SEARCH · PubMed Health

Results for “Biometry”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 559 records · Page 31Linked to original sources

PubMed2003

Comparison of biometric measurements using partial coherence interferometry and applanation ultrasound.

PURPOSE: To compare and contrast axial length (AL) measurements assessed by ultrasound biometry and optical biometry. SETTING: Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany. METHODS: Optical biometry and ultrasound biometry were performed in 360 eyes to measure AL. RESULTS: In eyes with a clear-appearing crystalline lens, there was a statistically significant median difference in AL measurements between the 2 methods in eyes with a normal or long length. In eyes with cataract, there was a statistically significant median difference in AL measurements in eyes with a normal or short length. In these cases, optical biometry produced larger readings than ultrasound biometry. In eyes with a posterior chamber intraocular lens, there was no statistically significant difference between the 2 methods in eyes of all lengths. In all eyes, the 2 methods produced reliable measurements. CONCLUSIONS: These results show that optical biometry and ultrasound applanation biometry give statistically significant differences in AL measurement in patients with cataract and normal lenses. In these cases, optical biometry provided clinically relevant larger values than ultrasound applanation. Optical biometry provides an alternative to ultrasound biometry. However, ultrasound biometry may be indicated in certain complex cases.

Biometry↗

PubMed2001

Improved prediction of intraocular lens power using partial coherence interferometry.

PURPOSE: To evaluate the feasibility of using a new optical biometry technique, dual-beam partial coherence interferometry (PCI), to improve intraocular lens (IOL) power prediction in cataract surgery. SETTING: Department of Ophthalmology, Vienna General Hospital, and Institute of Medical Physics, University of Vienna, Vienna, Austria. METHODS: Preoperative axial length (AL) data obtained with PCI biometry and applanation ultrasound (US) biometry in 77 eyes of 51 patients was applied to 4 commonly used IOL power formulas. The refractive outcome and the mean absolute error (MAE) were calculated for each formula using both biometry methods. A linear multiple-regression model based on preoperative PCI biometry data was derived to predict the postoperative anterior chamber depth (ACD). The predictive power of this regression model was assessed by adding the predicted ACD to the SRK/T formula. Predicted residuals were calculated to evaluate the feasibility and stability of this modified IOL power formula. RESULTS: Using PCI instead of US biometry significantly improved the refractive outcome with all 4 IOL power formulas. The Holladay I and SRK/T formulas yielded an MAE of 0.44 diopter (D) using PCI AL data and 0.56 D and 0.57 D, respectively, using US biometry data. The SRK/T formula combined with the PCI regression model for postoperative ACD prediction performed slightly better (MAE 0.42 D) than the conventional SRK/T formula alone. Predicted residuals revealed an MAE of 0.46 D, proving the predictive performance of the new formula. CONCLUSIONS: Partial coherence interferometry biometry applied to several widely used IOL power formulas yielded significantly better IOL power prediction and therefore refractive outcome in cataract surgery than US biometry. Further improvement can be achieved by applying PCI to a modified SRK/T formula that predicts the postoperative ACD using PCI biometry data.

Biometry↗

PubMed1989

Clinical indications for intraocular lens power calculation: a prospective randomised study.

Patients about to undergo cataract extraction were assessed clinically using several criteria to try and judge the necessity for biometry. The patients judged not to need biometry were allocated randomly to two groups, one of which had biometry. The only significant clinical criterion for biometry was found to be the wearing of glasses since before the age of 30 years. Several unexpectedly high refractive errors occurred in the group of patients who did not have biometry. In the group of patients judged not to need biometry but allocated to the biometry group, refractive results were significantly better (nearer to target refractions) than in the unmeasured group. Routine pre-operative biometry is probably the only way to avoid unexpected high ametropia, and it also improves the refractive results. There is however much room for improvement in the accuracy of biometry.

Age Factors↗

PubMed2001

Accuracy of intraocular lens power calculations using the Zeiss IOL master. A prospective study.

