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At least 775 records · Page 43Linked to original sources
PubMed1991

Secondary IOL power calculation. A comparison of an optical and a biometric method.

In 40 aphakic eyes undergoing secondary IOL implantation, the axial length was calculated optically as well as measured by ultrasound, and the two methods of axial length determination were compared to evaluate the accuracy in the calculation of secondary IOL power. The mean refractive prediction error (+/- SD) was 0.18 diopters (+/- 0.96) and -0.37 diopters (+/- 0.83) using the optical and the biometric method, respectively. The difference in mean value was significant, whereas the variation around the mean value was not found to be significantly different between the two methods. A calculated axial length may offer a valuable alternative to biometry in the aphakic eye, increasing the accuracy of secondary IOL power calculation.

Adolescent↗
PubMed1991

[Accuracy of ultrasound measurements of the axial length of the eye].

Ultrasonic assessment of the axial length of the eye provides important baseline data for the calculation of the dioptric power of an artificial intraocular lens. The accuracy of ultrasonic biometry performed by an OPHTASCAN B apparatus is discussed based on evaluation of a group of repeated measurements of the axial length and depth of the anterior chamber in 592 bulbi.

Adult↗
PubMed1983

[Tomodensitometry of the humeral distal extremity. Morphologic and biometric study of the pillars].

Biometry by computerized tomography on osseous series has not yet been applied in physical anthropology. I performed computed tomographical cross-sections on nine distal human humeri, every three millimetres, up to five centimetres of their length. The bi-epicondylar width was the reference level to compare the bones. I took several measurements at each level for each bone, and each area was calculated. The results confirmed our previous data on dry bones. Many reproducible and valuable measurements were possible, the accuracy of several was increased, and new measurements were defined. The morphological analysis of density measurements added new data. The osseous areas were easily integrated. This method which does not alter bones is precise and important in osteological studies in modern and paleo-anthropological primatology.

Biometry↗
PubMed1995

Antenatal ultrasound and fetal Doppler. Diagnosis and outcome in intrauterine growth retardation.

Advances in ultrasonographic biometry and fetal Doppler technology enhance our ability to detect the presence of fetal growth retardation, expand our understanding of its pathophysiology, and improve the ability to predict certain outcome parameters. Further refinement of these methods will allow better definition of IUGR as well as a means to more accurately direct perinatal resources. As causes of fetal growth retardation become more precisely defined, improvements in outcome are likely for certain subsets of those populations.

Biometry↗
PubMedDate not supplied

[Biometrical analysis in the radiobiology works of N. V. Luchnik].

The contribution of the famous Russian geneticist and biophysicist N. V. Luchnik into biometrical analysis of radiobiological data is discussed. His works on radiation mortality of mice and the process of post-radiation repair of chromosome aberrations are thoroughly observed. The conclusion of necessity to develop biometrical analysis as separate part of biometry is made.

Animals↗
PubMed1996

The correlation of corneal refractive power, axial length, and the refractive power of the emmetropizing intraocular lens in cataractous eyes.

Ultrasound biometry was done for 400 cases of cataract. The posterior-chamber lens power was found to be 18.2 +/- 4.26 D; the corneal refractive power, 43.78 +/- 1.86 D; and the axial length of the globe, 23.57 +/- 1.57 mm. The correlation between the refractive power of the cornea and the axial length shows the following physiological mechanism: (1) in hypermetropia an increase in corneal refractive power occurs in parallel with an increase in axial length; (b) in myopia an increase in axial length is compensated by a decrease in corneal refractive power, with both of the aforementioned conditions aiming at achieving emmetropia; and (c) patients with axial myopia either react in the form of condition b (state of compensation) or show an increase in corneal refractive power in association with an increase in axial length (state of decompensation).

Biometry↗
PubMed1998

Experimental implantation of posterior chamber prototype intraocular lenses for the feline eye.

OBJECTIVE: To measure postoperative anterior chamber depth (ACD), corneal curvature, and refractive state of feline eyes after lens removal and implantation of a prosthetic intraocular lens (IOL) and determine appropriate IOL use in cats. ANIMALS: 8 clinically normal adult cats. PROCEDURE: A-scan ultrasonic biometry, keratometry, and streak retinoscopy were performed on both eyes of each cat before and after lens removal and implantation of a prosthetic IOL. Three diopter (D) IOL strengths were used: 48, 51, and 60 D. Measurements were recorded for 12 weeks after surgery. RESULTS: IOL were well tolerated by cats, with no serious complications attributable to implantation or presence of the IOL. The ACD was significantly greater after (8.30 mm) than before (4.97 mm) surgery; however, it became slightly more shallow during the 4 weeks after surgery, suggesting that the IOL shifted anteriorly in the eye. Significant difference in corneal curvature was not detected before or after surgery among eyes with various IOL. Twelve weeks after surgery, eyes with 48-, 51-, and 60-D IOL had mean +/- SD refractive state of +2.1 +/- 0.49, +0.42 +/- 0.20, and -2.6 +/- 0.78 D, respectively. Linear regression analysis of refractive state on IOL power for all eyes at 12 weeks after surgery predicted that +52.8-D IOL was necessary to best approximate emmetropia in these cats. CONCLUSION AND CLINICAL RELEVANCE: IOL of substantially higher diopter strength than that needed in dogs was required to achieve emmetropia after lens extraction in cats. A 52- to 53-D IOL is required to correct feline eyes to near emmetropia after lens removal.

