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At least 271 records · Page 15Linked to original sources
PubMed2004

Repeatability of IOLMaster biometry in children.

AIMS: This study compares the repeatability of IOLMaster (Zeiss, Oberkochen, Germany) axial dimension measurements and conventional ultrasonography in children. METHODS: A series of IOLMaster (partial coherence interferometry, optical pachometry) and Echoscan (US 800, Nidek, Tokyo, Japan) (ultrasound) measurements were taken on 179 Chinese children (mean age, 10.6 +/- 0.8 years) taking part in a longitudinal study of myopia development, and the measurements were repeated on 37 of these subjects. RESULTS: IOLMaster axial length measurements showed better repeatability (95% limits of agreement for repeatability, -0.047 to 0.038 mm) than Echoscan axial length measurements (95% limits of agreement for repeatability, -0.85 to 0.67 mm). IOLMaster anterior chamber depth measurements also showed better repeatability (95% limits of agreement for repeatability, -0.053 to 0.073 mm) than Echoscan anterior chamber depth measurements (95% limits of agreement for repeatability, -0.57 to 0.49 mm). IOLMaster measurements were, on average, slightly larger than Echoscan measurements for axial length (by 0.14 mm) and anterior chamber depth (0.09 mm). CONCLUSION: Partial coherence interferometry techniques, such as that used by IOLMaster, should be considered as the standard technique for axial length measurement in children because they are noninvasive, highly precise, and easy to use.

Biometry↗
PubMed2005

Ametropia and ocular biometry in a U.K. university student population.

PURPOSE: The prevalence of myopia is known to vary with age, ethnicity, level of education, and socioeconomic status, with a high prevalence reported in university students and in people from East Asian countries. This study determines the prevalence of ametropia in a mixed ethnicity U.K. university student population and compares associated ocular biometric measures. METHODS: Refractive error and related ocular component data were collected on 373 first-year U.K. undergraduate students (mean age = 19.55 years +/- 2.99, range = 17-30 years) at the start of the academic year at Aston University, Birmingham, and the University of Bradford, West Yorkshire. The ethnic variation of the students was as follows: white 38.9%, British Asian 58.2%, Chinese 2.1%, and black 0.8%. Noncycloplegic refractive error was measured with an infrared open-field autorefractor, the Shin-Nippon NVision-K 5001 (Shin Nippon, Ryusyo Industrial Co. Ltd, Osaka, Japan). Myopia was defined as a mean spherical equivalent (MSE) less than or equal to -0.50 D. Hyperopia was defined as an MSE greater than or equal to +0.50 D. Axial length, corneal curvature, and anterior chamber depth were measured using the Zeiss IOLMaster (Carl Zeiss, Jena, GmBH). RESULTS: The analysis was carried out only for white and British Asian groups. The overall distribution of refractive error exhibited leptokurtosis, and prevalence levels were similar for white and British Asian (the predominant ethnic group) students across each ametropic group: myopia (50% vs. 53.4%), hyperopia (18.8% vs. 17.3%), and emmetropia (31.2% vs. 29.3%). There were no significant differences in the distribution of ametropia and biometric components between white and British Asian samples. CONCLUSION: The absence of a significant difference in refractive error and ocular components between white and British Asian students exposed to the same educational system is of interest. However, it is clear that a further study incorporating formal epidemiologic methods of analysis is required to address adequately the recent proposal that juvenile myopia develops principally from "myopiagenic" environments and is relatively independent of ethnicity.

Adolescent↗
PubMed2005

Biometry, biometrics, biostatistics, bioinformatics,..., bio-X.

Recent scientific evolutions force us to rethink our profession's position on the scientific map, in relation to our neighboring professions, the ones with which we traditionally have strong collaborative links as well as the newly emerging fields, but also within our own, diverse professional group. We will show that great inspiration can be drawn from our own history, in fact from the early days of the Society. A recent inspiring example has been set by the late Rob Kempton, who died suddenly just months before he was to become President of the International Biometric Society.

Biometry↗
PubMedDate not supplied

Keratometry, biometry and prediction of intraocular lens power in the equine eye.

