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PubMed2004

Keratometry measurements in preterm and full term newborn infants.

AIM: To evaluate the relation between postconceptional age and birth weight with keratometric values in preterm and full term infants. METHODS: A prospective cross sectional study was performed. The cohort included 99 infants (198 eyes) admitted to the Neonatal and Neonatal Intensive Care Units at Schneider Children's Medical Center of Israel from February to September 2002. Keratometry in the horizontal and vertical meridians was performed in both eyes of each infant by two ophthalmologists using an autokeratometer. The results were evaluated according to: postconceptual age (<32 weeks, 32-36 weeks, >36 weeks) and birth weight (<1500 g, 1501-2500 g, >2501 g). RESULTS: Corneal curvature measurements decreased progressively with both postconceptual age and birth weight. At <32 weeks, mean (standard deviation) readings were 63.3 (3.2) diopters (D) for the horizontal meridian and 57.3 (2.6) D for the vertical meridian; corresponding values at >36 weeks were 54.0 (3.0) D and 50.7 (2.4) D. In the <1500 g group, mean (SD) readings were 61.3 (3.9) D for the horizontal meridian and 56.0 (2.9) D for the vertical meridian; corresponding values in the >2501 g group were 51.3 (2.1) D and 48.6 (1.8) D. CONCLUSIONS: There is an inverse relation of horizontal and vertical keratometric values with both postconceptional age and birth weight. Highest readings were noted in the babies with the lowest birth weight and youngest postconceptional age. The decrease in corneal dioptric power to normal values is linear and is apparently part of the normal ocular maturation.

Birth Weight↗
PubMed1981

Topography of the cortico-cortical connections from the striate cortex in the cat.

Injections of radioactive amino acids were placed in regions of the striate cortex of cat representing central, intermediate and peripheral parts of the horizontal meridian and also in regions of lower and upper visual field representations near the vertical meridian. The study of cortico-cortical connections arising from these points revealed several retinotopic arrangements in the distribution of these connections and, it is argued, of the extrastriate cortical recipient areas themselves. On retinotopic distribution exists along the banks of the middle suprasylvian sulcus, in which lower and upper visual fields are rostral and caudal, respectively, and central and peripheral visual fields are ventral (or lateral) and dorsal (or medial), respectively, in the banks. This arrangement is called the lateral suprasylvian area (LS). Another retinotopic distribution exists along the caudal bank of the posterior suprasylvian sulcus. In this region, called the posteroior suprasylvania area(PS), points at, or near, the horizontal meridian are mainly represented, central and peripheral parts of which are located dorsaly and ventrally in the sulcus, respectively. Two other retinotopic distributions of connected exist in visual areas 2(V2) and 3 (V3) of Hubel and Wiesel, in which lower and upper visual fields are situated rostrally and caudally in these areas, respectively. Along the horizontal meridian, central is lateral in V3 and medial in V2, while more peripheral points, (15 degrees, 45 degrees) of V3 and V2 approach each other, in a mirror image fashion, along the coronal plane. However, representations of these peripheral parts of the horizontal meridian are repeated twice again: extensively, caudally along the lateral border of area 18, and more restrictively rostrally, along the lateral border of area 18.

Animals↗
PubMed1983

Meridional variations of the scotopic sensitivity in the human retina.

The absolute threshold of the dark-adapted retina for a 1 degree circular white light stimulus located at 15 degrees eccentric to the fovea was measured on four meridians. In each of the 11 tested subjects the sensitivity was found to be higher on the 90 degrees suprafoveal vertical meridian, on average by 0.3 log nLa compared to the subfoveal vertical meridian. On the two oblique 45 degrees and 135 degrees meridians of the upper retina the sensitivity was only very slightly lower compared to the 90 degrees meridian.

Adolescent↗
PubMed2004

A principal component analysis of multifocal pattern reversal VEP.