PURPOSE: Partial Coherence Interferometry (PCI) is a fast, noncontact method to calculate lens implant power for cataract surgery. It has been reported as a potentially more accurate method than ultrasound biometry. Prospective study of the refractive outcomes of a consecutive series of patients undergoing phacoemulsification surgery with preoperative biometry by both ultrasound A-scan and PCI. METHODS: A series of 50 eyes of 35 patients underwent small-incision phacoemulsification cataract surgery and lens implantation by one single surgeon. All patients had preoperative biometry performed by both ultrasound using the Sonomed and IOL Master optical biometry. The IOL Master results were included in the SRK II formula to calculate the lens implant power. Postoperative refractive assessment was performed 4 weeks after surgery. RESULTS: The mean difference in axial length between ultrasound and optical biometry was 0.2 mm. The IOL Master measures a longer axial length. The mean keratometric power using the Javal instrument was 43.4 D and for the Zeiss IOL Master it was 42.9 D. At the week 4 postsurgery assessment, the overall refractive outcome was in the range of +/- 1D. Five patients were unable to undergo PCI biometry due to the density of cataract. CONCLUSIONS: Intraocular lens power calculations using the Zeiss IOL Master are easy to perform and result in excellent refractive outcomes. A-scan biometry is still needed in case of mature cataract.

Biometry↗

PubMed2005

Secondary intraocular lens implantation of traumatic cataract in open-globe injury.

BACKGROUND: The purpose of this study was to determine the visual outcome and accuracy of biometry in traumatic cataract in open-globe injury. METHODS: A clinical retrospective study of 30 consecutive patients treated for ocular penetrating trauma was conducted. Patient demographics, causes of injury, wound categories, timing and procedures of the primary repair, interval of subsequent intraocular lens (IOL) implantation, follow-up, and postoperative complications were recorded. Additionally, binocular biometry was documented. Twenty-six eyes (86.7%) were open-globe injuries occurring in the workplace. All patients received cataract extraction with primary repair of the penetrating wound, 18 eyes (60%) underwent trans pars plana vitrectomy with lensectomy and 12 eyes (40%) underwent lens aspiration or extracapsular cataract extraction. Simultaneously, 16 eyes (53.3%) underwent intraocular foreign body removal. RESULTS: The mean visual improvement after secondary IOL implantation was statistically significant (p = 0.002). Seventeen eyes (56.7%) achieved final best-corrected visual acuity of 20/40 or better. The mean deviation of final refraction and target refraction was -0.69 +/- 0.56 diopter, and 23 eyes (76.7%) were within 1 diopter based on biometry of the traumatic eye. In 18 eyes (60%), the difference was within 1 diopter according to biometry of the fellow eye. In 5 cases (16.7%), there was no improvement of vision because of central corneal scar, secondary glaucoma, macular pucker, or recurrent retinal detachment. INTERPRETATION: The vision of patients with traumatic cataract in open-globe injury was improved after prompt surgical intervention and subsequent IOL implantation. A minority of patients experienced no change in vision or a deterioration of vision due to irregular astigmatism caused by a corneal wound or variable damage to the posterior segment. Using biometry of the injured eye after primary repair was more accurate than using biometry of the fellow eye to determine the power of the lens for IOL implantation in variable open-globe injury.

Adolescent↗

PubMed2005

Relationship between cerebroplacental Doppler ratio and birth weight in postdates pregnancies.

