Standard Mean Deviation Research Articles

Zinc and Copper Levels in Bladder Cancer: A Systematic Review and Meta-Analysis

It is well documented that oxidative stress is involved in the pathogenesis of bladder cancer. Zinc (Zn) and copper (Cu) are important components of antioxidants. However, the association between Zn or Cu levels and bladder cancer remains elusive. The present study was designed to investigate the alteration of serum and urinary levels of Zn or Cu in bladder cancer patients compared with controls by performing a systematic review. We searched the PubMed, Embase, and Cochrane databases from January 1990 to March 2013 to identify studies that met our predefined criteria. Six studies were included. Bladder cancer patients demonstrated significantly lower levels of serum Zn (three studies, random effects standard mean deviation (SMD): -1.072, 95% CI: -1.489 to -0.656, P <0.0001), markedly higher levels of serum Cu (three studies, random effects SMD: 1.069, 95% CI: 0.302 to 1.836, P = 0.006) and urinary Zn (three studies, random effects SMD: 2.114, 95% CI: 0.328 to 3.899, P = 0.02) compared with controls. No obvious difference was observed in urinary Cu levels between bladder cancer patients and controls (two studies, random effects SMD: 0.153, 95% CI: -0.244 to 0.55, P = 0.449). No evidence of publication bias was observed. In conclusion, the disorder of Zn and Cu is closely associated with bladder cancer. Frequent monitoring and early intervention should be recommended.

Acoustic system for the estimation of the temporary blood chamber volume of the POLVAD heart supporting prosthesis

BackgroundThe paper presents a newly researched acoustic system for blood volume measurements for the developed family of Polish ventricular assist devices. The pneumatic heart-supporting devices are still the preferred solution in some cases, and monitoring of their operation, especially the temporary blood volume, is yet to be solved.MethodsThe prototype of the POLVAD-EXT prosthesis developed by the Foundation of Cardiac Surgery Development, Zabrze, Poland, is equipped with the newly researched acoustic blood volume measurement system based on the principle of Helmholtz’s acoustic resonance. The results of static volume measurements acquired using the acoustic sensor were verified by measuring the volume of the liquid filling the prosthesis. Dynamic measurements were conducted on the hybrid model of the human cardiovascular system at the Foundation, with the Transonic T410 (11PLX transducer - 5% uncertainty) ultrasound flow rate sensor, used as the reference.ResultsThe statistical analysis of a series of static tests have proved that the sensor solution provides blood volume measurement results with uncertainties (understood as a standard mean deviation) of less than 10%. Dynamic tests show a high correlation between the results of the acoustic system and those obtained by flow rate measurements using an ultrasound transit time type sensor.ConclusionsThe results show that noninvasive, online temporary blood volume measurements in the POLVAD-EXT prosthesis, making use of the newly developed acoustic system, provides accurate static and dynamic measurements results. Conducted research provides the preliminary view on the possibility of reducing the additional sensor chamber volume in future.

Variability of indication criteria in knee and hip replacement: an observational study

BackgroundTotal knee (TKR) and hip (THR) replacement (arthroplasty) are effective surgical procedures that relieve pain, improve patients' quality of life and increase functional capacity. Studies on variations in medical practice usually place the indications for performing these procedures to be highly variable, because surgeons appear to follow different criteria when recommending surgery in patients with different severity levels. We therefore proposed a study to evaluate inter-hospital variability in arthroplasty indication.MethodsThe pre-surgical condition of 1603 patients included was compared by their personal characteristics, clinical situation and self-perceived health status. Patients were asked to complete two health-related quality of life questionnaires: the generic SF-12 (Short Form) and the specific WOMAC (Western Ontario and Mcmaster Universities) scale. The type of patient undergoing primary arthroplasty was similar in the 15 different hospitals evaluated.The variability in baseline WOMAC score between hospitals in THR and TKR indication was described by range, mean and standard deviation (SD), mean and standard deviation weighted by the number of procedures at each hospital, high/low ratio or extremal quotient (EQ5-95), variation coefficient (CV5-95) and weighted variation coefficient (WCV5-95) for 5-95 percentile range. The variability in subjective and objective signs was evaluated using median, range and WCV5-95. The appropriateness of the procedures performed was calculated using a specific threshold proposed by Quintana et al for assessing pain and functional capacity.ResultsThe variability expressed as WCV5-95 was very low, between 0.05 and 0.11 for all three dimensions on WOMAC scale for both types of procedure in all participating hospitals. The variability in the physical and mental SF-12 components was very low for both types of procedure (0.08 and 0.07 for hip and 0.03 and 0.07 for knee surgery patients). However, a moderate-high variability was detected in subjective-objective signs. Among all the surgeries performed, approximately a quarter of them could be considered to be inappropriate.ConclusionsA greater inter-hospital variability was observed for objective than for subjective signs for both procedures, suggesting that the differences in clinical criteria followed by surgeons when indicating arthroplasty are the main responsible factors for the variation in surgery rates.

