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PubMed2003

[Difficult cases in biometry measurement].

A few problems have not yet been resolved concerning intraocular lens (IOL) power calculation in difficult cases. Patients can be divided into three groups: Group 1, patients with no previous ocular surgery but with unusual anatomy (staphyloma, high hyperopic eyes, etc.); Group 2, patients with previous surgery except refractive surgery; Group 3, patients with previous refractive surgery. Various techniques must be used to increase the accuracy of IOL calculation. B-mode biometry and optical coherence tomography are suitable tools to increase the accuracy of axial length measurement. Computerized videokeratography can be helpful. However, the most difficult cases seem to be those in Group 3.

Biometry↗

PubMed1992

Effects of different ocular fixation conditions on A-scan ultrasound biometry measurements.

A-scan readings must be taken along the visual axis for accurate axial length measurement. Various fixation targets, which ideally should not induce accommodation, are used to limit eye movements. In this study results using the Humphrey biometer under different fixation conditions were compared to establish the most suitable target. We also investigated corneal applanation effects by comparing optical and ultrasonic measurements of anterior chamber depth. We examined 12 randomly selected normal eyes of 12 young subjects. Three A-scans were recorded for each of five fixation conditions: spotlight at 6 m; Snellen letter at 6 m; solid probe's built-in green fixation target; Snellen letter at 6 m viewed through a -4.00 DS lens; spotlight at 6 m under cycloplegia (the comparison condition). Variability 'within' each fixation condition, estimated by the standard deviation for each subject, was equal throughout the 12 subjects for each fixation condition. Also variation was independent of size of the ocular dimension. The good agreement between the comparison condition and optical anterior chamber depth measurements indicated that the solid probe produced little applanation. Differences 'between' fixation conditions were investigated. It was concluded that a spotlight or letter at 6 m provides a suitable fixation target for biometry. Built-in fixation targets can produce significant errors.

Adult↗

PubMed1992

[Fetal echocardiography. II. Biometry of the normal fetal heart].

Normal fetal hearth biometry is analyzed by echocardiography in 80 pregnant women with 20 and 40 gestational weeks. Intraventricular septum, aorta, left and right ventricular dimensions were obtained. All dimensions showing progression with gestational age.

Biometry↗

PubMed1991

[Ultrasonic biometry of the fetal kidney].

Renal biometry of the fetus was carried out on 1200 women when exogenous difference between renal and surrounding tissue became distinct. Three dimensions of the kidney were measured at two mutually performed perpendicular scans. In our study it was established that the ratio between the circumference of the kidney and the abdominal circumference was a constant, preserving itself during the whole pregnancy. Establishment of this process presented diagnostic criteria for fetal hypotrophy as well as for anomalies in the development of the kidney. The three parameters as well as the estimated by them volume of the kidney could be presented as dynamic curves, rather similar in their course with the curves of BPD and the abdominal circumference. Prognosis of the fetal weight was made on the basis of the volume of the kidney by the formula W = 125, 1689 + (0.2008 X V), as the exactness of the method was commensurable with the precision of the popular combined biometric formulas, although only one parameter was used. The ratio the pelvis:kidney was of interest as well, since it differed from that of the grown up persons and it was from 1:3 to 1:4 within the fetal norm. The transverse size of pelvis at least over 15 mm suggested obstructive uropathy and hydronephrosis. There was no statistically significant difference in the biometric parameters of the right and left kidney of the fetus in our study.

Biometry↗

PubMed1989

Fetal biometry as a screening tool for the detection of chromosomally abnormal pregnancies.

Recent studies suggest that fetal biometry may allow recognition of pregnancies at risk for Down syndrome. Second-trimester biparietal diameter (BPD)/femur length and observed-to-expected femur length ratios were examined in 48 chromosomally abnormal fetuses and compared with those of a control population composed of both low-risk patients (maternal age less than 35 years) and high-risk patients (maternal age 35 years or more). Biparietal diameter/femur length ratio correctly identified 18% of Down syndrome pregnancies with a positive predictive value of one in 169 and a false-positive rate of only 4%. When trisomies 21, 18, and 13 were considered collectively, a sensitivity of 29% and a predictive value of one in 78 were achieved, with no increase in the false-positive rate (4%). Observed-to-expected femur length ratio was less valuable in detecting chromosomally abnormal fetuses. These data suggest that the BPD/femur length ratio holds promise as a screening tool for the antenatal detection of fetal chromosomal abnormalities. Although encouraging, extrapolation of these results to other centers is not recommended without independent verification.