OBJECTIVES: To explore the relationship between cerebroplacental Doppler impedance index and birth weight in postdates pregnancies, and to evaluate the use of a combination of Doppler parameters and ultrasound biometry in the prediction of large-for-gestational age (LGA) fetuses at 41 weeks of gestation. METHODS: The pulsatility indices of the umbilical (UA-PI) and middle cerebral (MCA-PI) arteries, the cerebroplacental pulsatility index ratio (CPR) and the estimated fetal weight (EFW) were obtained in a cohort of 181 ultrasound-dated pregnancies at 41 weeks' gestation, 2 days before induction of delivery. A regression equation was established and the correlation between umbilical artery impedance and different birth-weight centile groups was determined. A receiver-operating characteristics (ROC) curve was used to compare prediction of LGA fetuses using biometry alone with that using biometry and UA-PI. RESULTS: UA-PI was inversely related to EFW (Spearson's correlation coefficient rho = -0.28, P < 0.001). Logistic regression showed an independent contribution of UA-PI to the birth-weight estimation (birth weight = 1356.8 - 232.0 x UA-PI + 0.65 x EFW). On ROC curve analysis, the prediction of LGA with the regression equation was comparable to that using ultrasound biometry alone. CONCLUSION: UA-PI was inversely correlated to EFW, but the combination of ultrasound biometry and UA-PI compared with biometry alone showed similar prediction of LGA fetuses in postdates pregnancies. Further prospective trials on larger populations or groups with a higher prevalence of LGA fetuses would be needed to validate the use of the new formula.

Adult↗

PubMed1993

Intraobserver reliability of amniotic fluid volume estimation by two techniques: amniotic fluid index vs. maximum vertical pocket.

We evaluated the intraobserver agreement of two techniques of amniotic fluid assessment: amniotic fluid index and maximum vertical pocket. The intraobserver variation of the two forms of amniotic fluid assessment was obtained by evaluating amniotic fluid prior to fetal biometry (post-biometry value) and after fetal biometry (pre-biometry value). Between January and June 1990, this amniotic fluid assessment was by the maximum vertical pocket technique, and between July and December 1990, by the amniotic fluid index technique. In the Grace Maternity Hospital, Vancouver, 352 subjects were evaluated by the maximum vertical pocket technique, and 184 subjects by the amniotic fluid index technique.Amniotic fluid volumes were categorized into normal, oligohydramnios, and polyhydramnios, and the pre-biometry and post-biometry categories of amniotic fluid index and maximum vertical pocket techniques were compared by kappa statistics. The maximum vertical pocket technique showed poor intraobserver agreement (kappa = 0.33), but the amniotic fluid index technique showed good agreement (kappa = 0.72). With the poor reproducibility of the maximum vertical pocket technique in assessing extremes of amniotic fluid volume, it is difficult to support its use as a component of fetal assessment.

Journal Article↗

PubMed2005

Paired observations of refractive error after cataract surgery.

PURPOSE: To quantify the design effect if pairing between eyes is ignored when reporting refractive outcome following cataract surgery. METHODS: A retrospective review was conducted of biometry prediction error in 612 patients who had bilateral phacoemulsification with intraocular lens (IOL) implantation. The levels of uncertainty (confidence interval and variance) of the estimates for the biometry prediction error were compared when intra-cluster correlation between ocular measurements of paired eyes within each patient was either taken into account or ignored. The design effect (the ratio of the two variances) was calculated. RESULTS: The correlation between the two eyes was weak, as indicated by the intra-cluster correlation coefficient of 0.22 (confidence limits 0.15-0.30). The mean biometry prediction error was 0.73 dioptres (D) and the 95% confidence limits for the mean in the two situations were similar at 0.69-0.76D and 0.69-0.77D, respectively. The variance of the biometry prediction error if pairing of eyes was ignored (0.00033D) was slightly less than if pairing was taken into account (0.00041D). This yielded a design effect of 1.2. CONCLUSIONS: A high correlation between data collected from pairs of eyes is not inevitable. If data on both eyes are used to estimate biometry prediction error, the usual statistical procedures will underestimate the standard errors and the variance, but the effect will be trivial and the confidence intervals only negligibly smaller. The maximum variance is expected to be 1.2 times higher than that given by simple statistical methods that ignore the pairing of eyes.

Biometry↗

PubMed2006

Comparison of postoperative refractive outcome in phacotrabeculectomy and phacoemulsification with posterior chamber intraocular lens implantation.