Two-phase TOPSIS of uncertain multi-attribute group decision-making

To solve the uncertain multi-attribute group decisionmaking of unknown attribute weights, three optimal models are built to decide the corresponding ideal solution weights, standard deviation weights and mean deviation weights. The comprehensive attribute weights are gotten through the product of the above three kinds of weights. And each decision maker's weighted decision matrices are also received by using the integrated attribute weights. The closeness degrees are also gotten by use of technique for order preference by similarity to ideal solution (TOPSIS) through dealing with the weighted decision matrices. At the same time the group decision matrix and weighted group decision matrix are gotten by using each decision-maker's closeness degree to every project. Then the vertical TOPSIS method is used to calculate the closeness degree of each project. So these projects can be ranked according to their values of the closeness degree. The process of the method is also given step by step. Finally, a numerical example demonstrates the feasibility and effectiveness of the approach.

Effect of Cataract Extraction on the Glaucoma Progression Index (GPI) in Glaucoma Patients

To determine the effect of cataract extraction on the glaucoma progression index (GPI) in glaucoma patients with coexisting cataract. This is a retrospective noncomparative study. Consecutive eligible patients with glaucoma who underwent phacoemulsification alone or in combination with augmented trabeculectomy were included. All patients had Swedish Interactive Threshold Algorithm-standard 24-2 visual fields within 10 months of surgery. Exclusion criteria included other ocular morbidity, intraoperative complications, and perimetric reliability indices greater than 33%. Comparison was made between the immediate visual fields before and after surgery. The main outcome measure was the change in GPI. Changes in the pattern standard deviation (PSD) and mean deviation (MD) were also assessed. Comparison of means was performed with the paired t test. Thirty-three eyes of 33 patients (all Whites) were analyzed. The mean age at surgery was 77.0+/-8.7 years. Visual field tests were performed 3.3+/-3.0 months SD before surgery and 5.4+/-2.6 months after surgery. There was a statistically significant increase in the GPI after cataract surgery (from 71.5+/-18.5% to 74.6+/-17.1%; P=0.02). The improvement in MD was also statistically significant (from -11.8+/-5.3 to -10.2+/-5.3 dB; P <0.01), but the change in PSD did not reach statistical significance. Uncomplicated cataract extraction resulted in a statistically significant improvement in the 24-2 Swedish Interactive Threshold Algorithm-standard GPI and MD, but not in PSD. Both the MD and the GPI may be influenced by lens opacities, which could make detection of glaucoma visual field progression more difficult for clinicians in glaucoma patients with concurrent cataract.

Standard and mean deviation methods for linguistic group decision making and their applications

This paper proposes two methods for multi-attribute decision making problems with linguistic information, in which the preference values take the form of linguistic variables. Based on the ideal that the attribute with a larger deviation value among alternatives should be assigned a large weight, two methods named standard deviation method and mean deviation method are proposed to determine the optimal weighting vector objectively under the assumption that attribute weights are completely unknown. Two numerical examples are examined using the proposed methods to show the advantages from the other methods. It is shown that the proposed methods are straightforward and no loss of information.

