Influence of acquisition parameters on hemodynamic measurements with the Heidelberg Retina Flowmeter at the optic disc

Asymmetrical IgG molecules are characterised by the presence of a mannose-rich oligosaccharide group in only one of the two Fab fragments, which impairs the corresponding paratope, causing such molecules to behave as univalent antibodies and therefore as antigen blockers [1-3]. During human and murine pregnancy, an increase has been detected in asymmetrical IgG molecules in serum and those bound to the placenta, which normally releases factors capable of modulating the immune response. It thus seemed of interest to investigate the effect of placental culture supernatants (PCS) on in vivo and in vitro synthesis of rat immunoglobulin IgG1, IgG2a, IgG2b and IgG2C, particularly the ratio of symmetrical and asymmetrical molecules in each isotype. The effect of PCS was determined in vivo by means of passive transfer to virgin females and in vitro by analysing the supernatants of spleen cells cultured in the presence of PCS. The results showed that neither pregnancy status nor PCS were capable of modifying serum levels of IgG2a, IgG2b or IgG2c, whereas the level of IgG1 was reduced. When PCS were added to the spleen cells cultures, an in vitro increase was observed in IgG2a, IgG2b and IgG2c production. The separation of symmetrical from asymmetrical IgG molecules was performed by affinity chromatography in Concanavalin A-Sepharose, as such lectin binds high mannose sugars present only in asymmetrical IgG molecules. It is shown that pregnancy and PCS induce an increase in IgG1 and IgG2 molecules asymmetrically glycosylated, capable of binding to ConA-Sepharose. Therefore, the placenta is capable of releasing factors which can regulate the relative proportion of asymmetrical IgG molecules and induce quantitative and qualitative modifications of the in vitro and in vivo produced antibodies.     

Effect of the contour line on cup surface using the Heidelberg Retina Tomograph

BACKGROUND: Significance of topometric follow-up examinations of the optic nerve head in glaucomatous eyes depends on the reproducibility of the calculated parameters. Since the definition of the standard reference plane in software version 1.11 of the Heidelberg Retina Tomograph has been changed, intrapapillary parameters depend directly on the position of the contourline in the sector between -10 degrees to -4 degrees, and therefore on the observer variability to determine the disc border. We evaluated intra- and interobserver variability and present a simple approach to increase reproducibility. METHOD: The disc border of 4 glaucomatous eyes, 3 ocular hypertensive eyes and 3 eyes of healthy subjects were traced by two observers, 5 times using the free draw mode and 5 times by the addition of contourline circles. RESULTS: We found a median variability of the mean disc radius in sector -10 degrees to -4 degrees of 51 microns, which defines the position of the standard reference plane, resulting in a median variability of the position of the standard reference plane of 33 microns which caused a variability of 81 microns2 of the cup area. Addition of contourline circles smoothing the final contourline along the border of the optic disc resulted in a decrease of the coefficient of variation of the standard reference plane of 3.76% (6.76% vs. 3.0%), of the cup area of 2.34% (3.87% vs. 1.53%) and of the rim volume of 3.41% (9.75% vs. 6.34%). CONCLUSION: The calculation of the cup area using software version 1.11 of the Heidelberg Retina Tomograph depends on observer variability. The addition of contourline circles to define the final contourline along the disc border increases reproducibility. However, in follow-up of topometric examinations of the optic nerve head the software supported transfer mode should be used. Comparing topometric data of an individual optic disc in follow-up suppose the same definition of the contourline. Therefore, topometric data evaluated using software version 1.10 or earlier needs to be recalculated.     

Volumetric analysis of early macular edema with the Heidelberg Retina Tomograph in diabetic retinopathy