PURPOSE: To compare the postoperative refractive outcomes following phacotrabeculectomy and phacoemulsification with posterior chamber intraocular lens implantation. METHODS: A retrospective comparative study of 90 consecutive patients (95 eyes) with cataract with or without co-existing glaucoma who had undergone uncomplicated phacotrabeculectomy or phacoemulsification by a single surgeon. The biometry prediction error was determined for each case by the difference between the actual postoperative refraction and the preoperative predicted refractive outcome, in spherical equivalent. This was followed by a comparative analysis of the mean biometry prediction error, and the number of cases with error >0.50 D or 1.00 D. All biometry measurements were performed by one of the two qualified optometrists. RESULTS: The mean and absolute mean biometry prediction error of the 25 eyes that received phacotrabeculectomy (+0.20 D, absolute error 0.96 D) was comparable to the 70 eyes that received phacoemulsification (-0.14 D, absolute error 0.68 D), P = 0.18 (absolute error, P = 0.12). The proportion of cases with prediction error >0.50 D or 1.00 D was 60% or 40% for phacotrabeculectomy, and 44% or 17% for phacoemulsification, respectively. Phacotrabeculectomy was more likely to have a prediction error >1.00 D (P = 0.02) and a myopic shift of >0.50 D or 1.00 D (P = 0.03 or 0.02, respectively). No significant differences were found with regard to the frequency of hyperopic shift or prediction error >0.50 D. There was no significant difference in either the mean error or the frequency of the different types of error for the different biometry operators, types of glaucoma, or postoperative intraocular pressure control success status. CONCLUSION: Myopically shifted prediction error was significantly more frequent following posterior chamber intraocular lens implantation with phacotrabeculectomy compared with phacoemulsification, even when surgery was uncomplicated and performed by the same surgeon.

Aged↗

PubMed1998

Subtle ultrasonographic anomalies: do they improve the Down syndrome detection rate?

OBJECTIVE: Our purpose was to determine whether the identification of subtle anomalies further improves Down syndrome detection over standard ultrasonographic biometry and the detection of gross morphologic defects. STUDY DESIGN: The screening efficiency of clinodactyly, dilated renal pelvis (> or =4 mm), echogenic bowel, mild ventriculomegaly (> or =10 to 15 mm), and two-vessel cord was determined prospectively in midtrimester fetuses at amniocentesis. The screening efficiency of increased nuchal thickness and shortened long-bone length (standard biometry) and gross morphologic defects was determined for comparison. Multiple backward stepwise regression analysis was used to determine which subtle anomalies significantly correlated with Down syndrome detection rate and whether they increased Down syndrome detection over that with standard biometry and morphologic defects. RESULTS: Although all subtle anomalies except two-vessel cord correlated with the presence of Down syndrome on univariate analysis, only echogenic bowel (Wald chi2 = 15.0211, p = 0.0001) and clinodactyly (Wald chi2 = 9.4273, p = 0.002) persisted in regression analysis of the subtle anomaly group. When either of the above-described anomalies was present, the detection rate for Down syndrome was 28.6%, p < 0.00001. For the combination of standard biometry (either increased nuchal thickness or short humerus) or gross anatomic defect, Down syndrome detection rate was 53.3% (p < 0.00000001). This increased to 63.2% (p < 0.00000001) when subtle anatomic defects (either echogenic bowel or clinodactyly) were included in the definition of an abnormal sonogram. CONCLUSION: Subtle anomalies, of which echogenic bowel and clinodactyly are the most significant, further increase Down syndrome screening efficiency over standard biometry or the finding of gross anatomic defect. Our data appear to support the addition of subtle anomaly findings to ultrasonographic screening for Down syndrome.

Abnormalities, Multiple↗

PubMed1996

Risk of Down syndrome and any clinically significant chromosome defect in pregnancies with abnormal triple-screen and normal targeted ultrasonographic results.