Multifocal visual evoked potentials (mfVEP) were recorded with three channels from 31 control subjects. A principal component analysis was applied to all local responses. The first principal component reversed polarity above and below the horizontal meridian in the case of the midline channel and across the vertical meridian in the case of the lateral channel. In addition, the first principal components of the responses around the vertical meridian were reversed in polarity compared to those around the horizontal meridian, consistent with the region near the vertical meridian lying outside the calcarine fissure. A model was proposed that allowed for the construction of a coronal section of V1 based on the distribution of the first principal component. This approach provides a means of deriving a V1 component from mfVEP recordings with only three recording channels.

Adult↗
PubMed1979

Effect of meridional disparity on depth perception.

When a meridional-size lens is used to provide magnification in the horizonal meridan for one eye the resulting stereopsis distortion is readily accounted for in the terms of the binocular disparity caused by changed angular relations. When the same size lens is used to magnify the vertical meridian for one eye there is an opposite stereoscopic distortion for which is no ready geometric explanation. A perceptually induced mechanism operating in the vertical meridian has been suggested by Ogle. In the present experiment, apparatus was designed to introduce disparity of binocularly fused targets successively in each of several oblique meridians independent of the stereopsis measuring targets. Unlike the above-mentioned results obtained with size lenses, the induced stereoscopic distortion was in the same direction and of essentially the same magnitude for disparity in every meridian. It would follow that the perceptually induced mechanism is not exclusive to the vertical meridian.

Depth Perception↗
PubMed1991

Effects of acupuncture on the plasma atrial natriuretic peptide. Aldosterone and renin activity in man.

To investigate the effect of acupuncture on the plasma levels of hormones, we have applied acupuncture in the meridian points. Two meridian points, B25 and B15, were selected for the hand-running acupuncture application. The plasma levels of immunoreactive atrial natriuretic peptide, aldosterone, and renin activity were measured by radioimmunoassay. Acupuncture in the meridian point B23 decreased plasma levels of immunoreactive atrial natriuretic peptide, while that in the B15 increased plasma levels of immunoreactive atrial natriuretic peptide. Acupuncture in the B15 decreased plasma levels of aldosterone while that in the B23 decreased plasma renin activity. These results suggest that acupuncture in the specific meridian points may have sites specific regulatory function for the hormone levels and that the meridian points, B23 and B15, may have control mechanism for the regulation in the body fluid and electrolytes balance.

Acupuncture Points↗
PubMed2006

[Analysis of curvature distribution on corneal surface].

PURPOSE: To detect the characters of the curvature distribution from a mathematical point of view. METHODS: Subjects were measured with Orbscan II corneal topography system. Anterior and posterior corneal radius of curvature and thickness of the points located 1.5 mm, 2.5 mm, 3.5 mm and 4.5 mm away from the corneal apex on certain meridians, including 0 degrees, 30 degrees, 60 degrees, 90 degrees, 120 degrees, 150 degrees, 180 degrees, 210 degrees, 240 degrees, 270 degrees, 300 degrees and 330 degrees meridians, were collected. Distributions of corneal curvature between the two principal meridians were discussed. RESULTS: The curvature of oblique meridian might be described with the formula F' = Fa+(Fb-Fa) xSin2alpha. CONCLUSIONS: Anterior and posterior corneal surfaces are similar to toric surface. The distributions of corneal curvature between the two principal meridians have something to do with the law of sine.

Adult↗
PubMedDate not supplied

Comparison of keratometric readings as obtained by Javal Ophthalmometer and Corneal Analysis System (EyeSys).