Vision-specific Quality of Life in Greek Glaucoma Patients

The aim of the study was to assess the vision-specific quality-of-life (VS-QoL) of Greek glaucoma patients, and the impact of potential influencing factors. This was a 2-center, cross-sectional study. One hundred twenty-one patients were recruited from the outpatient glaucoma service and 100 successfully responded to the self-administered, Greek version of the National Eye Institute Visual Function Questionnaire 25. The results were quantified in terms of scores (0-100) and correlations with possible modifiers were investigated. The effects of sex, income, education, and comorbidities on VS-QoL scores were examined by analysis of variance. Our sample consisted of 49 men and 51 women with a mean age of 64.1 years, ranging from 18 to 89 years. The QoL score (mean+/-SD) was 81.7+/-14.7, the mean general health subscale score was 57.3+/-21.0 and the mean general vision subscale score was 72.7+/-16.3. Men generally presented higher VS-QoL scores (P=0.042). Age had a negative impact on the "General health" (rho=-0.325, P=0.001) and "General vision" (rho=-0.265, P=0.008) subscales. Higher educational background contributed to higher scores in General health, "General vision," and "Central vision" while urban residence correlated with "Distant activities" and "Social functioning". Cup-to-disc ratio, visual acuity and visual field indices like the Advanced Glaucoma Intervention Study, the Hodapp-Anderson-Parrish, and the Collaborative Initial Glaucoma Treatment Study scores, and pattern standard deviation and mean deviation all correlated with National Eye Institute Visual Function Questionnaire scores (r values ranging from -0.240 to 0.757). In this first study in a Greek native population, both the structural measure of cup-to-disc ratio and a multitude of functional scores correlated with VS-QoL scores in glaucoma patients.

Diagnostic Accuracy of Pattern Electroretinogram Optimized for Glaucoma Detection

To assess the ability of the new pattern electroretinogram optimized for glaucoma detection (PERGLA) paradigm to discriminate between healthy individuals and individuals with glaucomatous optic neuropathy (GON). Cross-sectional study. One hundred forty-two eyes of 71 participants (42 healthy and 29 with GON in at least 1 eye) enrolled in the University of California, San Diego, Diagnostic Innovations in Glaucoma Study were studied. Healthy individuals were those recruited as healthy with healthy-appearing optic disc by examination and masked stereoscopic optic disc photograph evaluation. Glaucomatous optic neuropathy was defined based on stereophotograph evaluation. The PERGLA (Glaid Elettronica, Pisa, Italy) recordings were obtained within 6 months of standard automated perimetry (SAP) testing. Dependent variables were PERGLA amplitude, phase, amplitude asymmetry, phase asymmetry, and SAP pattern standard deviation (PSD) and mean deviation (MD). Diagnostic accuracy (sensitivity and specificity) of the PERGLA normative database for classifying healthy and glaucomatous individuals was determined. In addition, performance (areas under receiver operating characteristic curves [AUCs]) of PERGLA amplitude and phase for classifying healthy (n=84) and GON (n=50) eyes was determined. Results from both analyses were compared with those from SAP. Sensitivity and specificity of the PERGLA normative database were 0.76 and 0.59, respectively, compared with 0.83 and 0.77 for SAP. The AUCs for PERGLA amplitude and phase were 0.75 and 0.50 (chance performance), respectively. The AUCs for SAP PSD and MD were 0.83 and 0.78, respectively. Pattern electroretinograms recorded using the PERGLA paradigm can discriminate between healthy and glaucoma eyes, although this technique performed no better than SAP at this task. Low specificity of the PERGLA normative database suggests that the distribution of recordings included in the database is not ideal.

The Correlation Between Visual Field Defects and Focal Nerve Fiber Layer Thickness Measured With Optical Coherence Tomography in the Evaluation of Glaucoma

To study the correlation between known visual field defects and retinal nerve fiber layer (RNFL) thickness detected by optical coherence tomography (OCT) in glaucomatous eyes. Visual field parameters and OCT RNFL measurements of 28 eyes of 28 glaucoma patients with various stages of glaucoma were compared with 38 eyes of 38 normal age-matched controls. A perimetric nerve fiber bundle map was built by dividing the visual field area into 21 zones. Mean deviation and pattern standard deviation values within these 21 zones were compared with OCT RNFL thickness measurements in 12 sectors and the results were analyzed. Average RNFL thickness was 62.90+/-16.56 microm in the glaucoma group and 111.90+/-6.00 microm in the control group (P<0.05). Pattern standard deviation and mean deviation visual field zones and corresponding OCT RNFL thickness sectors were significantly correlated at specific sectors in the glaucoma group (P<0.01). Analysis of RNFL thickness in eyes with focal glaucomatous visual field defects showed good structural and functional correlation with OCT. OCT contributes to the identification of focal defects in the RNFL of glaucoma patients.

