Biomedical subjects

L Zangwill

Publications and source records attributed to L Zangwill.

31 records · Page 2Linked to original sources

PubMed1997

Reproducibility of retardation measurements with the nerve fiber analyzer II.

PURPOSE: To evaluate the reproducibility of a scanning laser polarimeter, the Nerve Fiber Analyzer II (NFA II, Laser Diagnostic Technologies, San Diego, CA, U.S.A.). METHODS: Five independent retardation maps of the peripapillary retina of five normal eyes were acquired by three experienced operators (including V.S.G.) on each of three separate days for a total of 45 retardation maps per patient. Two methods of image processing, one using a baseline image and another using the individual scans, were used to compare the reproducibility of three summary measures, average retardation, integral, and retardation ratio. RESULTS: The average standard deviation (and its 95% confidence interval) of average retardation within a 10-pixel-width-band of the 9 baseline images was 0.43 degree (0.36-0.51 degree) with a mean coefficient of variation of 4.2% (3.8-4.5%). In a random effects model, each of the three retinal nerve fiber layer (RNFL) summary measures varied significantly by patient (p < 0.016), but not by operator (p > 0.19), or operator by patient interaction (p > 0.524). In addition, there was small, but statistically significant day-by-operator-within-patient (intraobserver) variation in the random effects model. CONCLUSIONS: These results suggest that the NFA II provides reproducible measurements and that, on average, measurements obtained by separate operators on different days are similar.

Adult↗

PubMed1996

Change in optic disk topography after trabeculectomy.

PURPOSE: To investigate the relationship between optic disk topography and intraocular pressure before and after trabeculectomy with confocal scanning laser ophthalmoscopy. METHODS: The eyes of 49 consecutive patients undergoing trabeculectomy at a university-based glaucoma practice underwent preoperative and postoperative imaging using a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). Three images of one eye of each patient were obtained with a 15-degree field of view. Preoperative images were obtained approximately 2 months before surgery (mean +/- SD, 2.4 +/- 1.6 months). Postoperative images were obtained at least 3 months after surgery (mean, 4.5 +/- 2.6 months). RESULTS: Mean preoperative intraocular pressure, postoperative intraocular pressure, and percent change in intraocular pressure respectively were 23.1 +/- 6.8 mm Hg, 12.7 +/- 7.1 mm Hg, and 43.8% +/- 29.9%. A significant association (P < .01) was found between percent decrease in intraocular pressure and decreases in cup area, cup volume, and cup/disk area ratio as well as between percent decrease in intraocular pressure and increases in rim area, rim volume, mean height contour, retinal cross-section area, and height in contour. Between 11.7% and 31.2% of the variability (R2) in these parameters was explained by the percent change in intraocular pressure. Topography changes were more strongly associated with percent change than with mean change in intraocular pressure. We found no association between percent decrease in intraocular pressure and reference plane height or maximum cup depth. CONCLUSIONS: Changes in optic nerve topography were associated with reduction in intraocular pressure after trabeculectomy.

Academic Medical Centers↗

PubMed1996

Ranked-segment distribution curve for interpretation of optic nerve topography.

PURPOSE: The objective of this article was to evaluate whether a new method for analysis of optic nerve topography, the ranked-segment distribution (RSD) curve, can differentiate between normal and glaucoma eyes. METHODS: Topographic optic nerve parameters of 39 normal subjects aged 50-79 years were measured using a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). Disc parameters were determined from the mean topography of three images of each eye obtained with a 15 degrees field of view. Rim area and retinal nerve fiber layer cross-section area were measured in 36 segments (each of 10 degrees) around the disc margin. For each parameter, the 36 segments were ranked in descending order and graphically depicted as the RSD curve. In normal eyes, the fifth percentile values for each of the ranked segments were calculated and graphed to compare with glaucoma eyes within the same age group. Evaluation of RSD curves was done automatically with a computer program using predefined criteria. Three primary open-angle glaucoma cases are presented to demonstrate the RSD curve method. RESULTS: In these three glaucoma eyes, RSD curves demonstrated defects more consistently than stereoscopic disc photography, nerve fiber layer photography, and computerized visual field testing. In two cases, RSD curves differentiated between diffuse and localized defect as well as demonstrated the locations of the defects. CONCLUSION: The RSD curve technique may assist in the interpretation of topographic optic nerve parameters and in the detection of glaucomatous optic neuropathy.

