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At least 721 records · Page 40Linked to original sources

PubMed1998

Increased soft-tissue blood flow in patients with reflex sympathetic dystrophy of the lower extremity revealed by power Doppler sonography.

OBJECTIVE: We evaluated the ability of power Doppler sonography to show increased soft-tissue blood flow in patients with reflex sympathetic dystrophy of the lower extremity. SUBJECTS AND METHODS: Power Doppler sonography was performed in 30 patients with reflex sympathetic dystrophy of the lower extremity and in 26 asymptomatic control subjects. The bilateral power Doppler sonograms that were obtained of the soft tissues of the dorsum of the foot of each subject were grouped in pairs, and three sonologists who were unaware of clinical information independently reviewed the images. Images were evaluated for the amount of power Doppler signal shown on the following scale: 1 = no flow or minimal flow; 2 = mild flow; 3 = moderate flow; and 4 = marked flow. RESULTS: More power Doppler flow was seen in the patients with reflex sympathetic dystrophy than in the control subjects (p < .005). In addition, side-to-side asymmetry of flow was seen in patients, but this trend was not statistically significant (p < .20). Receiver operating characteristic (ROC) analysis showed that combined flow and asymmetry were more related to reflex sympathetic dystrophy than either parameter alone (area under the ROC curve: for flow, 0.748; for asymmetry, 0.566; for both, 0.799). We found that when the sum of power Doppler flow in both feet was greater than or equal to five, and asymmetry of flow was greater than or equal to one, the sensitivity of power Doppler sonography for reflex sympathetic dystrophy was 73% and the specificity was 92%. CONCLUSION: Patients with reflex sympathetic dystrophy of the lower extremity have increased power Doppler flow compared with asymptomatic control subjects. Patients may also exhibit more side-to-side asymmetry of flow than control subjects.

Adolescent↗

PubMed2003

Correlation of contrast-enhanced power Doppler sonography and conventional angiography of abduction-induced hip ischemia in piglets.

OBJECTIVE: The purpose of this study was to determine if enhanced power Doppler sonography can detect early ischemia of the capital femoral epiphysis induced by hip hyperabduction in piglets and to correlate these findings with angiography. MATERIALS AND METHODS: Proximal femoral perfusion was evaluated in 18 studies of 10 piglet hips with unenhanced power Doppler sonography, enhanced power Doppler sonography with IV contrast agent, and digital angiography, in neutral position, hyperabduction, and after release to neutral position. Enhancement ratios between pixel intensities of power Doppler sonography and enhanced power Doppler images in each position were calculated. Angiograms were analyzed for differences in flow with changes in hip position. RESULTS: With the piglet in neutral position, power Doppler sonography revealed few vessels in the femoral head. Contrast administration resulted in a temporary marked increase in the visualization of vessels in the femoral head. Quantitative enhanced power Doppler sonography revealed a marked decrease in pixel intensity with abduction (p < 0.001) that was not apparent on unenhanced studies (p = 0.28). The enhancement ratio decreased from 0.45 (mean +/- SD, +/- 0.26) in neutral position to 0.10 (+/- 0.21) after abduction; it returned to 0.41 (+/- 0.14) after release of abduction (p < 0.001 for each comparison). Angiographic studies in hyperabduction revealed a variable level of ischemia. CONCLUSION: Enhanced power Doppler sonography can be used to visualize the vascular supply to the cartilaginous femoral head in piglets and can detect reversible ischemia induced by hip hyperabduction. These differences correlate with digital angiographic evidence of ischemia.

Angiography↗

PubMed2004

How many pigs? Statistical power considerations in swine nutrition experiments.