Interindividual variability of electromyographic patterns and pedal force profiles in trained cyclists

The aim of this study was to determine whether high inter-individual variability of the electromyographic (EMG) patterns during pedaling is accompanied by variability in the pedal force application patterns. Eleven male experienced cyclists were tested at two submaximal power outputs (150 and 250 W). Pedal force components (effective and total forces) and index of mechanical effectiveness were measured continuously using instrumented pedals and were synchronized with surface electromyography signals measured in ten lower limb muscles. The intersubject variability of EMG and mechanical patterns was assessed using standard deviation, mean deviation, variance ratio and coefficient of cross-correlation (_R(0), with lag time = 0). The results demonstrated a high intersubject variability of EMG patterns at both exercise intensities for biarticular muscles as a whole (and especially for Gastrocnemius lateralis and Rectus femoris) and for one monoarticular muscle (Tibialis anterior). However, this heterogeneity of EMG patterns is not accompanied by a so high intersubject variability in pedal force application patterns. A very low variability in the three mechanical profiles (effective force, total force and index of mechanical effectiveness) was obtained in the propulsive downstroke phase, although a greater variability in these mechanical patterns was found during upstroke and around the top dead center, and at 250 W when compared to 150 W. Overall, these results provide additional evidence for redundancy in the neuromuscular system.

Short-term variation of autorefraction in Diabetic Macular Edema (DME) *

Very few studies have investigated autorefraction in diabetic subjects presenting either with diabetic retinopathy (DR) and/ or diabetic macular edema (DME). To the best of our knowledge this is the first study using multivariate methods for investigating short-term autorefraction in a small sample of subjects diagnosedwith DME. Forty consecutive autorefractor measurements were taken over a short interval on each of seven diabetic subjects with varying stages of DME, and the results were compared to a smaller group of four diabetic control subjects without DME (reasons for the differences in sample sizes will be explained later). Measurements were obtained from both the right and left eyes of all subjects. Subjects in the two groups were similarly matched according to duration of diabetes mellitus (DM), age and glycated hemoglobin (HbA1c) values. Normality of data distribution was mostly achieved with the removal of outliers (where necessary) until profiles of skewness, kurtosis, and standard mean deviation exhibited near-normal distribution. Thereafter, stereo-pair scatter plots with 95% surfaces of constant probability density (distribution ellipsoids) were generated and compared between the experimental and control subjects.The diabetic subjects with DME demonstrated a larger spread of measurements in the eyes with the more severe DME, with the exception of one subject (subject 5). The volumes and orientation of the distribution ellipsoids also differed between the subject’s eyes. Some eyes with severe DME and poor visual acuitydisplayed more stigmatic variation (for example, subjects 2 and 4), while others (subjects 1 and 3) displayed more ortho-antistigmatic variation or near oblique antistigmatic variation (subject 7). In all experimental subjects, with the exception of subject 5, the eye with the more severe DME had a larger distribution ellipsoidvolume, indicating greater variation in autorefraction and thus it might be surmised that this paper provides some preliminary data to suggest that diabetic subjects with DME display greater short-term variation of refractive behaviour when compared to diabetic subjects without DME. Secondly, in diabetic subjects withDME, eyes with the more severe DME or worse VA also display greater variation of refractive status. However, there seemed to be no distinctive or obvious pattern to the type of variation.In addition, a suitable statistic in terms of a Cubic Root Difference (CRD) was introduced in this study to compare inter-ocular ellipsoidal volumes. This statistic is also useful for comparing variances between eyes, or between means for groups of eyes, and could be used in studies involving anisometropia, et cetera. Nevertheless, this study suggests that further investigation remains necessary before autorefraction can be used effectively in the early diagnosis, monitoring, and assessment of eyes with diabetic-related complications to the macular regions.