Adult↗

PubMed1995

Scanning laser polarimetry to measure the nerve fiber layer of normal and glaucomatous eyes.

PURPOSE: To determine whether retardation (change in polarization) measurements of healthy subjects and glaucoma patients obtained by using a confocal scanning laser polarimeter correspond to known properties of the nerve fiber layer. METHODS: A polarimeter, an optical device used to measure the change in linear polarization of light (retardation), was interfaced with a scanning laser ophthalmoscope to obtain retardation data at 65,536 locations (256 x 256 pixels) in a study of normal subjects and patients with primary open-angle glaucoma. To validate the instrument, we compared our measurements with known properties of the human retinal nerve fiber layer in 105 normal subjects. Additionally, we compared retardation measurements in eyes of 64 normal subjects and 64 age-matched glaucoma patients treated in a referral practice. RESULTS: In normal eyes, mean (+/- S.D.) peripapillary retardation was highest in the superior and inferior arcuate regions and lowest in the temporal and nasal regions, 12.0 +/- 1.9, 13.1 +/- 2.0, 7.0 +/- 1.8, and 7.0 +/- 1.6 degrees, respectively. Retardation decreased toward the periphery and was lower over blood vessels. In normal eyes, retardation decreased with increasing age in the superior and inferior regions. Mean retardation was statistically significantly higher among normal eyes than glaucoma eyes in the inferior and superior regions but not in the temporal or nasal areas. CONCLUSIONS: Scanning laser polarimetry provides quantitative measurements that correspond to known properties of the retinal nerve fiber layer in normal and glaucomatous eyes.

Adolescent↗

PubMed1995

Agreement between clinicians and a confocal scanning laser ophthalmoscope in estimating cup/disk ratios.

PURPOSE: We assessed agreement between cup/disk ratio measurements obtained by glaucoma expert evaluation of stereoscopic photographs of the optic disk and those obtained with a confocal scanning laser ophthalmoscope. METHODS: Three glaucoma experts estimated vertical and horizontal cup/disk ratios from stereoscopic photographs of 15 normal subjects and 15 patients with glaucoma. These estimates were compared to vertical, horizontal, and area cup/disk ratios measured with a confocal scanning laser ophthalmoscope. Intraobserver and interobserver agreements were also estimated. RESULTS: Agreement between clinicians and the confocal scanning laser ophthalmoscope varied by clinician. Agreement was moderate to substantial for vertical cup/disk ratio and fair to moderate for horizontal cup/disk ratio; kappas ranged from 0.57 to 0.72 and from 0.21 to 0.55, respectively. The mean confocal scanning laser ophthalmoscope area cup/disk ratio measurements were smaller than each clinician's mean vertical and horizontal cup/disk ratio estimates; differences ranged from 0.10 to 0.24 and from 0.06 to 0.16, respectively. Differences were smaller between clinician estimates and instrument measurements of horizontal and vertical cup/disk ratios of patients with glaucoma than normal subjects. CONCLUSIONS: These results demonstrate good agreement between confocal scanning laser ophthalmoscope measurements and clinician estimates of the vertical cup/disk ratios from stereoscopic photographs, particularly of patients with glaucoma. However, as differences between clinician and instrument estimates of cup/disk ratios were found, new quantitative criteria must be established for characterizing a disk as glaucomatous using confocal scanning laser ophthalmoscopy.

Adult↗

PubMed1995

Association between quantitative nerve fiber layer measurement and visual field loss in glaucoma.