Animals↗
PubMed2002

Near-work activity, night-lights, and myopia in the Singapore-China study.

OBJECTIVE: To investigate the relationship among near-work activity, night-lights, and myopia in schoolchildren in Singapore and Xiamen, China. METHODS: The refractive error and ocular dimensions of 957 Chinese schoolchildren aged 7 to 9 years in Singapore and Xiamen, China, were determined using cycloplegic autorefraction and A-scan ultrasound biometry. Information on near-work activity (number of books read per week, reading in hours per day) and night-light use before age 2 years was obtained. RESULTS: The prevalence rate of myopia was 36.7% (95% confidence interval [CI], 33.0%-40.3%) in Singapore and 18.5% (95% CI, 14.0%-23.1%) in Xiamen, China. The crude odds ratio (OR) of higher myopia (at least -3.0 diopters) for children who read more than 2 books per week was 3.50 (95% CI, 2.15-5.70). In a multivariate logistic regression model, the OR of higher myopia for children who read more was 2.81 (95% CI, 1.69-4.69), adjusted for age, night-light use, parental myopia, and country, whereas there was no association between night-light use before age 2 years and higher myopia (OR, 1.54; 95% CI, 0.92-2.58), after controlling for age, books read per week, parental myopia, and country. MAIN OUTCOME MEASURES: The ORs of higher myopia for children who read more and children who are exposed to night-lights before age 2 years. CONCLUSIONS: Reading (number of books per week) may be associated with higher myopia in Chinese schoolchildren. However, night-light use does not seem to be related to higher myopia.

Child↗
PubMed2006

Ultrasound biomicroscopy in asymmetric pigment dispersion syndrome and pigmentary glaucoma.

OBJECTIVE: To identify differences in anterior chamber anatomy among patients with asymmetric pigment dispersion syndrome and no other discernible cause for the asymmetry. METHODS: Ultrasound biomicroscopy and A-scan biometry were performed on both eyes of 13 patients with asymmetric pigment dispersion syndrome without a known cause for asymmetric involvement. A radial perpendicular image in the horizontal temporal meridian detailing the scleral spur, angle anatomy, and iris configuration was obtained for each eye by 2 examiners. RESULTS: There were no differences in lens thickness (P = .33), refractive error (P = .84), or axial length (P = .99) between more and less affected eyes. However, the mean +/- SD iris concavity (P<.001), iris-lens contact distance (P = .02), and distance from the scleral spur to the iris insertion (0.42 +/- 0.11 vs 0.29 +/- 0.06 mm) (P = .002) were greater in the more affected eye of each patient. CONCLUSION: A more posterior iris insertion predisposes to the phenotypic expression of pigment dispersion syndrome.

Adult↗
PubMed1976

Pilocarpine therapy in glaucoma: effects on anterior chamber depth and lens thickness in patients receiving long-term therapy.

The effect of pilocarpine hydrochloride on the anterior chamber depth and lens thickness was measured in 20 eyes of patients with chronic open-angle glucoma who were receiving long-term glaucoma therapy with pilocarpine. Measurements were made with high-resolution ultrasonic biometry. This study demonstrated that regardless of their age (58.4 years, average) and the fact that they had been regularly using pilocarpine from two to four times a day, 85% of these patients demonstrated narrowing of the anterior chamber (AC) depth (average, 0.19 mm) and thickening of the lens (average, 0.21 mm) with each instillation of pilocarpine. In approximately 15% of eyes, a repeatable deepening of the AC depth and flattening of the lens was noted.

Administration, Topical↗
PubMed1993

High-frequency ultrasound quantitative analyses of corneal scarring following excimer laser keratectomy.