Relationship between Retinal Nerve Fiber Layer and Visual Field Sensitivity as Measured by Optical Coherence Tomography in Chiasmal Compression

To investigate the spatial relationship between retinal nerve fiber layer (RNFL) thickness measured with optical coherence tomography (OCT) and visual field sensitivity (VFS) measured by standard automated perimetry (SAP) in chiasmal compression. Twenty-six patients with chiasmal compression were enrolled. RNFL thickness was measured with the StratusOCT and VFS with SAP (Humphrey Field Analyzer; both from Carl Zeiss Meditec, Dublin, CA). Relationships between RNFL thickness (in clock hours, hemifields, and sectors) and VFS (zones were divided into hemifields, quadrants, and sectors based on a validated visual field map) expressed in a decibel scale and 1/lambert (L) were evaluated by linear and nonlinear regression. Coefficients of determination (R(2)) were calculated by using a multivariate model. Average RNFL thickness correlated strongly with pattern standard deviation (PSD; R = 0.622) and mean deviation (MD; R = 0.413). The four strongest correlations were between the 8 o'clock OCT position (temporal disc), with the temporal hemifield (R = -0.813), the superotemporal quadrant (R = -0.847), the inferotemporal quadrant (R = -0.855), and the field sector representing the papillomacular bundle (R = -0.809). Coefficients of determination improved significantly in all sectors when time since surgery was included in the regression model-most notably, average thickness and 1/L (R(2) = 0.35-0.49), the decibels (R(2) = 0.31-0.47), and the temporal sector (R(2) = 0.44-0.57). This is the first study to compare the structure-function correlation of RNFL measured by OCT with SAP in patients with chiasmal compression. RNFL is topographically related globally and sectorally to decreased SAP, with the temporal sectors showing the strongest correlations. The correlation between RNFL and VFS strengthens as the time from surgical intervention increases.

Detecting Early Functional Damage in Glaucoma Suspect and Ocular Hypertensive Patients With the Multifocal VEP Technique

To determine whether the multifocal visual evoked potential (mfVEP) technique can detect early functional damage in ocular hypertensive (OHT) and glaucoma suspect (GS) patients with normal standard achromatic automated perimetry (SAP) results. Twenty-five GS patients (25 eyes), 25 patients with OHT (25 eyes), and 50 normal controls (50 eyes) were enrolled in this study. All GS, OHT and normal control eyes had normal SAP as defined by a pattern standard deviation and mean deviation within the 95% confidence interval and a glaucoma hemifield test within normal limits on the Humphrey visual field 24-2 program. Eyes with GS had optic disc changes consistent with glaucoma with or without raised intraocular pressure (IOP), and eyes with OHT showed no evidence of glaucomatous optic neuropathy and IOPs >or=22 mm Hg. Monocular mfVEPs were obtained from both eyes of each subject using a pattern-reversal dartboard array with 60 sectors. The entire display had a radius of 22.3 degrees. The mfVEPs, for each eye, were defined as abnormal when either the monocular or interocular probability plot had a cluster of 3 or more contiguous points with P<0.05 and at least 2 of these points with P<0.01. The mfVEP results were abnormal in 4% of the eyes from normal subjects. Abnormal mfVEPs were detected in 20% of the eyes of GS patients and 16% of the eyes of OHT patients. Significantly more mfVEP abnormalities were detected in GS patients than in normal controls. However, there was no significant difference in mfVEP results between OHT patients and normal controls. The mfVEP technique can detect visual field deficits in a minority of eyes with glaucomatous optic disks and normal SAP results.

Structure and Function of the Voltage Sensor of Sodium Channels Probed by a β-Scorpion Toxin

Voltage sensing by voltage-gated sodium channels determines the electrical excitability of cells, but the molecular mechanism is unknown. beta-Scorpion toxins bind specifically to neurotoxin receptor site 4 and induce a negative shift in the voltage dependence of activation through a voltage sensor-trapping mechanism. Kinetic analysis showed that beta-scorpion toxin binds to the resting state, and subsequently the bound toxin traps the voltage sensor in the activated state in a voltage-dependent but concentration-independent manner. The rate of voltage sensor trapping can be fit by a two-step model, in which the first step is voltage-dependent and correlates with the outward gating movement of the IIS4 segment, whereas the second step is voltage-independent and results in shifted voltage dependence of activation of the channel. Mutations of Glu(779) in extracellular loop IIS1-S2 and both Glu(837) and Leu(840) in extracellular loop IIS3-S4 reduce the binding affinity of beta-scorpion toxin. Mutations of positively charged and hydrophobic amino acid residues in the IIS4 segment do not affect beta-scorpion toxin binding but alter voltage dependence of activation and enhance beta-scorpion toxin action. Structural modeling with the Rosetta algorithm yielded a three-dimensional model of the toxin-receptor complex with the IIS4 voltage sensor at the extracellular surface. Our results provide mechanistic and structural insight into the voltage sensor-trapping mode of scorpion toxin action, define the position of the voltage sensor in the resting state of the sodium channel, and favor voltage-sensing models in which the S4 segment spans the membrane in both resting and activated states.