Replication refers to the assignment of more than one experimental unit to the same treatment. Each replication of a treatment is an independent observation; thus, each replication involves a different experimental unit. In swine nutrition research, the experimental unit may be an individual animal, as in sow reproduction experiments, or a group of animals, as in growing-finishing pig experiments. In either case, calculation of the number of replicates needed to give an accurate and reliable outcome is an important step in deriving an experimental protocol. Although investigators often seem to choose replication arbitrarily on the basis of cost or availability of animals, housing considerations, convenience, or tradition, the question of how many pigs (i.e., how much replication is necessary) is a statistical one that has a statistical answer. A power analysis, performed while designing an experiment, will provide an investigator with an estimate of the number of replicates needed for an experiment of known power and sensitivity. This a priori, or prospective, power analysis ensures that an investigator does not waste time and resources carrying out an experiment that has little chance of finding a significant effect, if one exists. It also makes sure resources are not wasted by including more experimental units than are necessary to detect an effect. A retrospective, or a posteriori, power analysis may also be conducted. If no significant effects are found in an experiment, an investigator can assess the observed power of the experiment, or may determine the size of treatment effect that could have been detected using the standard deviation and number of replicates in the experiment. The latter may be useful in explaining results. However, the former may be misleading because a high P-value will invariably result in a low observed power, and little new information will be gained from the post hoc power analysis. In most cases, the time for making power calculations is before, not after, an experiment is conducted.

Animal Nutritional Physiological Phenomena↗

PubMed1992

The brain in fractal time: 1/f-like power spectrum scaling of the human electroencephalogram.

"1/f-like" power spectrum scaling is a ubiquitous feature of complex systems. In such scaling, the power spectrum of a given time series is dominated by an inverse power law, resulting in an inverse linear relation between log power and log frequency. The 1/f-like power spectrum scaling properties of human, resting eyes-closed and eyes-open EEG were examined. For both eyes-closed and eyes-open EEG, log power had a significant inverse linear relation with log frequency. The slope of this relation was not correlated with previously-calculated Grassberger-Procaccia dimension estimates for the same data, indicating that the EEG is not a 1/f-like stochastic process. Further, the degree of deviation from perfect log power versus log frequency linearity was related to power in the 8-12 Hz alpha frequency band. It is speculated that this deviation may be related to the low dimension of a chaotic alpha rhythm relative to other EEG rhythms.

Adult↗

PubMed1998

Powered prosthetic hands in very young children.

Myoelectric prostheses are generally not provided in the United Kingdom for children before the age of 3 1/2 years. Following the introduction of a smaller sized electric hand in the United Kingdom in 1993 the authors decided to introduce electrically powered hands for a group of congenital upper limb deficient children at a much younger age compared to normal practice. Eleven children were introduced to powered prosthetic hands at an average age of 20.6 months. At the review carried out for the purpose of this paper. 72.7% of these children appeared to be successfully using these powered prostheses. Fitting these young children with powered prostheses and encouraging acceptance and operation of the prostheses appeared to be much less of a problem than might have been anticipated. The parents of all these children have very much liked the introduction of powered hands at this early age and have contributed positively to the prosthetic programme. The authors' experience suggests that introduction of a powered prosthesis at a much earlier age can be a more suitable alternative than provision of a body-powered prosthetic device while waiting to reach an older age before a powered prosthesis is considered.

Arm↗

PubMed1995

Biological effects of power-frequency fields as they relate to carcinogenesis.

There is a widespread public perception that exposure to electricity is linked to cancer. The public concern stems largely from epidemiological studies which appear to show a relationship between cancer incidence and exposure to power-frequency electromagnetic fields. This review will discuss the biophysics of power-frequency electromagnetic fields as it relates to biological effects, summarize the current state of the cancer epidemiology, and then concentrate on the laboratory studies that are relevant to addressing the possibility that power-frequency fields are carcinogenic. Review of the epidemiological evidence shows that the association between exposure to power-frequency fields and cancer is weak and inconsistent, and generally fails to show a dose-response relationship. The laboratory studies of power-frequency fields show little evidence of the type of effects on cells or animals that point towards power-frequency fields causing or contributing to cancer. Finally, from what is known about the biophysics of power-frequency fields, there is no reason to even suspect that they would cause or contribute to cancer. Application of "Hill's criteria" to epidemiological and laboratory studies shows that the evidence for a causal association between exposure to power-frequency fields and the incidence of cancer is weak.