OBJECTIVE: This study describes a new method for the quantification of diabetic macular edema by volumetric analysis with the Heidelberg Retina Tomograph (HRT) scanning laser ophthalmoscope. DESIGN: Topographic images of the macula were obtained in 25 consecutive patients who fitted the inclusion criteria. Twenty age-matched control subjects were randomly selected for a similar examination. PARTICIPANTS: Twenty normal control eyes and 32 eyes of 25 patients with diabetes mellitus were studied. INTERVENTION: Patients with diabetes were examined by HRT and slit-lamp biomicroscopy with a contact lens. On HRT, the volumes above reference plane bound by three consecutive circles centered at the fovea (diameter, 1, 2, and 3 mm) were measured. Measurements were repeated three times in a masked fashion, and the mean measurements were used for the analysis. MAIN OUTCOME MEASURES: Visual acuity, macular edema, and volume above reference plane were measured. RESULTS: There were 19 diabetic eyes with clinical macular edema (deemed positives) and 13 without edema (deemed negatives). Diabetic eyes with macular edema had statistically greater volumes above reference plane than did diabetic eyes without edema (P < 0.001) and greater than the control eyes (P < 0.001) for all three circles. There was no statistically significant difference between volumes measured in eyes without macular edema and control eyes (P = 0.42 for the 1-mm diameter circle; P = 0.72 for the 2-mm diameter circle; and P = 0.19 for the 3-mm diameter circle). For the two smallest circles only, the sensitivity of the HRT was 78.94%, and the specificity was 84.61%. None of the patients missed on the two smallest circles would have been positively identified on the 3-mm diameter circle. CONCLUSION: The HRT can detect and quantify macular edema in diabetes by volumetric analysis with the method the authors have described. It is sufficient to measure the volumes above reference plane of two circles centered on the fovea and measuring 1 and 2 mm in diameter because the 3-mm diameter circle does not increase the system's sensitivity.     

Prospective study design for the Heidelberg Retina Tomograph: the effect of change in focus setting

Infections are a major cause of mortality among immunosuppressed cancer patients. The oral cavity is a possible reservoir for those microorganisms, both commensal and acquired, whose virulence is exacerbated in the immunosuppressed patient. The mouth consists of multiple habitats offering ecological niches to a variety of organisms. The object of this article is to review the literature devoted to quantitative and qualitative variations in the flora of the oral cavity during immunosuppressive treatment of cancer patients. Examination of these different studies reveals modifications of the commensal flora, as well as an increase in Gram negative rods, in staphylococci and in yeasts. These data confirm the necessity for constant surveillance of the oral cavity during chemotherapy.     

Ophthalmoscopic measurement of the optic disc

PURPOSE: The authors evaluated whether the optic disc dimensions can be measured directly by ophthalmoscopy without the use of a fundus camera or special ophthalmoscope. MATERIALS AND METHODS: The horizontal and vertical disc diameters were measured ophthalmoscopically in 158 eyes of 95 subjects using a standard Goldmann three-mirror contact lens and a commercial slit lamp with adjustable length of the beam. The refractive error ranged from -7.25 to 3.5 diopters. Based on these direct measurements, the authors calculated the disc area by applying a modified formula for an ellipse, where area = pi/4 x the horizontal diameter x the vertical diameter. Additionally, the authors determined by planimetry the diameters and area of the disc on color photographs after correcting the ocular and photographic magnification. RESULTS: The values of the disc diameters as determined by photography were x1.27 larger than those measured with the Goldmann contact lens. Taking into account this constant correction factor of 1.27 for all eyes examined, the disc diameters, as measured by the Goldmann lens, varied by 0.11 +/- 0.06 mm or 5.8% +/- 3.5% from the values measured on the photographs. This error decreased slightly (P = 0.04) with increasing disc size. It was independent of the refractive error. The calculated disc area based on the ophthalmoscopically determined disc diameters differed by 9.4% +/- 6.6% from the disc area as measured by planimetry on the photographs. CONCLUSIONS: For clinical purposes, the optic disc and other structures of the posterior fundus can be measured by ophthalmoscopy using a Goldmann contact lens and a slit lamp with adjustable beam length. The optic disc area can be calculated by the formula: horizontal disc diameter x vertical disc diameter x pi/4.     

Relation between size of optic disc and thickness of retinal nerve fibre layer in normal subjects

The genus Clinostomum is a cause of parasitic laryngo-pharyngitis. We report the 15th case of Clinostomum sp. infection in Japan. A 29-year-old female visited our hospital because of throat discomfort and expectoration of a worm by sneezing on November 17, 1997. The pharyngitis was caused by the worm. The worm was morphologically identified as the adult of the genus Clinostomum.     

Unilateral retinitis pigmentosa and pit of optic disc

A 59-year-old woman had an unusual association of unilateral retinitis pigmentosa and optic pit with macular pathologic features in the same eye. A general ophthalmic and electrophysiologic investigation characterized the patient's condition functionally, without defining the basic defect responsible for this peculiar association. While an exact explanation of this occurrence cannot be given at this time, the possibility of coincidence or abiotrophy with developmental defects can be suggested as its intimate mechanism.     