We examined 92 normal eyes using Javal Ophthalmometer and Corneal Analysis System (EyeSys) intending to compare the keratometric readings obtained by these two instruments. Dioptric power and location at flatter and steeper meridians, keratometric astigmatism values, and average central keratometric power were measured in the central cornea of all eyes. Statistical analysis showed significant differences in flatter meridians' mean power values (mean difference = 0.13 D, P = .008), mean keratometric astigmatism values (mean difference = -0.20 D, P = .001) and steeper meridians' location (mean difference = 7 degrees, P = .0001). There was no significant difference in steeper meridians' mean power values (mean difference = -0.06 D, P = .38), flatter meridian location (mean difference = 5.9 degrees, P = .07), and mean average central keratometric power (mean difference = 0.03 D, P = .471). Clinically meaningful difference was observed only in keratometric astigmatism readings of eyes with keratometric astigmatism higher than 1.50 D (mean difference = -0.84 D). For all the other parameters measured, the differences between the two instruments readings were clinically acceptable.

Adolescent↗
PubMed1988

Visuotopic organization and extent of V3 and V4 of the macaque.

The representation of the visual field in areas V3 and V4 of the macaque was mapped with multiunit electrodes. Twelve Macaca fascicularis were studied in repeated recording sessions while immobilized and anesthetized. V3 is a narrow strip (4-5 mm wide) of myeloarchitectonically distinct cortex located immediately anterior to V2. It contains a systematic representation of the central 35-40 degrees of the contralateral visual field; the representation of the upper quadrant is located ventrally in the hemisphere and that of the lower quadrant, dorsally. There is a small gap between the dorsal (V3d) and ventral (V3v) portions of V3. The representation of the horizontal meridian is adjacent to that in V2 and forms the posterior border of both V3d and V3v. Most or all of the anterior border of V3d consists of the representation of the lower vertical meridian. The entire anterior border of V3v consists of the representation of the upper vertical meridian. V4 is a strip of myeloarchitectonically distinct cortex 5-8 mm wide, immediately anterior to V3. It contains a coarse, but systematic, representation of approximately the central 35-40 degrees of the contralateral visual field. The representation of the upper visual field is located ventrally in the hemisphere. Most of the representation of the lower visual field is located dorsally. The posterior border of V4 corresponds to the representation of the vertical meridian, and the representation of the horizontal meridian is located at or near its anterior border. In both V3 and V4, the representation of the central visual field is magnified relative to that of the periphery. In both areas, the size of receptive fields increases with increasing eccentricity; however, at a given eccentricity, the receptive fields of V4 are larger than those of V3.

Animals↗
PubMed1979

A mutant of Tetrahymena thermophila with a partial mirror-image duplication of cell surface pattern. I. Analysis of the phenotype.

Cells of a mutant clone, CU-127, of Tetrahymena thermophila (formerly T. pyriformis, syngen 1) manifest three anatomical abnormalities. First, the stable number of ciliary meridians is 21-25, above the usual number (17-21) in this species. Second, up to 30% of the cells have two oral apparatuses (OAs), one normal and the other abnormal. Third, more than one-half of the cells possess two distinct sets of contractile vacuole pores (CVPs). In some living cells two contractile vacuoles are seen. These abnormalities have persisted unchanged during more than 500 generations of vegetative propagation, and are similarly expressed in subclones. The normal and abnormal OAs are topographically segregated, with normal OAs developing along the "primary oral axis" and abnormal OAs developing along a "secondary oral axis" that is situated 170 degrees of the cell circumference to the cell's right of the primary oral axis. CVPs always appear within this 170 degree arc and never within the complementary 190 degrees arc to the left of the primary oral axis. A unique feature of the CU-127 clone is the commonly expressed mirror image reversal of the structural pattern of OAs that develop along the secondary oral axis. The primordia of such OAs initially appear (as usual) to the cell's left of a ciliary meridian, but as membranelles develop the frequently come to be oriented in a mirror image of the normal pattern, and an undulating membrane sometimes develops on the wrong (left) side of the oral primordium. When two sets of CVPs are formed, their average positions are roughly equidistant with respect to the two oral axes, with the two sets located 50-60 degrees to the right and left respectively of the primary and secondary oral axis. Such cells are thus bilaterally symmetrical about a plane defined by the central longitudinal axis and the halfway point between the two CVP sets (see Fig. 25). This plane bisects the cell into a normal and a "reversed" half-cell. However, only oral asymmetry and large-scale CVP positioning are subject to such reversal; all ciliary meridians remain of normal asymmetry and all CVPs are situated on the left side of CVP meridians. The fact that major aspects of large-scale cellular organization can be reversed while the "fine-positioning" associated with the ciliary meridians remains normal indicates that the two aspects of cell organization are distinct.