Animals↗

PubMed2006

Effects of rate of decrease in power output in decrement-load exercise on oxygen uptake.

The purpose of this study was to examine how oxygen uptake (Vo2) in decrement-load exercise (DLE) is affected by changing rate of decrease in power output. DLE was performed at three different rates of decrease in power output (10, 20 and 30 watts.min(-1): DLE10, DLE20 and DLE30, respectively) from power output corresponding to 90 % of peak Vo2. Vo2 exponentially increased and then decreased, and the rate of its decrease was reduced at low power output. The values of Vo2 in the three DLE tests were not different for the first 2 min despite the difference in power output. The relationship between Vo2 and power output below 50 watts was obtained as a slope to estimate excessive Vo2 (ex-Vo2) above 50 watts. The slopes were 10.0+/-0.9 for DLE10, 9.9+/-0.7 for DLE20 and 10.2+/-1.0 ml.min(-1).watt(-1) for DLE30. The difference between Vo2 estimated from the slope and measured Vo2 was defined as ex-Vo2. The peak value of ex-Vo2 for DLE10 (189+/-116 ml.min(-1)) was significantly greater than those for DLE20 and for DLE30 (93+/-97 and 88+/-34 ml.min(-1)). The difference between Vo2 in DLE and that in incremental-load exercise (ILE) below 50 watts (DeltaVo2) was greater in DLE30 and smallest in DLE10. There were significant differences in DeltaVo2 among the three DLE tests. The values of DeltaVo2 at 30 watts were 283+/-152 for DLE10, 413+/-136 for DLE20 and 483+/-187 ml.min(-1) for DLE30. Thus, a faster rate of decrease in power output resulted in no change of Vo2 at the onset of DLE, smaller ex-Vo2 and greater DeltaVo2. These results suggest that Vo2 is disposed in parallel in each motor unit released from power output or recruited in DLE.

Adult↗

PubMedDate not supplied

Intraocular lens power calculation for eyes after refractive keratotomy.

BACKGROUND: Calculating the intraocular lens (IOL) power for an eye that has previously had refractive keratotomy is a problem because of the difficulty of accurately measuring the central power of the cornea using standard keratometers. METHODS: Three methods are proposed to better estimate this parameter. The clinical history method involves subtracting the change in myopia induced by the refractive keratotomy from the average corneal power measured before the keratotomy. The contact lens method determines the difference between the manifest refraction with and without a plano hard contact lens of known base curve and subtracts this difference from that base curve. Videokeratography measures the central corneal power inside the approximately 3-mm zone measured by keratometry, and therefore gives a more accurate power to use in IOL calculation formulas, especially with newer software applications becoming available. RESULTS: Published reports have demonstrated that standard keratometers do not accurately measure corneal power after refractive keratotomy and that regression formulas are less accurate than modern third-generation theoretic formulas for eyes that have flatter corneas from refractive surgery. CONCLUSION: For eyes that have had refractive surgery, the corneal power derived from clinical history, contact lens refraction, or videokeratography should be used in a third-generation theoretic formula (Hoffer Q, Holladay, SRK/T) to calculate the intraocular lens power used during cataract surgery.

Contact Lenses↗

PubMed1999

A perspective on standardizing the predictive power of noninvasive cardiovascular tests by likelihood ratio computation: 1. Mathematical principles.