Detection of optic disc changes with Glaucoma-Scope probability maps

Before use of cardiovascular surgical techniques and procedures in humans, many experiments, e.g., hypothermic circulatory arrest and cardiopulmonary bypass using the heart-lung machine, have been performed in the dog. As a consequence experimental canine cardiovascular surgery is highly developed. This has not resulted in the routine performance of open heart surgery in veterinary medicine, probably because of the high costs. Cardiovascular surgery in the dog is generally limited to interventions not depending on hypothermic circulatory arrest or cardiopulmonary bypass. The clinical cardiovascular surgery in dogs can be divided into routine and more specialized interventions. The first category includes correction of peritoneopericardial diaphragmatic hernia, pericardial fenestration in dogs with pericardial effusion, treatment of persistent right aortic arch, and patent ductus closure. The specialized interventions include dilation of pulmonic and aortic stenoses and pacemaker implantation. The diagnosis and surgical treatment of such diseases is described. New developments in cardiovascular surgical treatment that can be expected include catheter techniques for occlusion of shunts and dilations using balloons, because the financial costs of these procedures are not prohibitive.     

Ophthalmoscopic assessment of the size of the optic nerve papilla

PURPOSE: To examine whether the optic disc size can be measured with common ophthalmoscopic lenses. PATIENTS AND METHODS: The horizontal and vertical disc diameters in 125 eyes of 65 patients were measured ophthalmoscopically using a commercial slit lamp with adjustable length of the beam and a Volk 60 diopters lens or a Volk Superfield lens. The refractive error of the subjects ranged between -7.25 D and +3.25 D (mean +/- S.D.: -0.34 +/- 1.77). Based on these measurements we calculated the optic disc area by applying a modified formula for an ellipse, where area = horizontal diameter x vertical diameter x pi/4. Additionally, we measured planimetrically the horizontal and vertical diameters of the optic disc on color stereo disc photographs after correcting the ocular and camera magnification according to Littmann's method. RESULTS: The values of the horizontal and vertical disc diameters evaluated on the photographs were by factors of 1.0 and 1.5 larger than those values measured with the Volk 60 D lens, and the Volk Superfield lens, respectively. Taking into account these constant linear correction factors, the optic disc diameters as measured by the Volk 60 D lens and the Volk Superfield lens varied by 0.11 +/- 0.09 mm (5.9 +/- 5.1%), and 0.11 +/- 0.09 mm (5.9 +/- 4.9%), respectively, from the values measured on the photographs. The error for the ophthalmoscopic measurement of the disc diameters decreased slightly with increasing disc size. With highly myopic eyes excluded, it was independent of the refractive error. CONCLUSION: For clinical purposes, the optic disc and other structures of the posterior fundus can be determined by ophthalmoscopy using a slit lamp and commonly used ophthalmoscopical lenses.     

Asymmetry of retinitis pigmentosa-related to initial optic disc vasculitis

A case of highly asymmetric retinitis pigmentosa is reported. Signs of pigmentary retinopathy appeared in the first eye following optic disc vasculitis or neuroretinitis of unknown etiology. Within 2 years the visual field became markedly restricted and the dark adaptation thresholds elevated. Twelve years later this eye was almost blind and the ERG was non-recordable. In the fellow eye, the first pigmentary changes were observed 5 years after the initial presentation, and the progression was slow. Nineteen years after the initial examination the visual field of the less affected eye was constricted to 30 degrees nasally and 60 degrees temporally, the dark adaptation threshold was only slightly elevated, and the full-field ERG was within normal range. It is possible that neuroretinitis or vasculitis of the optic disc caused the earlier onset and the more progressive course of pigmentary retinopathy in the initially affected eye.     

Photography of the optic disc in the management of glaucoma (author's transl)

Repeated photography of the optic disc is helpful in the management of 1. patients with glaucoma, especially those who do not give reliable results on visual field testing, and 2. patients with ocular hypertension. The changes to be looked for are; a) any increase in the size of the cup, b) any decrease in the width of the rim of tissue between the edge of the cup and the edge of the disc, c) the occurrence of small haemorrhages on the disc, d) changes in the course of vessels on the disc.     

Measurement of optic disc compliance by digitized image analysis in the normal monkey eye