Biometry↗

PubMed1989

The role of biometry in the training of medical informaticians.

Medical informatics and medical biometry, as well as the medical biometrician's and medical informatician's fields of activity, overlap significantly. The affinity between the two disciplines can be illustrated by a comparison of the definitions of both disciplines, by examples of research projects for which the application of methods from both fields is necessary in order to complete the project successfully, and by an analysis of the professional fields of medical informatics graduates working in their occupation. Therefore, a stronger integration of both disciplines is advocated.

Biometry↗

PubMed1985

[The value of current echographic parameters in fetal biometry].

A review of current literature concerning developments of new parameters in fetal biometry is presented. To be sure, these parameters are very useful for detection of fetal malformations but outside of femoral length they do not contribute more valuable information than the already accepted parameters for determination of gestational age or detection of disorders of fetal growth.

Biometry↗

PubMed1985

Biometry and medical statistics.

The "biometric school" founded by K. Pearson, F. Galton, and W. F. R. Weldon was concerned especially with heredity and variation, and between the wars "biometry" was not widely used as a general term for quantitative biology. The foundation of the Biometric Society encouraged this wider usage, and medical and biological statistics were seen to share a common methodology. In recent years, medical statistics has developed more rapidly, and this growth has been reflected in the contents of Biometrics. The author stresses the essential unity of the subject, the central core of which is the application of statistics in the life sciences. The Society should encourage contact with those workers in quantitative biology who are outside this central tradition.

Biometry↗

PubMed1983

[Fetal echocardiography during the 2nd half of pregnancy. Biometry and functional approach].

Fetal cardiac biometry was conducted in the TM mode, after real time anatomical outlining of the plane of the four cardiac cavities, on 48 recordings of supposedly normal pregnancies of 23 to 39 weeks of amenorrhoea. Ten measurements were made for each patient, in an immediately subvalvular plane perpendicular to the septum (dimensions of the two ventricular cavities, of the wall of the two ventricles, and of the septum, in diastole and systole respectively). Functional results derived from this data showed that the difference between diastolic and systolic values for ventricular diameters increased with term, the ratio of the diastolic diameter of the right ventricle (RV) to that of the left ventricle (LV) was a constant: 1.23 +/- 0.12, and the size of the RV was always superior to that of the LV (+ + +). Alson noted was that percentage shortening of the LV was superior to that of the RV, and mean percentage thickenings of the RV and septum were inferior to that of the LV. A further observation was that interpretation of the kinetic of the septum requires precise knowledge of the plane of the section in relation to "the pivot point".

Biometry↗

PubMedDate not supplied

[Renal study protocol with ultrasonography: biometry and incidence of disease].

The present study establishes the size of the kidneys in adult males and females according to three age groups, under 30, 30 to 60, and over 60, in our community. To this end, morphologically normal kidneys were studied, considering four diameters: longitudinal (L), antero-posterior (AP), transverse (T) and cortical (D). We found that renal size, in all diameters, was larger in males and females, and the left one larger than the right one. The study include 522 kidneys, from a total of 247 subjects. Apart from renal biometry, the incidence of disease was also recorded. Ten different possibilities were included in the picture: 1) Normal (N); 2) Cysts (C); 3) Lithiasis (L); 4) Tumour (T); 5) Pyelonephritis (PN); 6) Acute Focal Nephritis (AFN); 7) Hydronephrosis (HN): 8) Double Excretory System (DES): 9) Abscesses (A); and 10) ther (O). The incidence of disease is maximal in subjects over 60, with predominance of women and left kidney; most frequent changes were cysts and pyelonephritis. Of the three age groups, those under 30 had a mean age of 22.36 years, 85% being between 18 and 30 years; in the intermediate group, 30 to 60 years, mean age was 48.40 with 65% between 45 and 60; in the over 60 group, mean age was 68.67 with 70% between 61 and 70 years of age.

Adolescent↗

PubMed2003

Revisiting first-trimester fetal biometry.