Animals↗
PubMed1997

Intense peripheral electrical stimulation evokes brief and persistent inhibition of the nociceptive tail withdrawal reflex in the rat.

In a study of modulation of nociception by sensory inputs, electrical stimulation was applied to specific sites in the hindlimb and effects on the nociceptive tail withdrawal reflex were monitored in the lightly anaesthetized rat. Stimulation was applied to previously defined sites in the hindlimb, meridian points femur-futu (ST-32), fengshi (GB-31) and zusanli (ST-36). It consisted of a 4 Hz train of 2 ms square pulses given for 20 min at 20 x the threshold intensity required for muscle twitch. Tail withdrawal was provoked by application of a noxious heat stimulus applied to the tip of the tail. Results were expressed as a percentage of the maximal possible inhibition which is achieved when the post-treatment latency is 2 x the pre-treatment latency otherwise known as the cut off. During stimulation, the latency of the withdrawal increased to approximately 70% of the maximal possible inhibition. Following stimulation, the inhibition persisted for > 1 h. Stimulation at 2 or 6 Hz elicited similar effects but stimulation at 8 Hz evoked inhibition during the stimulation only. Stimulation applied to sites away from defined meridian points inhibited tail withdrawal during the stimulation; no post-stimulation effect was produced. In acutely transected animals (< or = 48 h), stimulation of meridian points elicited a small, brief increase in latency but during stimulation only. At 7 and 14 days after spinal transection, this response during stimulation was greater in magnitude and a brief post-stimulation increase was also observed. The return of this latter effect was coincident with the return of bladder function. These data suggest that high intensity, low frequency electrical stimulation of hindlimb meridian points in the lightly anaesthetized rat produces both brief and persistent inhibitory effects on the nociceptive tail withdrawal reflex. These effects appear to be elicited by different mechanisms. The persistent effect may represent a plastic change in central inhibitory mechanisms. Data from spinal animals indicate a major participation of supraspinal structures but that spinal mechanisms are also capable of sustaining both types of effect.

Animals↗
PubMed2005

Is there any energy transfer during acupuncture?

Acupuncture therapy is based on the principle of restoring equilibrium of the body's energy state by regulating the flow of Qi in the corresponding meridians and acupoints. The purpose of this study was to determine whether bio-energy transfer occurs during acupuncture of the meridians. We treated 20 normal healthy subjects with acupuncture and measured changes in the direct current (DC) potential between the stomach meridian points ST-39 and ST-37 in response to invasive insertion of a needle at ST-36. Using a crossover study design, the practitioner performed the procedure on each subject once with bare (uncovered) hands (ABH) and once wearing surgical gloves (ASH) to shield the electric energy transfer. ABH produced a response pattern to each stimulation, whereas ASH produced a response pattern only to the first step. ABH elicited a significantly higher response potential than did ASH (p < 0.001). These results suggest that there may be bio-energy (Qi) transfer during acupuncture along the meridians. This transferred bio-energy (Qi) seems to act as an electromotive force, which is purported to remove the stagnation or blockage of energy and restore an equilibrium state.

Acupuncture Therapy↗
PubMed1992

Anatomy and classification of acupoints.