The current practice of reporting positive and negative predictive value (PV), sensitivity (Se), and specificity (Sp) as measures of the power of noninvasive cardiovascular tests has significant limitations. A test result's PV and its comparison with other test results are highly dependent on the pretest disease prevalence at which it is determined; the citation of sensitivity and specificity provides no succinct or explicit quantitation of the rule-in and rule-out power of a test. This article presents a rationale for the use of an alternative standard for expressing predictive power in the form of positive and negative likelihood ratios, (+)LR and (-)LR. The likelihood ratios are composite expressions of test power, which incorporate the Se and Sp and their respective complements [(1 - Se) and (1 - Sp)], thus yielding single unambiguous measures of positive and negative predictive power. The likelihood ratios are calculated as follows: (+)LR = Se/(1 - Sp) and (-)LR = Sp/(1 - Se). On analysis of the predictive value equations, the likelihood ratios equal the quotients of the posttest predictive value odds to the pretest prevalence odds for disease and no disease, respectively, as follows: (+)LR = (+)PVOd/POD and (-)LR = (-)PVOn/PON, where (+)PVOd is positive predictive value odds for disease, POD is prevalence odds for disease, (-)PVOn is negative predictive value odds for no disease, and PON is prevalence odds for no disease. Thus, the likelihood ratios are measures of the odds advantage in posttest probability of disease or no disease relative to pretest probability, independent of disease prevalence in the tested population. The quotients of the (+)LR or the (-)LR among test results studied in a common population are direct expressions of their relative predictive power in that population. The likelihood ratio principle is applicable to the evaluation of the predictive power of multiple tests performed in a common population and to estimating predictive power at multiple test thresholds.

Confidence Intervals↗

PubMed1998

Comparison of power Doppler and B-scan sonography for renal imaging using a sonographic contrast agent.

The goal of this study was to evaluate the relative performance of power Doppler and B-scan imaging modes in detecting vascular perfusion changes resulting from injection of a contrast agent. To allow this comparison the imaging plane and the contrast agent injection must be the same for both modes. We achieved this by using a rigid transducer holder and simultaneously recording power Doppler and B-scan images on separate videotapes. The kidneys of five adult beagles were scanned to allow a comparison of how power Doppler and B-scan imaging methods monitor changes during the injection of 0.1 ml/kg of a contrast agent, EchoGen emulsion (Sonus Pharmaceuticals, Bothell, WA). The changes in the images were assessed qualitatively by three radiologists and quantitatively using a custom-designed image analysis software. All of the radiologists agreed that no visually detectable changes occurred in B-scan images but that significant changes could be observed in power Doppler images. Image analysis also indicated a difference between power Doppler and B-scan images. The change in mean color level of power Doppler images could be displayed as an indicator dilution curve with a peak enhancement of 46 +/- 16 above the preinjection value. The time at which mean color level peaked was 18 +/- 13 s. The mean color level returned to half of the peak value by 69 +/- 42 s and returned to the preinjection baseline value by 148 +/- 73 s. Conversely, B-scan images showed statistically insignificant changes, and time measurements could not be made. By all measures used to evaluate images, power Doppler imaging had a greater sensitivity in detecting changes resulting from contrast agent injection than B-scan imaging. This finding indicates that power Doppler imaging of contrast agent injections can be used to map regional differences in flow as well as quantitative measurements of a contrast agent's transit time and has the potential to assess kidney abnormalities associated with renal blood flow.

Animals↗

PubMed2003

Three-dimensional power Doppler imaging in depicting vascularity in hepatocellular carcinoma.