INTRODUCTION: Although advances in ultrasound have facilitated the diagnosis of fetal abnormalities in the first trimester, fetal biometry at this stage of pregnancy remains underused in prenatal diagnosis. We hypothesized that charts which directly correlate measurements to crown-rump length (CRL) could be more accurate than those based on gestational age (GA) derived from CRL measurement. The aim of this study was to construct CRL-based biometric charts. METHODS: Measurements of biparietal diameter (BPD), head circumference (HC) and abdominal circumference (AC) were prospectively collected from 939 normal singleton fetuses. Charts and predictive equations were constructed from data obtained from pregnancies in which the CRL was between 45 and 84 mm and for which the outcome was normal. RESULTS: Measurements of BPD, HC and AC from 880 fetuses who met the criteria were correlated with CRL and used to construct charts and predictive equations. The standard error of estimates using CRL was significantly lower than that using GA in all cases. DISCUSSION: First-trimester growth charts and predictive equations based on CRL instead of GA are more accurate. They might have a role in quality control of first-trimester ultrasound examination and may help in the diagnosis of fetal conditions that involve early growth abnormalities.

Abdomen↗

PubMed1975

[Ultrasonic biometry and oculopression].

The changes of the intraocular distances provoked by oculopression (10 min, 40 mm HG) were explored by ultrasonic biometry. Immediately after removing the oculopressor, a flattening of the anterior chamber and a deepening of the vitreous cavity occurred. The maximal deepening of the anterior chamber together with the shortening of the vitreous axis appeared 9 min after oculopression on an average. The causes of the predominance of the initial lengthening (0.24 mm on an average) and of the following shortening (0.16 mm on an average) of the vitreous cavity compared with contrary changes of the anterior chamber are discussed.

Adult↗

PubMed1985

Sonographic biometry in obstructive uropathy of children: preoperative diagnosis and postoperative monitoring.

Renal sonography was performed in 92 children with obstructive uropathy or vesicoureteral reflux preoperatively and at follow-up. Renal volume and the anteroposterior diameter of the renal pelvis proved to be the most reliable morphometric criteria for objective sonographic staging and follow-up of urinary tract obstruction. If transient obstruction occurred after uncomplicated antireflux ureterovesico-plasties (n = 41), it lasted at most 4 weeks. Kidneys with transient postoperative ureterovesical junction obstruction (n = 21) reverted to normal sonographic pattern within 4 weeks following ureteral reimplantation. In cases of ureteropelvic junction obstruction (n = 30), it took up to 6 months for the majority of kidneys to present almost normal sonographic findings. Sonographic biometry and the knowledge about the uncomplicated postoperative course render postsurgical monitoring easier and more reliable.

Adolescent↗

PubMed2002

Biometry of the radial head: biomechanical implications in pronation and supination.

The aim of this study was to perform biometry of the proximal extremity of the radius and to characterize the shape of the radial head. Knowledge of the size and shape of the radial head is necessary for the creation of a radial head prosthesis that is anatomically and biomechanically correct. Twenty-seven measurements, focused on the proximal extremity, were done on 96 radii. The shape of the radial head was determined by the difference between the maximum diameter and the minimum diameter. We considered the shape to be circular when the difference was less than 1 mm, and elliptical when the difference was greater than 1 mm. The shape of the radial head was compared with the neck/diaphysis angle. Fifty-seven percent of radial heads were elliptical and 43% were circular. When the head was elliptical the maximum diameter was 22 mm +/-2.9 and the minimum diameter was 20 mm +/-2.8 ( P<0.001). When the head was circular the maximum diameter was 21.2 mm +/-2.4 and the minimum diameter was 20.4 mm +/-2.4 ( P<0.14). The angle between the neck and the diaphysis varied with regard to the shape of the radial head. It was 166.75 degrees +/-3 for the circular heads and 168.62 degrees +/-3.2 for the elliptical heads ( P<0.01). The biomechanics of the circular shape and the elliptical shape are different, involving an adaptation of the angle between the neck and the radial diaphysis. This difference must be taken in consideration in the design of a radial head prosthesis.

Anthropometry↗

PubMedDate not supplied

[Fetal biometry: review and application of sex determination].