Acupuncture points are conceived as points on the skin reflecting visceral conditions and the sites for acupuncture treatment. In the skin, acupoints tend to show higher electric conductivity and have higher concentration of neural and vascular elements as well as mast cells. Locations of some acupoints correspond to the motor points, others to the Golgi tendon organs. There is a group of midline acupoints. Most acupoints are associated with meridians and are known as meridian points. The nature of meridians is under scientific scrutiny. For identification of canine acupoints, the human meridian nomenclature was adopted.

Acupuncture Points↗
PubMed2005

[Experimental study on conduction of Gong tonality vibromusic sound wave in the healthy human body].

OBJECTIVE: To study the conduction of Gong tonality vibromusic sound wave along meridians in healthy human body, and investigate differences of the sensitivity of different meridians and genders to this vibromusic message. METHODS: Emit the Gong tonality music signal under the water and then investigate the responses of different acupoints and control points at the tissue of the same level to the vibromusic sound wave. RESULTS: There were differences of sensitivity to music waves at source acupoints on the foot, sensitivity of Zusanli (ST 36) was significantly higher than its control point (P < 0.05), and there was difference between genders in the sensitivity of Sanyinjiao (SP 6) and Yinlingquan (SP 9) to music sound wave. CONCLUSION: Gong tonality vibromusic sound wave can conduct along meridians in healthy human body, and there are differences between different meridians and different genders in the sensitivity to the music sound wave.

Acupuncture Points↗
PubMed1999

The utility of entoptic perimetry as a screening test for cytomegalovirus retinitis.

OBJECTIVE: To determine the sensitivity and specificity of entoptic perimetry as a noninvasive test for detecting retinal damage due to peripheral cytomegalovirus (CMV) retinitis. DESIGN: A masked study comparing entoptic perimetry with fundus photography under 4 experimental conditions (determined by increasing pixel sizes) on 2 separate testing sessions. SETTING: Acquired immunodeficiency syndrome Ocular Research Unit at the University of California, San Diego. PATIENTS: Twenty-four human immunodeficiency virus-positive and 8 human immunodeficiency virus-negative subjects; 21 eyes with documented CMV retinitis, and 26 eyes that were retinitis free. MEASUREMENTS: For each testing session, screening method, and condition, the presence of CMV retinitis was determined for each meridian (i.e., clock hour), each quadrant (consisting of 3 meridians), and each eye (consisting of all meridians); the amount of retinitis was defined as the percentage of meridians or quadrants with CMV retinitis. RESULTS: Entoptic perimetry was as sensitive and specific as fundus photography in determining the presence of CMV retinitis. Determination of the amount of CMV retinitis tended to be underestimated by perimetry for larger pixel sizes. CONCLUSION: Entoptic perimetry may be an effective and inexpensive alternative to fundus photography for CMV retinitis in hospitals and community clinics.

AIDS-Related Opportunistic Infections↗
PubMed1996

Measurement of Goldmann visual fields in older children who received cryotherapy as infants for threshold retinopathy of prematurity.

BACKGROUND: Cryotherapy administered to eyes with severe acute-phase (threshold) retinopathy of prematurity benefits retinal structure and visual acuity compared with the natural course of the retinopathy. OBJECTIVES: To determine the extent of peripheral field abnormalities in eyes with threshold retinopathy of prematurity that had retinal structure preserved by cryotherapy. METHODS: Kinetic perimetry was performed with a Goldmann perimeter by masked testers on patients in whom bilateral threshold retinopathy of prematurity developed and who had been randomly assigned to undergo cryotherapy in one eye and no cryotherapy in the fellow eye. With the V-4-e and the II-4-e targets, eight meridians were tested: 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees. The median value of three presentations in each meridian was accepted as the extent in that meridian. RESULTS: Fourteen eyes (eight treated and six control) of eight patients (mean age, 9.9 years; range, 6 to 11 years) had adequate vision to undergo fields testing. Mean (+/-SE) extent of visual field for treated vs control eyes was 36 degrees +/- 3 degrees vs 46 degrees +/- 6 degrees for the II-4-e target and 49 degrees +/- 4 degrees vs 59 degrees +/- 6 degrees for the V-4-e target. This difference was consistent across all eight meridians for either target, and repeated-measures analysis of variance showed that cryotherapy was associated with smaller visual field extent for both target sizes (P=.08). CONCLUSION: The results of this small pilot study suggest that eyes that have retinal structure and acuity preserved by cryotherapy for severe acute-phase retinopathy of prematurity have slightly smaller visual fields than untreated eyes with severe acute-phase retinopathy of prematurity that had vision preserved.