OBJECTIVE: To assess the ability of three-dimensional power Doppler imaging to depict vascularity in hepatocellular carcinoma. METHODS: Forty-three patients with hepatocellular carcinomas were subjected to two- and three-dimensional power Doppler imaging, and 14 of them also underwent angiography. The delineated amounts of intratumoral Doppler signals were compared between 2 methods of power Doppler imaging in 43 patients. In the 14 patients who also underwent angiography, the patterns of blood supply depicted by 2 methods of power Doppler imaging were compared with that depicted by angiography, and the intratumoral vascularity on three-dimensional projection images and angiograms was also quantitatively assessed by calculating the vascularity-area ratio with graphics software. RESULTS: In comparison with two-dimensional power Doppler imaging, three-dimensional power Doppler imaging was subjectively determined as showing more intratumoral Doppler signals in 32 (74.4%) of the 43 lesions. The accuracies in depicting vascular patterns were 64.3% (9 of 14) for three-dimensional projection images and 14.3% (2 of 14) for two-dimensional slices compared with the results of angiography. The vascularity-area ratios on three-dimensional power Doppler imaging projections and angiograms were 46.0% +/- 25.6% and 48.5% +/- 22.5% (mean +/- SD), respectively (P > .05). Three-dimensional projection images correlated significantly with angiograms in quantifying the vascularity (gamma = 0.87; P < .001). CONCLUSIONS: A three-dimensional power Doppler projection image gives a better overall picture of vascular distribution than a two-dimensional slice and correlates with angiography significantly for delineating vascularity in hepatocellular carcinoma.

Adult↗

PubMed2003

Radiosensitivity of rat mammary tumors correlates with early vessel changes assessed by power Doppler sonography.

OBJECTIVE: To investigate the changes occurring in the vascularization of tumors during irradiation, we used a model of autochthonous mammary tumors in rats and assessed early vascular changes after irradiation by power Doppler sonography. METHODS: Mammary tumors were induced in 24 female Sprague Dawley rats by a single subcutaneous injection of N-nitroso N-methyl urea. After tumor areas reached 1 cm2, the animals received a single fraction of 18-Gy radiation or intraperitoneal saline injection. Power Doppler sonographic quantification of detected vessels was performed 1 day before irradiation and 7 days after the use of a power Doppler index of 5 different tumor imaging planes. Final tumor shrinkage was compared with early changes in the power Doppler index. Not all tumors regressed in a similar fashion. Radiosensitive tumors were defined as tumors with a greater than 50% decrease in baseline area 28 days after irradiation, whereas radioresistant tumors were tumors with a less than 50% decrease in baseline area. Statistical analysis was performed by the Mann-Whitney U test. RESULTS: Tumor area changes were similar in radioresistant and radiosensitive tumors 7 days after irradiation (-41% and -35%, respectively; P > .05, not significant), whereas reduction in the power Doppler index was significantly greater in radiosensitive tumors (mean value, -63%) than in radioresistant tumors (mean value, -12%) (P = .001). Late tumor regrowth was correlated with day 7 power Doppler index changes (P = .009). A 40% reduction in the power Doppler index at day 7 distinguished 8 of 9 radiosensitive tumors and 8 of 9 radioresistant tumors (P = .003). CONCLUSIONS: This study suggests that early changes in tumor perfusion as assessed by power Doppler sonography after tumor irradiation may precede the long-term tumor regression.

Animals↗

PubMed1999

Slow EEG-power spectra correlate with haemodynamic changes during laryngoscopy and intubation following induction with fentanyl or sufentanil.

We studied nociception-associated arousal following laryngoscopy and intubation in patients scheduled for elective open heart surgery, using EEG power spectra and hemodynamics. Either fentanyl (7 micrograms/kg; n = 30) or sufentanil (1 microgram/kg; n = 30) were given in a randomized fashion to induce anesthesia in heavily premedicated patients, followed by pancuronium bromide (100 micrograms/kg). EEG-power spectra (delta, theta, alpha, beta) as well as mean arterial blood pressure (MAP) and heart rate (HF) were measured at the following end-points: before the induction of anesthesia (control), 1 and 10 minutes after laryngoscopy and intubation (L & I). Linear regression analysis was computed to determine which of the EEG power spectra was most sensitive to detect insufficient blockade of nociceptive-related arousal when correlated with haemodynamics. In the fentanyl group the change in HF closely correlated with the decrease of power in the slow delta- and theta-domain (r2 = 0.98 and r2 = 0.89 respectively) of the EEG. The change in MAP also closely correlated with a decrease in the slow delta- and theta-domain (r2 = 0.97 and r2 = 0.99 respectively). There was little correlation in regard to spectral edge frequency (SEF) and HF and MAP changes (r2 = 0.36 and r2 = 0.12 respectively). In the sufentanil group the change in HF correlated closely with an increase of power in the fast alpha and a decrease in the slow theta-domain (r2 = 0.91 and r2 = 0.98 respectively) of the EEG. The changes in MAP closely correlated with an increase in the fast alpha-band a decrease in the slow theta-domain (r2 = 0.98 and r2 = 0.73 respectively). Also there was little correlation of SEF with HF and MAP changes (r2 = 0.09 and r2 = 0.02 respectively). Among the EEG-spectra, reduction of power in the slow delta- and theta-bands are the most sensitive parameters to determine insufficient antinociception of opioids commonly used for the induction in cardiac anesthesia. Increase of power in the alpha-band seems to be closely correlated with cortical reactivation and reduction of hypnosis, while a reduction of power especially in the deltabut more so in the theta-band of the EEG reflects nociception related arousal.