OBJECTIVE: To determine ocular dimensions (A- and B-scan ultrasound) and corneal curvature (radius of corneal diameter determined in B-scan ultrasound) in the equine eye and to calculate the appropriate dioptric power for a posterior chamber intraocular lens (IOL) necessary to achieve emmetropia in the eyes of horses undergoing lens extraction. ANIMALS: Fourteen clinically normal adult horses of various breeds. Additionally, for comparison, one American Miniature colt foal, and one 2.5-year-old Shire gelding were examined. PROCEDURE: B-scan ultrasound was performed on one eye from each horse. One eye from both the Shire and the American Miniature were examined for comparison. Data from ultrasound (globe measurements and corneal curvature), and the estimated postoperative IOL positions were entered into theoretical IOL formulas (Binkhorst and Retzlaff theoretical formulas) in order to calculate the predicted IOL strength required to achieve emmetropia after lens extraction in horses. RESULTS: Mean axial length of globes was 39.23 mm +/- 1.26 mm, mean preoperative anterior chamber depth (ACD) was 5.63 +/- 0.86 mm, and mean lens thickness was 11.75 +/- 0.80 mm. Predicted postoperative ACD (PACD) was calculated as the ACD plus 50% of the lens thickness. Additionally, PACD 2 mm anterior and 2 mm posterior to the center of the lens were calculated in order to evaluate the effect of IOL position on its required refractive power. Required IOL strength calculated, using the three values for the predicted postoperative ACD, was 29.91 D +/- 2.50, 29 D +/- 2.52 (center of lens); 27.13 D +/- 2.27, 26.33 D +/- 2.20 (2 mm anterior to center of lens); and 33.18 D +/- 2.78, 32.24 D +/- 2.68 (2 mm posterior to center of lens) with the Binkhorst and Retzlaff theoretical formulas, respectively. CONCLUSIONS: An IOL of substantially lower diopter strength than that needed in either dogs or cats is required to achieve emmetropia after lens extraction in adult horses. IOL strength of approximately 30 D, depending on where the IOL ultimately comes to rest, will probably be required.

Animals↗
PubMedDate not supplied

Ocular biometry in the adult anesthetized ferret (Mustela putorius furo).

A total of 44 eyes of 22 ferrets were examined by B-mode ultrasonography. Four dimensions were measured: the distance from the corneal surface to the anterior lens surface (M1), the axial lens thickness (M2), the distance from the posterior lens surface to the retina (M3) and the distance from the anterior cornea to the retina (M4). The values obtained were (mean, standard deviation, range): M1: 1.31 +/- 0.16 mm (1-1.7); M2: 3.42 +/- 0.15 mm (3.2-3.7); M3: 2.26 +/- 0.11 mm (2.1-2.5); M4: 7 +/- 0.24 mm (6.4-7.7). To our knowledge this is the first description of ocular biometric measurement in the ferret. These values show little variability of ocular dimensions in ferrets.

Animals↗
PubMed2005

Growth patterns of fresh human crystalline lenses measured by in vitro photographic biometry.

The purpose of the study was to demonstrate and evaluate the use of digital-image photography to measure the central thickness and equatorial diameter of whole fresh human crystalline lenses free of all zonular attachments. Forty-one human donor postmortem intact clear crystalline lenses, with a mean age of 28.5 +/- 16.4 years, were obtained by the contributing eye banks. The lenses were removed by the eye bank and shipped in Optisol-GS, a physiologic preservative storage medium, at 7 degrees C. The lenses were stored at the same temperature and in the same preservative throughout this study. This medium has been demonstrated to maintain the morphometric characteristics of epithelial cells. After freeing the lenses of all residual zonular attachments, digital photographs were obtained within an average of 20.9 +/- 13.4 h after death. The digital images were used to determine the central thickness and equatorial diameter of the crystalline lenses. By carefully calibrating the digital images and maintaining the lenses in physiological storage medium, reliable dimensional measurements were obtained. The dimensions for central thickness for each lens were compared to published, age-matched lenses, measured in vivo, and were found to duplicate these in vivo measurements reliably.

Adolescent↗
PubMed2005

Accuracy of ultrasound biometry in the prediction of macrosomia: a systematic quantitative review.

OBJECTIVE: To determine the accuracy of ultrasonographically estimated fetal weight (EFW) and abdominal circumference (AC) in the prediction of macrosomia. DESIGN: Systematic quantitative review. METHODS: Studies were identified without language restrictions from MEDLINE (1966-2003), EMBASE (1980-2003), Cochrane Library (2003:4), SCISEARCH (1974-2003) and manual searching of bibliographies of known primary and review articles. Studies were selected if accuracy of ultrasonographically EFW or AC was evaluated for predicting macrosomia using birthweight as the reference standard. Data were extracted on study characteristics, quality and accuracy. Data were pooled to produce summary receiver operating characteristic curves (sROC) for studies with various test thresholds. Summary likelihood ratios for positive (LR+) and negative (LR-) test results were generated for an EFW of 4000 g and an AC of 36 cm for predicting birthweight of over 4000 g. MAIN OUTCOME MEASURES: Birthweight over various thresholds. RESULTS: There were 36 primary articles consisting of 63 accuracy studies (51 evaluating the accuracy of EFW, and 12 accuracy of fetal AC), including a total of 19,117 women. The sROC area for EFW was not different from the area for fetal AC (0.87 vs 0.85, P= 0.91). For predicting a birthweight of over 4000 g, the summary LRs were 5.7 (95% CI: 4.3 to 7.6) for a positive test and 0.48 (95% CI: 0.38 to 0.60) for a negative test, using Hadlock's method of ultrasonographically estimating fetal weight. For ultrasound fetal AC of 36 cm, the respective LRs for predicting a birthweight over 4000 g were 6.9 (95% CI: 5.2 to 9.0) and 0.37 (0.30-0.45). CONCLUSION: There is no difference in accuracy between ultrasonographically EFW and AC in the prediction of a macrosomic baby at birth. A positive test result is more accurate for ruling in macrosomia than a negative test result for ruling it out.