Industrial application of ultrasound based in-line rheometry: From stationary to pulsating pipe flow of chocolate suspension in precrystallization process

In-line visualization and on-line characterization of nontransparent fluids becomes an important subject for process development in food and nonfood industries. In our work, a noninvasive Doppler ultrasound-based technique is introduced. Such a technique is applied for investigation of nonstationary flow in the chocolate precrystallization process. Unstable flow conditions were induced by abrupt flow interruption and were followed up by strong flow pulsations in the piping system. While relying on available process information, such as absolute pressures and temperatures, no analyses of flow conditions or characterization of suspension properties could possibly be done. It is obvious that chocolate flow properties are sensitive to flow boundary conditions. Therefore, it becomes essential to perform reliable structure state monitoring and particularly in application to nonstationary flow processes. Such flow instabilities in chocolate processing can often lead to failed product quality with interruption of the mainstream production. As will be discussed, a combination of flow velocity profiles, on-line fit into flow profiles, and pressure difference measurement are sufficient for reliable analyses of fluid properties and flow boundary conditions as well as monitoring of the flow state. Analyses of the flow state and flow properties of chocolate suspension are based on on-line measurement of one-dimensional velocity profiles across the flow channel and their on-line characterization with the power-law model. Conclusions about flow boundary conditions were drawn from a calculated velocity standard mean deviation, the parameters of power-law fit into velocity profiles, and volumetric flow rate information.

Effect of cataract extraction and intraocular lens implantation on nerve fibre layer thickness measurements by scanning laser polarimeter (GDx) in glaucoma patients.

To assess the influence of visually significant cataract on the measurement of nerve fibre layer thickness by scanning laser polarimetry (GDx) in glaucoma patients undergoing phacoemulsification cataract extraction. All subjects with primary glaucoma participating in a prospective trial of glaucoma surgery who subsequently underwent cataract extraction were eligible. A single trained observer using the GDx nerve fibre layer analyser (LDT) performed pre- and post-operative measurements of nerve fibre layer thickness (NFLT). NFLT parameters, best-corrected LogMAR visual acuity, and automated visual fields were assessed before and after phacoemulsification cataract extraction with implantation of an acrylic intraocular lens. A total of 49 subjects were assessed: 22 (45%) had POAG and 29 (55%) PACG; all were Asian (36 (73%) were Chinese), with mean age 67.1 (+/-7.6 SD) and mean 'LOCS III' lens opacity grading 11.4 (+/-3.1 SD). Visual acuity significantly improved (mean LogMAR 0.5 vs 0.15, P<0.0001). Corrected pattern standard deviation (6.1 vs 6.4, P=0.2) and mean deviation (-17.7 dB vs -17.0 P=0.91) were little changed after cataract removal. Pseudo-phakic measurements of NFLT were significantly different from pre-op values. Measures of absolute thickness (including the average thickness, ellipse, ellipse average, superior and inferior averages, superior integral) were significantly greater than preoperative values (all P<0.01), whereas ratios and measures of symmetry (symmetry, superior/nasal) were unchanged (all P>0.1) and 'the number' was smaller (P=0.04). Differences in measured NFLT were most strongly correlated with posterior subcapsular cataract (average thickness, P=0.01). Removal of cataract resulted in greater absolute measurements of NFLT but ratio values were unchanged. Scanning laser polarimetry measurements can change significantly after cataract extraction. New baseline measurements may be required.

Study of ultraminiature sensing coils and the performance of a depolarized interferometric fiber optic gyroscope

A study of the performance of a depolarized fiber optic gyro- scope utilizing miniature single-mode fiber sensing coils is conducted. The study includes the analysis of incorporating long and short Lyot depolarizers coupled with sensing coils with diameters of 0.6 and 2.4 in. The roles of the length of the depolarizers and size of the sensing coils are quantitatively correlated, based on the known material parameters in the theoretical model and the experimental data. Minimum depolarizer requirements necessary to minimize the standard mean deviation of the random drift in miniature interferometric fiber optic gyroscopes are pre- sented. © 2001 Society of Photo-Optical Instrumentation Engineers.