OBJECTIVE: Our purpose was to study prospectively the use of ultrasonographic biometry to refine the risk estimates for both Down syndrome and any clinically significant chromosome defect in women with abnormal biochemical triple-screen results. STUDY DESIGN: Ultrasonographic biometry and anatomic survey were performed on study and control cases. Expected values for humerus, femur, combined humerus plus femur lengths, and abdominal circumference were generated on the basis of biparietal diameter obtained from a normal group. Threshold observed/expected values of each measurement for screening for Down syndrome and clinically significant chromosome defects were determined with receiver-operator characteristic curves. By stepwise logistic regression analysis the optimal screening parameters, including nuchal thickness, for detection of Down syndrome and clinically significant chromosome defect were determined. Risk tables for chromosome anomalies were developed on the basis of ultrasonography and triple-screen values. RESULTS: Of 1034 cases at risk for Down syndrome (risk > or = 1/270) or trisomy 18 on the basis of triple-screen results, there were 11 cases of Down syndrome, 1 of trisomy 18, and 17 clinically significant chromosome defects. Abnormal nuchal thickness or observed/expected humerus length < 0.92 was the most sensitive parameter for Down syndrome detection. Abnormal nuchal thickness or observed/expected combined femur and humerus length < 0.90 was the most sensitive for significant chromosome defects. With abnormal biometry or anatomy the Down syndrome risk was 8 of 127 versus 1 of 753 in normals, odds ratio 50.4 (95% confidence interval 6.4 to 90.2), p < 0.00001, and the risk of significant defects was 11 of 90 versus 6 of 830 in normals, odds ratio 19.3 (95% confidence interval 6.4 to 60.5), p < 0.00001. In a pregnancy with a 1 in 270 triple-screen risk for Down syndrome, normal biometric and anatomic results reduce the risk to 1 in 2100. CONCLUSION: Normal ultrasonographic anatomy and biometry significantly reduces the risk of both Down syndrome and any significant chromosome defects in pregnancies with abnormal triple-screen results.

Biochemistry↗

PubMed2001

The repeatability and accuracy of axial length and anterior chamber depth measurements from the IOLMaster .

BACKGROUND: Axial length and anterior chamber depth have been measured clinically using conventional ultrasound biometry. Recently, a non-contact device has become available to measure these parameters. This study evaluated the repeatability and accuracy of this device. METHODS: The axial length and anterior chamber depth were measured by two practitioners on a group of young subjects using the IOLMaster followed by a conventional ultrasound biometer operated by a third practitioner. The accommodation was controlled in ultrasound biometry through a full correction on the non-measured eye and a distant fixation target. RESULTS: There was good repeatability and accuracy of axial length assessment. The mean difference between the IOLMaster and ultrasound biometry was -0.099 mm, with 95% limits of agreement between 0.66 and -0.85 mm. The axial length was slightly shorter from the IOLMaster and the difference was not significant. The anterior chamber depth was repeatable but was shown to be deeper than the ultrasound results. The mean difference in anterior chamber depth between the IOLMaster and ultrasound biometry was 0.15 mm, with 95% limits of agreement between 0.34 and -0.03 mm. It is suggested that the former device is not measuring the axial anterior chamber depth. CONCLUSIONS: The IOLMaster is a non-contact 'optical' A-scan which is simple to use and good for axial length assessment. The anterior chamber depth assessment should be further evaluated.

Adult↗

PubMed2005

Accuracy of intraoperative retinoscopy in corneal power and axial length estimation using a high plus soft contact lens.

AIM: To assess the accuracy of intraoperative retinoscopy with high plus soft contact lens (CL) in estimating corneal power and the axial length compared with standard keratometry and biometry measurement. METHODS: Intraoperative retinoscopy was performed in 30 eyes prior to the implantation of an intraocular lens (IOL). A +10 D disposable soft contact lens was applied on the cornea to minimize retinoscopic error. Corneal power was derived from refraction using biometric axial length while the axial length was derived using keratometric measurement. Refraction derived corneal powers and axial lengths from 26 eyes within +/-1.00 D of the target postoperative refraction were compared with preoperative standard keratometry and biometry measurements. RESULTS: In the 26 eyes, the mean difference between the corneal powers derived from refraction and keratometry was 0.35 D (S.D.=1.678). The 95% limits of agreement were -3.006 to +3.706. The mean difference between the axial lengths derived from refraction and biometry was 0.15 mm (S.D.=0.721). The 95% limits of agreement were -1.292 to 1.542. CONCLUSION: Intraoperative retinoscopy with a high plus soft contact lens after phacoemulsification is useful but not accurate in estimating corneal power or axial length of the eye. It should be used cautiously in IOL power calculation as a substitute for standard keratometry or biometry machines when either of these is not available or in error.