Abdomen↗
PubMed1994

Biometry in X linked megalocornea: pathognomonic findings.

Biometric study in a series of 11 affected males provides characteristic findings. The patients present with a large cornea with short radius, very deep anterior chamber depth (AC depth) exceeding the normal mean value of plus 2 SD, and a short vitreous length. Calculation of the postlimbal depth, a method applied in this study to obtain information about positioning of the iris and the lens, reveals a posterior positioning of the iris and lens. The posterior positioning of the iris and lens was proved to occur at the expense of the vitreous. The importance of biometric data for diagnosis and for differential diagnosis in primary infantile glaucoma and other diseases with megalocornea is discussed.

Adolescent↗
PubMedDate not supplied

Biometry of the fetal heart between 10 and 17 weeks of gestation.

OBJECTIVES: Assessment of the dimensions of the cardiac chambers and the great arteries in the human fetus may be helpful in the prenatal diagnosis of congenital heart disease. The purpose of this prospective cross-sectional study was to compile normative data in fetal cardiac measurements in early pregnancy. The structure of the fetal heart was examined in 136 normal singleton fetuses between 10 and 17 weeks of gestation. METHODS: The transversal heart diameter, both ventricular dimensions, interventricular septal thickness, heart area, heart circumference, thoracic diameter, thoracic circumference and thoracic area were measured in the four-chamber view during diastole. Diameters of the pulmonary trunk and ascending aorta were obtained in the short axis and long axis view during systole. Ultrasound examinations were performed with a 5.0-MHz transvaginal and/or transabdominal phased-array sector scanner. RESULTS: The four-chamber view and the cross-over of the pulmonary artery and the aorta were adequately visualized in 44% of the fetuses at 10 weeks of gestation, in 75% at 11 weeks of gestation, in 93% at 12 weeks of gestation and in 100% of the fetuses at 13-17 weeks of gestation. Before 14 weeks of gestation transvaginal sonography was superior to the transabdominal sonography in visualization of the fetal heart and great arteries. After 14 weeks of gestation transabdominal sonography accurately demonstrated the structure of the fetal heart. The ratio of right and left ventricle (RV/LV) and the ratio of the pulmonary trunk and aorta (PT/AO) were constant during this period of gestation (approximately 1.00 and 1. 10, respectively). The ratio of the cardiac and thoracic area showed only a slight increase with advancing gestational age, but with significant correlation. The fetal heart rate showed a slow decrease from 167 to 150 bpm in this period of gestation. The transversal heart diameter, both ventricular dimensions, interventricular septal thickness, heart area, cardiothoracic diameter ratio, aortic diameter and the pulmonary trunk diameter showed a highly significant linear correlation to the gestational age and the biparietal diameter. CONCLUSION: The advancing quality of ultrasound images allows fetal echocardiography in the first and early second trimester. Our normative data could be the basis of studying the development of cardiac structures in congenital heart disease and it might be helpful in the detection of some congenital heart defects in early pregnancy.

Aorta↗
PubMedDate not supplied

Early transvaginal biometry of fetal orbits: a cross-sectional study.

OBJECTIVE: To construct nomograms of orbital diameters in early pregnancy by transvaginal sonography. DESIGN: A prospective cross-sectional study. METHODS: The study was performed on 923 consecutive normal singleton pregnancies from 10 to 16 weeks of gestation, using transvaginal high-resolution ultrasound technique. The interocular distance (IOD), binocular distance (BOD), as well as the orbital diameter (OD) at each gestational age (GA, days), were recorded. The distribution of the residuals for the different orbital measurements are also described. RESULTS: The increase in each of the ocular parameters studied could be accurately described by a linear model. The regression equation for orbital measurements as a function of GA was: for IOD, y = 0.153 GA (days) - 6.73 (r2 = 0.82); for BOD, y = 0.387 GA (days) - 16.85 (r2 = 0.80), and for OD, y = 0.132 GA (days) - 6.435 (r2 = 0.79). IOD and OD demonstrate a normal distribution of the residuals with uniform variance. CONCLUSION: The presented data obtained in early pregnancy by transvaginal scan offer normative measurements of the orbital diameter which may be useful in the prenatal diagnosis of congenital syndromes that include, among other manifestations, orbit maldevelopment and growth disturbances.

Adult↗