlinear absorption medium with the cells as active centers--with acupuncture meridians related to eigenfrequencies and spatio-temporal eigenwaves distributions of every individual biological quantum system. This suggests that a healthy condition might be considered as an absolute minimum (ground state) of the nonlocal selfconsistent macroscopic quantum potential of the organism. Some disorders of an acupuncture system correspond to higher minimums of the (spatio-temporally changeable) potential hypersurface in energy-configuration space, which possibly explains the higher sensory responses of the more excited (more disordered) acupuncture system and the poor MRT sensory response of the healthy acupuncture system being already in the ground state. Such a picture also supports the EM/ionic "optical" ultralowfrequency modulated MW quantum holographic neural network-like function of the acupuncture system (similar to complex-valued oscillatory holographic Hopfield-like neural networks), and its essential relation to consciousness, as strongly suggested from biophysical modeling of altered states of consciousness. Finally, the ionic aspects of the acupuncture system are considered, too, as well as the relation of ultradian (approximately 2-hour) nasal rhythm recognized in Indian swara yoga and circadian (approximately 24-hour) acupuncture rhythm recognized in Chinese traditional medicine, and their significance for maintaining the ionic balance within acupuncture system, as related to overall health.

Acupuncture Therapy↗
PubMed2006

[Relationship between female ages and the theory of five tones correlated with five zang viscera in Huangdi Neijing].

OBJECTIVE: To find out some evidence that may indicate the theory of voice pitch of the five tones being correlated with the five zang viscera in Huangdi Neijing, which was lost 2 000 years. METHODS: Eight-four healthy females were divided into younger group (<34 years old) and older group (> or =34 years old) according to their ages. The pronunciations of these females were examined by sono-frequency analysis facility. RESULTS: The frequency of Jiao tone was much higher than those of the other tones in both groups (P<0.01) and the frequency of Jiao tone increased as aging. The frequency of Zhi tone in the younger group was higher than that in the older group (P<0.05). CONCLUSION: The results of higher frequency of Jiao tone in females is in accordance with the theory put forward by Ye Gui (a famous doctor in Qing Dynasty of China) that the liver is the congenital base of female life. In traditional Chinese medicine, Jiao tone is correlated with the liver, and Zhi tone is correlated with the heart. The high frequency of Zhi tone in younger females implies that regulating the Small Intestine Meridian of Hand-Taiyang and Heart Meridian of Hand-Shaoyin may be beneficial to the health maintenance of younger female.

Adult↗
PubMed1992

Oculomotor readiness and covert orienting: differences between central and peripheral precues.

The costs produced by invalid precues can depend on the spatial relationship between the cued location and the target location. If oculomotor programs mediate attention shifts, then the effect of varying the spatial relation between the cue and target should be the same for covert orienting (indexed by manual responses) and saccadic responses. We found this to be true only for central precues. With central precues, both manual and saccadic costs were greater when cue and target occurred on opposite sides of the vertical meridian than when they occurred on the same side. With peripheral precues, there were no meridian effects in either response condition, but there was a significant dissociation in the pattern of saccadic and manual costs. For manual responses costs were greater when the target was eccentric relative to the cue, whereas for saccades costs were greater when the cue was eccentric to the target. These results provide additional support for the idea that different orienting mechanisms are engaged by central and peripheral precues. They further suggest that the relationship between oculomotor and attentional orienting may depend on the nature of the precue, with the potential for interdependence being greater with central precues.

Adult↗
PubMedDate not supplied

The relationship between soft tissue anomalies around the orbit and globe and astigmatic refractive errors: a preliminary report.

Corneoscleral limbal masses were created in ten rabbit eyes and upper eyelid colobomas were produced in an additional ten eyes. The resultant changes in corneal curvature were recorded over a one-month period using streak retinoscopy and photokeratometry. By these methods, we have determined that forces at or near the corneoscleral limbus can produce changes in the corneal curvature that lead to refractive errors primarily of the astigmatic variety. There is a shift of the axis of astigmatism towards the meridian 90 degrees away from the external force or an increase of astigmatism along the meridian where the force was exerted. In this study, corneal curvature changed significantly in the coloboma and epibulbar mass groups when compared to the control group. This study supported a causal relationship between soft tissue anomalies and astigmatic refractive errors seen clinically in certain syndromes, such as Goldenhar and mandibulo-facial dysostosis. These findings suggest that patients observed with periorbital soft tissue defects may be at risk for the development of unilateral anisometropic refractive errors and secondary amblyopia. Recognition of this entity is essential in order that adequate therapy can be instituted at an early age.

Animals↗