Aged↗

PubMed1997

[Intraoperative skiascopy for determining the refractive value of an implantable intraocular lens].

BACKGROUND: Preoperative biometry for calculation of the refractive power of intraocular lenses is not sufficiently reliable in certain cases. Most frequently inaccuracies tend to occur in highly myopic eyes. Preceding refractive procedures can also impair IOL-calculation or even make it impossible. PATIENTS: In a highly myopic patient IOL-power calculation was not possible with conventional calculation formulas due to a preexisting refractive silicone lens located between the cataractuous natural lens and the iris. In another myopic patient ultrasound measurement of axial eye length produced variable and unreliable results. Therefore retinoscopy was performed intraoperatively in the aphakic eye. Refractive power of the IOL was calculated using a new formula. For validation of the method retinoscopy was performed intraoperatively in a second group of 11 patients with unproblematic ultrasound biometry. RESULTS: In 3 eyes IOL power was chosen according to intraoperative retinoscopy. A maximal deviation of 1.25 D from the aimed refraction resulted. In the second group, the retinoscopic method produced partially considerably inaccurate results as compared to the ultrasound biometry. Inaccuracies increased with the extent of hyperopia. CONCLUSIONS: In cases of difficult or inaccurate preoperative ultrasound biometry IOL power can be estimated after intraoperative retinoscopy in the aphacic highly myopic eye. IOL power can be calculated instantly using computer programs or tables. This method additionally enables the surgeon to control the refractive result of intraocular lens implantation prior to wound closure. However this method lacks reliability in higher hyperopic eyes, as in these cases small changes in corneal vertex distance of the lens used for retinoscopy highly alter the result.

Adult↗

PubMed2001

[Value of a new non-contact biometer for intraocular crystalline lens power calculation].

PURPOSE: One of cataract surgery's current imperatives involves refraction: the power of the lens implant must be calculated as accurately as possible. Here we present a new method of biometric ocular measurement using the partial optical consistency interferometer. MATERIAL AND METHODS: This investigation studied the axial length measurement of 100 eyes. Five measurements were taken with a classic echobiometric contact technique using the ultrasonic mode; 5 others were taken with the infrared noncontact technique (IOL Master, Zeiss Humphrey). The latter technique is based on interferometric biometry with optical consistency and measurements were taken with an infrared luminous ray. With extreme rapidity and no contact, the device provides a complete biometry, including axial length, keratometry, and anterior chamber depth. It includes a built-in computer. RESULTS: Comparing the ultrasonic and infrared measurements emphasizes the precision and particularly the high reproducibility of the infrared method. The standard deviations of the samples were significantly lower for the 100 measurements. Its limitations depends on the type of cataract since success was not obtained for certain posterior subcapsular opacities. DISCUSSION: This new method of performing a biometry with a partial consistency interferometer contributes a number of advantages: speed, its noninvasive nature with no contact, the high reproducibility of the exam, as well as precise measurements as shown by the difference in the standard deviations of the two methods. CONCLUSION: Biometry using the optical consistency interferometer seems to be a reliable, reproducible, and precise technique that brings great precision for the calculation of the power of the intraocular implant in cataract surgery.

Diagnostic Techniques, Ophthalmological↗

PubMed1994

The sonographic assessment of twin growth discordancy.

