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At least 199 records · Page 11Linked to original sources

PubMed1980

[Ultrasonic biometry for foetal weight determination (author's transl)].

A new formula has been derived from computer-aided analysis for predictive calculation of foetal weight. Biparietal diameter and mean thorax diameter were the parameters for measurement, while the truncus was additionally included for another method by which even higher demands could be met. Weight determination proper was based on a practicable vanishing point diagram (nomogram). -- A critical appraisal is made of the methods previously used for weight forecasting on the basis of ultrasonic biometry. The authors' own approach is described in great detail and for convenient check-up by means of mathematical tables and graphs. It is claimed to give better results, particularly in marginal areas of foetal development, such as hypertrophy and/or macrosomia in concomitance with diabetes mellitus or retardation. -- Data published by other authors were recalculated, with the view to producing hard evidence to the superiority of the new formula.

Anthropometry↗

PubMed1994

[A CT study of the relation between ocular axial biometry and refraction].

Ocular biometry in 255 eyes (131 subjects) with CT scan revealed that the length of the antero-posterior axis was 23.63 +/- 0.92 mm in hyperopia, 24.62 +/- 0.38 mm in emmetropia and 26.68 +/- 0.75 mm in myopia, and the length of the horizontal transverse axis was correspondingly 24.61 +/- 0.53 mm, 24.91 +/- 0.37 mm and 25.12 +/- 0.73 mm. There were significant differences among groups of different refractions, and the axial length increased with the severity of myopia. It was evident that refractive errors were chiefly caused by the varying axial lengths. The authors propose the parameter of the ocular diametrical ratio which is the ratio of the anteroposterior axis to the horizontal transverse axis, and accordingly hyperopia has a ratio under 1, myopia a ratio over 1 and an emmetropic eye is apparently spherical with the ratio in the vicinity of 1. The authors point out that the refractive state is determined by the ocular diametrical ratio.

Adult↗

PubMed1995

Reference charts of foetal biometry in Asians.

OBJECTIVES: To construct reference ranges for foetal biometry measurements of biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), humerus length (HL) and mandible length (ML) for the Asian population in Singapore. DESIGN: A prospective, cross-sectional study. SETTING: The obstetric ultrasound services and the labour ward of the department of Obstetrics and Gynaecology in Singapore General Hospital. SUBJECTS: The foetuses of 6,374 women whose delivery date was within 2 weeks of their estimated date of delivery (EDD) as calculated from the last menstrual period. METHOD: During the period August 1, 1989 and December 31, 1993, 17,005 obstetric ultrasound scans were retrieved from the computerised database. These ultrasound scans were cross-referenced with the delivery database and the earliest ultrasound scan of 6,374 women who delivered within 2 weeks of their EDD were retrieved for analysis. Different growth models were fitted using regression analysis to estimate the mean and standard deviations as functions of gestational age. Centiles were then derived after confirming a normal distribution of measurements at each gestation. RESULTS: A total of 6,131 measurements of the BPD, 6,117 measurements of the HC, 6,017 measurements of the AC, 6,078 measurements of the FL, 2,863 measurements of the HL and 2,029 measurements of the ML were obtained. Regression analysis using the linear-cubic formula was used to model the mean values; a separate linear regression analysis was used to model the standard deviations. CONCLUSION: These are the regressed reference charts from 6,374 Asian foetuses using parametric analysis of cross-sectional data. The authors encourage their use in Asian foetuses.

Anthropometry↗

PubMed1997

Submicrometer precision biometry of the anterior segment of the human eye.

PURPOSE: To demonstrate the feasibility of measuring the anterior structures of the human eye by partial coherence interferometry and to determine its precision for eyes under normal and cycloplegic conditions. METHODS: The dual-beam version of partial coherence interferometry, a recently developed noninvasive optical ranging technique, enables high resolution measurements of several intraocular distances with unprecedented precision. A modified, more sensitive scanning version of this technique was used to assess the central and peripheral corneal thickness, the anterior chamber depth, and the lens thickness of 20 healthy, emmetropic to moderately myopic eyes. Furthermore the anterior structures of three eyes were measured under cycloplegia (1% cyclopentolate) to investigate the influence on the precision of this technique after suppression of residual accommodations. RESULTS: The mean geometric precision (standard deviation) of the measurement of the central corneal thickness was 0.29 micron (range, 0.22 micron to 0.38 micron) and 0.43 micron (range, 0.27 micron to 0.56 micron) for the peripheral corneal thickness at a distance 2 mm from its apex. The precision for measuring the anterior chamber depth and the lens thickness for fixation at infinity was 8.7 microns (range, 3.9 microns to 16.8 microns) and 8.9 microns (rang, 2.9 microns to 14.4 microns) for noncycloplegic eyes and 1.9 microns (range, 1.7 microns to 2 microns) and 1.4 microns (range, 0.7 micron to 1.8 microns) for cycloplegic eyes, respectively. CONCLUSIONS: The dual-beam partial coherence interferometry enables fast, noninvasive, submicrometer precision biometry of the anterior segment of the eye. The precision of determining the anterior chamber depth and the lens thickness is more than one order of magnitude better than that of the currently used ultrasound and optical techniques, and it can be improved by a factor of 5 by using cycloplegia.

Adult↗

PubMed1955