Acute Disease↗
PubMed1975

The representation of the visual field in the lateral geniculate nucleus of Macaca mulatta.

Microelectrode recording techniques were used to investigate the projection of the visual field into the lateral geniculate nucleus (LGN) of Macaca mulatta. The data were used to construct charts plotting visual direction, designated in terms of azimuth and elevation, onto sections of the nucleus cut in coronal, sagittal and horizontal Horsley-Clarke planes. The projection of the horizontal meridian divides the LGN along its plane of symmetry into a medial-superior half having negative elevations and a lateral-inferior half having positive elevations. Elevations become more positive or negative with distance from this plane. Azimuths closest to the vertical meridian are located posteriorly, while the most peripheral azimuths are found at the anterior pole. Two families of surfaces representing visual directions of constant azimuth and elevation are described. Visual field zones of increasing eccentricity are represented serially along the posterior-anterior axis of the LGN, with the foveal area restricted to the posterior pole and the monocular crescent projecting to the anterior pole. The mapping is completely continuous across the horizontal meridian. The edges of the stacked cell laminae exposed around the periphery of the LGN form an oval band which receives the projection of the perimeter of the contralateral hemifield. The vertical meridian is represented by the posterior two-thirds of this band, while the periphery of the hemifield projects to the anterior third. The central visual field out to the optic disc is represented by six cell layers, while the rest of the binocular field projects to four layers only (2 parvocellular and 2 magnocellular). The monocular crescent is represented by one parvocellular and one magnocellular layer. Features associated with the projection column of the optic disc are integrated into the transition from six to four layers. Details of the receptive field topography in the vicinity of the optic disc discontinuities indicate that these gaps are produced by intralaminar mechanisms. The magnification factor (mm-3/steradian) increased monotonically from peripheral visual fields to the foveal center, varying over a range of three decades. This range is intermediate between those derived from data reported in the literature for the retina and the striate cortex. The ratio of LGN magnifications at any two angular eccentricities is a power function, with an exponent of 1.34, of the corresponding ratio of retinal ganglion cell densities. Similarly, the ratio of cortical magnifications (mm-2/steradian) at any two eccentricites is a power function, with an exponent of 1.35, of the corresponding ratio of LGN magnifications.

Animals↗
PubMed1979

A neurophysiological determination of the vertical horopter in the cat and owl.

We have undertaken a determination of the vertical horopter in two species by simultaneously mapping the receptive field positions of binocular cortical neurons at various elevations along the zero azimuthal meridians. In the paralyzed cat our recordings show that the zero meridians of the two eyes are parallel and vertical under paralysis. Slit-pupil photographs demonstrate that paralysis induces an average net intorsin of 9 degrees between the two eyes. Correction back to the unparalyzed state results in the zero meridians themselves being out-torted with respect to each other. Since the two eyes' zero meridians define physiologically the positions of corresponding retinal points, this out-torsion results in a vertical horopter in the mid-sagittal plane which is tilted away from the alert, unparalyzed cat. The limited eye movements of the owl permit the use of an unparalyzed preparation; it is therefore possible to avoid the problem of the cyclotorsion under paralysis which occurs in the cat. The results of our physiological analysis in the burrowing owl (Speotyto cunicularia) also reveal a tilted horopter in this terrestrial avian species.

Animals↗