Alpha Rhythm↗

PubMedDate not supplied

Adequacy of power wheelchair control interfaces for persons with severe disabilities: a clinical survey.

The extreme difficulty with which persons with severe disabilities have been taught to maneuver a power wheelchair has been described in case studies, and anecdotal evidence suggests the existence of a patient population for whom mobility is severely limited if not impossible given currently available power wheelchair control interfaces. Since our review of the literature provided little evidence either in support or refutation of the adequacy of existing power wheelchair control interfaces, we surveyed 200 practicing clinicians, asking them to provide information about their patients and to give their impressions of the potential usefulness of a new power wheelchair navigation technology. Significant survey results were: Clinicians indicated that 9 to 10 percent of patients who receive power wheelchair training find it extremely difficult or impossible to use the wheelchair for activities of daily living. When asked specifically about steering and maneuvering tasks, the percentage of patients reported to find these difficult or impossible jumped to 40. Eighty-five percent of responding clinicians reported seeing some number of patients each year who cannot use a power wheelchair because they lack the requisite motor skills, strength, or visual acuity. Of these clinicians, 32 percent (27 percent of all respondents) reported seeing at least as many patients who cannot use a power wheelchair as who can. Nearly half of patients unable to control a power wheelchair by conventional methods would benefit from an automated navigation system, according to the clinicians who treat them. We believe these results indicate a need, not for more innovation in steering interfaces, but for entirely new technologies for supervised autonomous navigation.

Activities of Daily Living↗

PubMedDate not supplied

SLO power calibration.

We present a method for calibrating the Scanning Laser Ophthalmoscope (SLO) that predicts radiant power at any of 256 grayscale values (gsv) and 12 polarized filter (polarizer) levels. Predicted power values, p(gsv), were determined by substitution into polynomials linearly transformed to old or new power at p(0) and p(255). This was compared with observed power values at 125 levels of attenuation/session. Prediction accuracy was the proportion of nonsignificant pairwise comparisons (t-test, p=0.0001). We found that power transformation between polarizers and within sessions has both linear and nonlinear characteristics. Within polarizer and between sessions, however, power transformation has linear characteristics. A 5th-degree polynomial was individually fit, at each polarizer, to session 1 power distributions of 9 gsv steps (0, 31, 63, 95, 127, 159, 191, 223, 255). When adjusted to p(255) and p(0) in new sessions, we obtained p(gsv) that predicted power at 25 gsv * 5 polarizers for 18 days with an accuracy of about 0.84. When only adjusted to p(255), predictive accuracy was 0.81.

Calibration↗

PubMed2001

Development of a field test for upper-body power.