OBJECTIVE: To report objective grading and analysis of excimer laser-induced scarring using high-frequency ultrasound. METHODS: High-frequency ultrasound (50 MHz) corneal examination was performed on eight New Zealand white rabbits at different time points (10, 17, 24, and 74 days following phototherapeutic keratectomy). We used biometry and signal-processing techniques to determine corneal, epithelial, and scar thicknesses and to quantify the acoustic backscatter. RESULTS: Excimer laser-induced scarring showed an irregularly distributed acoustic hyperreflectivity that decreased through day 74. Corneal thickness remained reduced after ablation (mean, 318 microns compared with 419 microns for controls). Epithelial thickness averaged 62 microns and scar thickness, 87 microns. Scar peak and average anterior stroma acoustic backscatter ratios decreased from day 10 to day 74 (19.65 to 2.76, and 6.42 to 1.32, respectively). Histopathologic study showed increased keratocyte activity at early time points that correlated with acoustic backscatter ratios and imaging pattern. CONCLUSIONS: High-frequency ultrasound signal processing is a noninvasive method that quantitatively grades excimer laser-induced corneal scarring.

Animals↗
PubMed1994

Micrometer-scale resolution imaging of the anterior eye in vivo with optical coherence tomography.

OBJECTIVE: To demonstrate a new diagnostic technique, optical coherence tomography, for high-resolution cross-sectional imaging of structures in the anterior segment of the human eye in vivo. Optical coherence tomography is a new, noninvasive, noncontact optical imaging modality that has spatial resolution superior to that of conventional clinical ultrasonography (< 20 microns) and high sensitivity (dynamic range, > 90 dB). DESIGN: Survey of intraocular structure and dimension measurements. SETTING: Laboratory. PATIENTS: Convenience sample. MAIN OUTCOME MEASURES: Correlation with range of accepted normal intraocular structure profiles and dimensions. RESULTS: Direct in vivo measurements with micrometer-scale resolution were performed of corneal thickness and surface profile (including visualization of the corneal epithelium), anterior chamber depth and angle, and iris thickness and surface profile. Dense nuclear cataracts were successfully imaged through their full thickness in a cold cataract model in calf eyes in vitro. CONCLUSIONS: Optical coherence tomography has potential as a diagnostic tool for applications in noncontact biometry, anterior chamber angle assessment, identification and monitoring of intraocular masses and tumors, and elucidation of abnormalities of the cornea, iris, and crystalline lens.

Anterior Chamber↗
PubMed1996

Reduced trabecular meshwork height in juvenile primary open-angle glaucoma.

OBJECTIVE: To compare trabecular meshwork height in a series of patients with juvenile primary open-angle glaucoma (JPOAG) with that in normal control patients. METHODS: Ultrasound biomicroscopy and A-scan biometry were performed on 16 eyes with JPOAG and 24 normal eyes. A radial, perpendicular image in the horizontal temporal meridian detailing the line of Schwalbe, scleral spur, and angle anatomy was obtained for each eye by a single examiner. Trabecular meshwork height was defined as the distance from the scleral spur to the Schwalbe line. RESULTS: Mean patient age (P = .85, t test), refractive error (P = .68), sex distribution (P = .26, Fisher exact test) and axial length (P = .39) were similar between the groups. Mean +/- SE trabecular meshwork heights were 0.36 +/- 0.03 mm (range, 0.19-0.53 mm) for JPOAG and 0.58 +/- 0.02 mm (range, 0.40-0.80 mm) for controls (P < .001). Eyes with greater axial length tended to have larger trabecular meshworks in both groups (P = .012, multivariate regression). A trabecular meshwork height-axial length ratio of 0.021 or less was associated with a significantly increased risk for JPOAG being present (odds ratio, 57; 95% confidence interval, 6.0-541). CONCLUSIONS: The trabecular meshwork is smaller in eyes with JPOAG compared with that in normal eyes. This finding suggests a structural abnormality that may underlie the reduced outflow.

Adolescent↗
PubMed2000

Prenatal ages and stages-measures and errors.

BACKGROUND: The confusing term "gestational age" is generally either not defined or is used for menstrual "age," postovulatory age, or postfertilizational age. The designation (post)menstrual weeks and/or days is very useful in obstetrics but, because prenatal age extends from fertilization to birth, menstrual "age" is a misnomer. The term "stage" has a specific morphological meaning in embryology and should not be used either for ages or for lengths. METHODS: Embryonic age is best assessed, when possible, from the 23 internationally recognized morphological stages. A morphological staging system is not available for the fetal period, and fetal age is assessed mainly from measurements. RESULTS: Among these, the unsatisfactory designation crown-rump length (CRL) should be replaced, in ultrasonic biometry as well as in embryology, by the greatest length (GL), exclusive of the lower limbs. These points are discussed in detail, and justification for the views expressed is provided. CONCLUSIONS: The continuing confusion concerning prenatal age is shown to be unnecessary once the ambiguous and superfluous term "gestational age" is abandoned.