OBJECTIVE: To determine: 1) the frequency with which standard fetal biometry (head circumference [HC], abdominal circumference [AC], and femur length [FL]) and the transverse cerebellar diameter can be measured in twin pregnancies; and 2) the efficacy of fetal biometry using these measures in the detection of twin growth discordancy. METHODS: The study population consisted of 203 twin pregnancies reviewed retrospectively. The frequency with which standard biometry and the transverse cerebellar diameter could be obtained was recorded. Forty-nine twin pairs who were delivered within 3 weeks of their last ultrasound examination were divided into three groups based on birth weight differences: 20% or more, 10-19%, and less than 10%. The sensitivity, specificity, and predictive values of the specific fetal biometric measurements and of the sonographic estimation of fetal weight were assessed for this subgroup for the prediction of twin discordancy. RESULTS: The FL could be measured consistently throughout gestation, but the ability to measure the AC decreased after 35 weeks' gestation. The frequency with which HC and transverse cerebellar diameter could be measured decreased with advancing gestation. The transverse cerebellar diameter could be measured only in 91 of 151 and 14 of 49 pregnancies at 31-35 and 36-40 weeks' gestation, respectively. An intra-pair AC difference of 20 mm or more had a sensitivity and a positive predictive value of 83% for the detection of twin discordancy, defined as at least a 20% difference in birth weight. Estimated fetal weight had a sensitivity and positive predictive value of 92.9 and 72%, respectively. In contrast, a difference of 4 mm or more in the intra-pair transverse cerebellar diameter had a sensitivity of 28% and a positive predictive value of 50% in detecting twin weight discordancy. CONCLUSIONS: Appropriate twin fetal biometry can be measured throughout gestation. Estimated fetal weight has a higher sensitivity but a lower positive predictive value than AC for predicting twin growth discordancy.

Anthropometry↗

PubMed2006

The influence of the biometric parameters on metallothionein and metal level in the heat-treated cytosol of the whole soft tissue of transplanted mussels.

The influence of the biometric parameters (shell mass, whole soft tissue mass, condition index) on MT and metal levels in the heat-treated cytosol of the whole soft tissue of transplanted mussels was studied over the period of one year. The positive correlation of three metals (Cd, Fe, Zn) with the shell mass indicated to time-dependent increase of their contents. Strong correlation of Mn content with the whole soft tissue mass (r = 0.74, p < 0.0001), and almost identical changes of these two parameters over the year make Mn a good indicator of mussel's condition. As opposed to the other metals, Cu content does not exhibit connection with biometry. On the other hand, MTs are highly influenced by biometry. As much as 65% of their variability could be explained by the changes of the shell mass and the whole soft tissue mass. Consequently, it is difficult to distinguish if the obtained positive correlation between Cd and MTs (r = 0.48, p < 0.05) reflects MT induction by Cd, or Cd accumulation as a result of age-dependent increase of MTs. Due to the strong influence of the biometry on MT level, the whole soft tissue is not considered as the best choice for measuring MTs as a biomarker. Better option would be to isolate a specific tissue that shows indisputable connection between MT induction and metal accumulation.

Animals↗

PubMed2002

Effect of pupil dilation on the accuracy of the IOLMaster.

PURPOSE: To evaluate the effect of pupil dilation on the accuracy of the IOLMaster (Zeiss) in performing biometry and to assess test-retest variability without pupil dilation. SETTING: Ophthalmic outpatient department of a district general hospital. METHODS: This prospective study comprised consecutive patients presenting to a cataract clinic (study group) who had biometry performed with the IOLMaster before and after pupil dilation. A control group was recruited from consecutive patients attending a cataract preassessment clinic who had 2 sets of biometric measurements with the IOLMaster but without pupil dilation. The SRK/T formula was used to calculate intraocular lens (IOL) power. RESULTS: The IOLMaster showed excellent reproducibility in the control group with no significant test-retest variability between the 2 sets of readings. The study group showed a statistically significant change in K2 and average keratometry values (P <.05) but no significant change in axial length or IOL power between undilated and dilated pupil biometry readings. No systematic errors were revealed. CONCLUSIONS: Dilating the pupil did not adversely affect the clinical accuracy of the IOLMaster.

Animals↗