A comparison of optical coherence tomography and retinal nerve fiber layer photography for detection of nerve fiber layer damage in glaucoma

Purpose To compare optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness measurements with established methods for assessment of glaucomatous damage using RNFL photography and visual field testing. Design Cross-sectional study. Participants Fifty-eight eyes of 58 healthy volunteer ocular hypertensive patients, glaucoma suspect patients, and glaucoma patients were included. Methods Optical coherence tomography 3.4-mm diameter circular scans were obtained within 3 months of RNFL photography and standard achromatic visual field testing. Three independent observers graded RNFL photographs using two standardized protocols. For each method, superior and inferior arcuate bundles were scored separately, and interobserver and intraobserver variation was measured. Standard achromatic visual field mean deviation in the superior and inferior hemifields was compared with RNFL damage as assessed by photography and OCT RNFL thickness measurements. Main outcome measures Visual field mean deviation and severity of glaucomatous RNFL damage as assessed by photography. Results Optical coherence tomography RNFL thickness decreased with increasing RNFL damage as assessed by photography using both methods of photographic assessment. Standard achromatic perimetry mean deviation was significantly associated with OCT RNFL thickness ( R 2 = 35%–43%) and RNFL photography severity score ( R 2 = 18%–29%). Conclusions These results suggest that the OCT shows promise for providing quantitative measures of RNFL thickness for diagnosing and monitoring glaucoma.

Concordance of parapapillary chorioretinal atrophy in ocular hypertension with visual field defects that accompany glaucoma development

Objective To determine whether the extent and location of progressive parapapillary chorioretinal atrophy noted in some patients with ocular hypertension are correlated with the extent and location of visual field defects that occur with progression to glaucoma. Study design Retrospective cohort study. Participants Thirty patients with ocular hypertension who had progressive changes of parapapillary atrophy develop before clinically detectable optic disc or visual field damage. Main outcome measures Assessment of changes in the parapapillary atrophy and visual field parameters. Methods Baseline and follow-up optic disc photographs and visual field test results were retrospectively analyzed. The relationship between the extent of parapapillary atrophy observed during the ocular hypertension period and initial visual field abnormalities detected after glaucoma development, as well as their spatial relationship, was statistically analyzed. Results The extent of progressive changes of the parapapillary atrophy detected during the ocular hypertension period was correlated with the extent of changes in the visual field parameters, including corrected pattern standard deviation and mean deviation measured after glaucoma development (Mantel-Haenszel chi-square test, P = 0.026, P = 0.037, respectively). In addition, the visual field abnormalities occurred in the corresponding quadrants of the progressive parapapillary atrophy. Analysis of the spatial relationship revealed that the location of progressive changes of the parapapillary atrophy was concordant with the location of visual field abnormalities in 78% of the quadrants (94 of 120 quadrants) (chi-square test, P = 0.001). Conclusions The extent and location of visual field abnormalities that develop in ocular hypertensive eyes with progression to glaucoma exhibit a concordance with the extent and location of progressive parapapillary atrophy noted in the ocular hypertension period. This suggests the importance of detailed examination of the parapapillary area in ocular hypertensive eyes.

Rescaled Range Analysis of Pluviometric Records in Northeast Brazil

We investigate whether the rainfall distribution of a drought prone region is characterized by different scaling properties in comparison to those in temperate regions of the world. We present a Rescaled Range (R/S) analysis of precipitation time series for 21 stations in northeast Brazil. In order to avoid the inclusion of short term variability, the data were smoothed by a moving average procedure. Three different algorithms were applied to the data: the empirical procedure proposed by Hurst; the evaluation of the standard mean deviation around the average profile; the evaluation ofthe mean deviation around the best fit line. The latter two methods have also been used for the evaluation of the nature of surface irregularities (rugosity) in surface profiles. The results obtained by the R/S method point to an average value H=0.709 > 0.5. This value indicates that the records show a degree of persistence quite close to that found for 10 stations in Spain. It also shows that drought occurrence does not alter the persistence of the rainfall distribution.