Crown-Rump Length↗
PubMed1999

Longitudinal observations in normally grown fetuses with tricuspid valve regurgitation: report of 22 cases.

Longitudinal observations of tricuspid valve regurgitation were prospectively performed in 22 singleton fetuses with normal anatomy, normal biometry and normal Doppler to determine the characteristics of functional tricuspid valve regurgitation. Tricuspid valve regurgitation was semi-quantified by spatial and temporal Doppler-derived parameters. In 18 cases tricuspid valve regurgitation was part-systolic (early and mid-systolic) and showed little spatial expansion of the jet as examined by colour Doppler flow imaging. In 16 of these 18 cases the maximum velocity of these regurgitant jets was below 2.00 m/s. Four fetuses demonstrated holosystolic regurgitant jets and in addition to the longer duration of these jets, the spatial expansion was also greater and the maximum velocity was slightly higher compared with the part-systolic tricuspid valve regurgitations. Re-examination of the 22 normally grown fetuses showed that tricuspid valve regurgitation was a transient phenomenon. Within a period of one to seven weeks after the diagnosis of tricuspid valve regurgitation, the regurgitation could no longer be demonstrated in any of these cases, including the four fetuses with holosystolic regurgitant jets. Tricuspid valve regurgitation was the only detected abnormality in all of these cases. The fetal outcome of the 22 normally grown fetuses with tricuspid valve regurgitation was unremarkable concerning the evaluated parameters. Although fetal tricuspid valve regurgitation may be a sign of increased preload, afterload or cardiac dysfunction, in most cases tricuspid valve regurgitation is an isolated transient phenomenon with little temporal and spatial expansion; nevertheless in some cases holosystolic tricuspid valve regurgitation may also be an isolated transient finding, and it may be a functional phenomenon.

Echocardiography, Doppler, Color↗
PubMed1999

Prenatal sonographic chest and lung measurements for predicting severe pulmonary hypoplasia.

UNLABELLED: Pulmonary hypoplasia was diagnosed sonographically in 32 fetuses from 20 to 33 weeks of gestation. In addition to standard biometry, transverse thoracic diameter (TTD), sagittal thoracic diameter (TSD), thoracic circumference (TC) and lung diameter (LD) were measured in all cases and compared with known nomograms. The fetuses were divided into five groups according to the main sonographic findings: group 1-skeletal dysplasia; group 2-renal agenesis; group 3-diaphragmatic hernia; group 4-hydrothorax; and group 5-others. Severe pulmonary hypoplasia (PH) was diagnosed prenatally in all cases on the basis of LD measurements. In 17 (53.1 per cent) out of 32 cases TTD was below the 5th percentile while lower TSD measurements were recorded in 15 (46.8 per cent) fetuses. A thorax circumference below the 5th percentile for the respective gestational age was found in 15 cases (46.8 per cent) and a decreased LD/TC ratio in 25 cases (78.1 per cent). In 13 out of 32 fetuses pulmonary hypoplasia was diagnosed before, and in 19 cases after 24 weeks of gestation. Pulmonary hypoplasia was confirmed by autopsy in all cases. CONCLUSION: pulmonary hypoplasia can be sonographically detected before 24 weeks of gestation. In cases of skeletal dysplasia and renal agenesis pulmonary hypoplasia can be diagnosed by chest and lung measurements, whereas in diaphragmatic hernia and hydrothorax diagnosis of pulmonary hypoplasia is possible only by lung measurement.

Bone Diseases, Developmental↗
PubMedDate not supplied

Folate status during labor: relationship with pregnancy outcome.

OBJECTIVE: The purpose of our study was to determine the folate status of pregnant women at labor, and to detect probable relationships with the gestational age at delivery, the birth weight of the newborns, as well as the mode of the delivery, taking into account any changes in the fetal heart rate (FHR) at labor and, subsequently, operative delivery. METHODS: Maternal serum folate levels were determined using automated fluorometric enzyme-linked assays. Gestational age was determined by ultrasound in the first trimester followed by serial fetal biometry. RESULTS: The results of our study in 101 consecutive pregnant women revealed that the mean (+/-SD) maternal serum concentration of the folate during labor was 12.01 (+/-4.16) ng/ml (range 2.50-23). The mean (+/-SD) gestational age at labor was 38.5 (+/-1.2) weeks (range 35-41 wks) as also the mean (+/-SD) birth weight of the newborns was 3.217 (+/-403) g (range 2,000-4,250 g). CONCLUSIONS: No significant correlation (p>0.05) between folate levels of the maternal serum and gestational age at delivery or birth weight was found. The mode of delivery as a result of probable relationship between operative delivery and maternal serum folate levels was also not found.

Adolescent↗