Diagnostic ultrasound was introduced in the practice of obstetrics through its ability to measure accurately the biparietal (DBP) diameter of the foetus. The development of bidimensional and grey tone images expanded the possibility of fetal biometry. One of its most important uses is the estimation of gestational age. A knowledge of foetal age is necessary to interpret the results of most of the investigations currently performed during pregnancy. Different fetal dimensions increase with age at different rates according to the period of gestation. During the embryonic period, the crown-rump length gives a very good estimation of age within 4-6 days for twice the standard deviation. Later on, because of the curvature of the fetus, the age is estimated with the DBP. The accuracy diminishes with the slowing down of fetal growth, from 12 weeks onwards, when twice the standard deviation of the age estimate may be as long as 2 weeks. When DBP is no longer reliable in determining age, femur length is measured being more reliable for that purpose at least till 24 weeks. A very early assessment of foetal age reduces the risk of errors in estimating the duration of pregnancy and is important to detect early growth retardation (IUGR); this is usually symmetric, i.e. affecting all fetal parts (versus asymmetrical or late IUGR where trunk growth is first involved). Fetal weight can be estimated by fetal parts measurements. A formula was derived as long as twenty years ago but not all authorities agree on any measuring technique as evidenced by the many different formulas proposed--a sign that no very satisfactory one yet exists.(ABSTRACT TRUNCATED AT 250 WORDS)

Anthropometry↗

PubMed1993

Clinical disc biometry in early glaucoma.

PURPOSE: To assess the potential of a clinical method of optic disc measurement in the detection of early neuroretinal rim loss in glaucoma. METHODS: A method of disc biometry based on indirect ophthalmoscopy was used to estimate disc and neuroretinal rim areas in 81 ocular hypertensive eyes of 43 patients and in 28 fellow eyes with normal visual fields of patients with unilateral visual field loss from primary open-angle glaucoma. The results were compared with those from age-matched visually normal patients. RESULTS: Neuroretinal rim area was significantly smaller in both hypertensive and fellow eye groups compared with controls (P < 0.0001; P = 0.0009). Disc area also was smaller in both groups (P = 0.0034; P = 0.046); however, this was inadequate to explain the differences in rim area, which, when corrected for disc size, were still highly significant (P < 0.0001; P = 0.0001). CONCLUSION: The differences in neuroretinal rim area observed are likely to indicate that a proportion of the eyes studied had suffered a reduction of neuroretinal rim area, which was measurable by this method at a stage before the development of demonstrable visual field loss.

Glaucoma, Open-Angle↗

PubMed1992

Clinical comparison of automated and manual keratometry in pre-operative ocular biometry.

Corneal measurements, using the manual (Topcon OM-4) and automated (Canon RK-1) keratometers was performed on 104 eyes of 104 patients undergoing cataract and implant surgery to assess the role of automated keratometry in pre-operative ocular biometry. Four eyes of four patients were excluded from statistical analyses for various reasons. The time taken to perform automated keratometry was a mean of 61 (SD 21) seconds compared to 205 (SD 37) seconds for manual keratometry; the difference was statistically significant (p < 0.001). In terms of the various keratometry values compared, mean K (corneal refractive power), flattest K, steepest K, astigmatism and the axis of astigmatism, 65% to 75% of the cases on automated keratometry were within 0.26 dioptres or 11 degrees of manually determined values; the difference was statistically significant (p < 0.001). Although automated keratometry was significantly quicker than manual keratometry, we continue to use manual keratometry values for intraocular lens power calculations as the accuracy demonstrated by automated keratometry was considered inadequate for this purpose.

Aged↗

PubMed1994

Ocular biometry in pre-term infants without retinopathy of prematurity.

Serial ocular A-scan ultrasound biometry was performed on 100 pre-term infants (less than 32 weeks gestation and/or less than 1500 g) who did not show features of retinopathy of prematurity (ROP) during a screening programme. Axial length increased from 15.38 +/- 0.25 mm at 33 weeks post-menstrual age to 16.88 +/- 0.59 mm at 41 weeks (rate of growth 0.18 mm/week, r = 0.99). The rate of growth appeared to slow down after 40 weeks (term) to 3 months post-term. Male infants had longer eyes and a greater rate of growth than female infants. Axial length (AL) was significantly correlated with birth weight, biparietal and occipito-frontal diameter in the weeks after birth. Between weeks 33 and 41, the anterior chamber depth (ACD) increased from 1.92 +/- 0.13 mm to 2.43 +/- 0.18 mm, and lens thickness (LT) increased from 3.82 +/- 0.33 mm to 3.90 +/- 0.13 mm. The largest percentage growth between weeks 33 and 41 occurred in ACD (22%), followed by vitreal length (10%), AL (9%) and LT (2%). These data will help in future studies on the role which ROP plays in the development of ocular growth.

Anthropometry↗