PURPOSE: To characterize the compliance of the normal monkey optic disc under conditions of induced short-term fluctuations in intraocular pressure (IOP). METHODS: In 10 monkeys, one eye was compliance tested on three separate days followed by a single test of the contralateral eye (40 compliance tests). In a testing session, the optic disc was imaged at 2 and 47 minutes (baseline time point) after IOP was lowered to 10 mmHg; then at 2, 17, 32, and 47 minutes after IOP was elevated to 45 mmHg; then at 2, 47, and, in some cases, 92 minutes after IOP was lowered back to 10 mmHg. Eight digitized images were analyzed at each time point, yielding two parameters to characterize the position of the disc: the Mean Position of the Disc (MPD) and the Change from MPDBaseline (the value of MPD at a given time point minus the value for MPD at the baseline time point of that testing session). Analysis of variance (ANOVA) testing was used to evaluate the overall effect of IOP on both parameters while taking into account the effects of variability due to different monkeys and repetitions of the test as well as differences between the two eyes of an individual monkey. With the addition of data from 11 compliance tests performed on eight additional monkeys, the overall results were calculated in terms of the mean Change from MPDBaseline at each time point for a total of 51 compliance testing sessions. RESULTS: The mean Change from MPDBaseline was -28 microns (95% confidence interval, -23 to -33 microns) 47 minutes after elevation of IOP. The disc surface returned to its baseline position 92 minutes after IOP was lowered back to 10 mmHg. Elevation of IOP within a compliance test had a significant effect on the position of the optic disc surface (P = 0.0002, ANOVA), as characterized by the parameter Change from MPDBaseline. Neither the difference in the amount of movement between the two eyes of an individual monkey nor the variability within the three repetitions of the test in a given eye was statistically significant. CONCLUSION: Small, reversible (elastic) posterior deformations of the optic disc surface follow acute elevations of IOP in the normal monkey eye. Detection of acute IOP-induced deformations of the optic disc surface may represent a means by which to mechanically test the deeper load-bearing tissues of the optic nerve head.     

Influence of particle size distribution on coarsening

This study has examined the evolution of the particle size distribution and the effect of the initial and transient distributions on coarsening kinetics and the path of evolution. A numerical procedure has been employed to simulate the coarsening process statistically. It was found that the distribution passes through a continuous range of forms from the initial distribution towards the asymptotic state, with initially narrow distributions widening and wide distributions narrowing. Experimental studies using liquid phase sintered Cu-20 Co alloy with different initial distribution widths agreed with the above simulation results qualitatively. The simulated coarsening rate was found to be related to the width and shape of particle size distribution. A rate constant has been derived relating the instantaneous coarsening rate and the transient moments of the distribution. The effect of the initial distribution on coarsening rate was found to be particularly significant in the early stage of coarsening when rapid distribution changes occur. After these early rapid transients but still far from the asymptotic state, the instantaneous coarsening rate was closely related to the instantaneous geometric standard deviation of the distribution.     

Influence of grain size on the hardness of alpha plutonium

The effect of grain size on the hardness of alpha plutonium was measured at temperatures between 77° and 373°K. The observations were: 1) fine-grained metal had the lowest hardness at 373°K, 2) fine-grained metal had the highest hardness at 77°K, and 3) fine-grained metal had the greatest temperature dependence of hardness. At room temperature, fine-grained α-plutonium (1 μm) had a hardness of 235 Dph, whereas coarse-grained metal (2000 μm) had a hardness of 310 Dph. At 373°K fine-grained metal had a hardness of 120 compared to 225 Dph for the coarse-grained metal. At 77°K the hardness values were 505 and 475 Dph, the fine-grained metal being harder at this temperature. The hardness was estimated to be independent of grain size at 140°K. Above 140°K, grain boundaries have a softening effect due to the contribution of grain boundary sliding to deformation.     

煤的粒度对Corex生产指标的影响

Corex工艺用煤的粒度分布是最重要的,它决定了半焦床的透气性和稳定性,因而影响气化炉的生产指标。煤的粒度可以用平均粒度(MPS)和小于6.3mm入炉煤粉比例来监测。降低煤中小于6.3mm煤粉比例和提高煤的平均粒度,都有利于改善气化炉的状况和性能。MPS和小于6.3mm入炉粉率的波动会影响燃料比,并使气化炉炉况不稳定,减少产量。采用工厂数据进行了理论计算,可知煤的粒度对熔融气化炉(MG)料床透气性的影响。采用统计分析方法研究了煤的粒度对Corex生产指标的影响,并尝试建立了入炉煤的粒度与Corex生产指标间的关系。研究结果表明:要使炉况稳定,并改善Corex的性能,要求煤的平均粒度控制在19～22mm范围内,小于6.3mm的粉末比例15%。得出了燃料比与煤的粒度等因素关系的回归方程式。讨论了煤的粉率和平均粒度对Corex生产指标的影响。     

Proliferative diabetic retinopathy with a proliferative membrane that spread anteriorly from the optic disc

The authors report a case of proliferative diabetic retinopathy in which the proliferating membrane spread from the optic disc to the anterior of the eyeball, and did not appear to involve the posterior precortical vitreous pocket.