The purpose of this study was to develop a field test capable of measuring upper-body power through the use of a common weight-training apparatus, a Smith machine (SM), set up for bench press (BP) movement. A small, battery-operated digital timing device was designed and constructed to allow a precise calculation of power (in conjunction with measures of distance and force) for this specific movement, which involved an explosive press from the chest to a position just short of full arm extension. In pilot work, 1 repetition maximums (1RM) were determined on the SM BP for 3 male subjects, and by subsequently testing power on the same subjects at varying resistances, an average relative percentage of the 1RM-producing peak power values was found by power curve analysis for test standardization. Reliability was assessed (using 11 men) by SM power measurements taken over 3 days on the SM fitted with the timer. An intraclass R (0.998) indicated a high correlation between the 3 separate field-test trials. Finally, 8 male subjects were used to compare SM scores with a criterion measure, the Linea Isokinetic BP station (Loredan Biomedical, Inc., Sacramento CA). A Pearson product moment coefficient found a high correlation between the field test (SM) and Linea power scores (r = 0.987). A 2-tailed dependent t-test between the field and criterion scores was not significant, suggesting that no consistent error variable was present. It can be concluded that this is a valid field test of power for this movement.

Adult↗

PubMed2002

Body composition estimations by BIA versus anthropometric equations in body builders and other power athletes.

BACKGROUND: Two main questions are stated: 1) are BIA and anthropometric equations accurate in estimating body composition in male power athletes and more specifically in body builders and 2) is there a difference in body composition when body builders are compared to weight and power lifters? METHODS EXPERIMENTAL DESIGN: this is a descriptive, comparative study on a selected sample of power athletes. PARTICIPANTS: 49 Belgian elite and sub-top male power athletes (34 body builders and 15 weight and power lifters) were included in this sample. More than 70% was in preparation of competition at time of data collection. MEASURES: an extended set of anthropometric measures was taken. Body composition was estimated by BIA (Bioelectrical Impedance Analysis) and by regression equations of skinfolds. Somatotype and muscle+bone areas were calculated. Factor analysis on all anthropometric measures was carried out to determine the body structure of the athletes. RESULTS: Compared to external visual criteria, the equations of Durnin and Womersley and Lohman (skinfolds) and the Guo-equation (BIA) were the only equations that could accurately estimate the body composition for this specific group of athletes. However, the sum of skinfolds attains the most accurate estimate of subcutaneous fatness. Body builders have significantly (p<0.01) larger arm and thigh circumferences and are more mesomorfic than the other power athletes (5.9 vs 3.8). CONCLUSIONS: This study shows that to estimate body composition in extreme power athletes BIA is not as accurate as compared to anthropometric equations. Moreover, the sum of a larger set of skinfolds is preferred to anthropometric prediction equations. In addition, body builders are more muscular and leaner than other power athletes.

Adipose Tissue↗

PubMed2002

[Research on the forecast of intraocular lens power after excimer laser keratorefractive operation].

OBJECTIVE: To study the accuracy of different formulas forecasting intracellular lens (IOL) power after excimer laser keratorefractive operation. METHODS: One hundred and twenty eyes (60 cases) underwent LASIK surgery. Before and after the surgery, the IOL powers were calculated to correct the myopia to emmetropia by experiential SRK II formula, theoretical SRK/T formula and Binkhoist II formula respectively. Then we calculated the IOL power equal to original lens power by F, and analyzed the results before and after surgery by SPSS statistical software. RESULTS: 1. The IOL powers were not obviously different by different formulas between pre-operative and post-operative results in low myopia (P > 0.05). In middle and high myopia there were obvious differences (P < 0.01), the postoperative results were smaller than the preoperative ones. 2. The differences of equal IOL power by different formulas were highly related to the practical corrective refractive values of the surgery. Regression formula: The difference of equal IOL power = a + b x the practical corrective refractive value of the surgery. (SRK II: a = -l.23, b = 0.72; SRK/T: a = -l.03, b = 0.52; Binkhoist II: a = -1.44, b = 0.5). CONCLUSION: The IOL powers forecasted by different formulas are smaller in middle and high myopia after excimer laser keratorefractive operation than that before the operation, and can be corrected by regression formula.

Adolescent↗