PURPOSE: To evaluate the association between quantitative nerve fiber layer measurements and visual field loss in patients with primary open-angle glaucoma. METHODS: Quantitative retinal nerve fiber layer measurements were obtained in 53 patients with primary open-angle glaucoma by using confocal scanning laser ophthalmoscopy (cross-section area) and confocal scanning laser polarimetry (retardation ratio). For each eye, three images were obtained with each instrument. An image that was the mean of those three was created and used in all analyses. We investigated the association between global, regional, and hemifield differences in retinal nerve fiber layer measurements and visual field loss with linear regression techniques. RESULTS: The retardation ratio decreased with increasing mean visual field loss, measured both globally and regionally; R2 (the amount of variation explained by the model) ranged from 8% to 21%. Retinal nerve fiber layer cross-section area was not significantly associated with global measures of visual field loss. The inferior visual field mean deviation increased with decreasing superior retinal nerve fiber layer cross-section area (R2 = 8.2%, P = .04); superior visual field mean deviation was not associated with inferior retinal nerve fiber layer cross-section area (R2 = 2.6%, P = .25). Hemifield differences in visual field mean deviation increased with increasing hemifield differences in retinal nerve fiber layer cross-section area (R2 = 20.0%, P < .001), but not with retardation ratio (R2 = 0.9%, P = .48). CONCLUSIONS: Quantitative measures of the retinal nerve fiber layer using both confocal scanning laser ophthalmoscopy and confocal scanning laser polarimetry were correlated with visual field loss in glaucoma patients.

Aged↗

PubMed1995

Undernutrition among Bedouin Arab children: a follow-up of the Bedouin Infant Feeding Study.

After 10 y of urban settlement, 680 Bedouin Arab children, who had had anthropometric assessment from birth (1981-1982) through early childhood, were reassessed in 1991-1992 to compare the rates of stunting in early and later childhood as well as to describe the factors influencing current height-for-age. Stunting had dropped from 32.7% at 18 mo to 7.2% at 10 y in the 1981 birth cohort and dropped from 17.5% at 9 mo to 8.2% at 9 y in the 1982 birth cohort. Based on a multiple-linear-regression analysis, height in early childhood and maternal height were statistically significantly and positively associated with current mean height-for-age in both cohorts. In the 1982 cohort socioeconomic status in early childhood was positively and current family size was negatively and significantly associated with current mean height-for-age. Thus, conditions that were present in early childhood had the largest influence on current height. In 1992, 10% and 6% of the infant siblings of the 1981 and 1982 cohorts, respectively, were stunted compared with 17% and 1% of the siblings aged 1-2 y of the respective cohorts. Therefore, the high rates of early childhood stunting in 1981-1982 appeared to be a birth cohort-specific phenomenon.

Child↗

PubMed1992

Diurnal intraocular pressure variations: an analysis of 690 diurnal curves.

Out of a total of 2272 diurnal curves (DC) of intraocular pressure (IOP) obtained from 1178 patients 690 first curves of the right eye of all patients were analysed. For each DC there were 4-6 IOP readings taken between 8 am and 6.30 pm of the same day. The patients' diagnosis, age, sex, type of IOP lowering medication, diabetes, and the calendar month of the year were recorded. In 40% of cases the highest IOP was found at the earliest morning measurement with some 65% of peaks occurring before noon. The lowest IOP measurement showed no specific predilection for any particular time of the day. These findings were true for all diagnosis groups. The mean range of IOP fluctuation during the DC was 5.0 mm Hg in normals, 5.8 mm Hg in patients with open angle glaucoma (OAG), and 6.8 mm Hg in patients with ocular hypertension (OHT). Patients treated with timolol had a lower mean IOP fluctuation range than those on other types of IOP lowering treatment. No association was found between all other parameters examined and the diurnal IOP distribution.

Adrenergic beta-Antagonists↗

PubMed1991

The Bedouin Infant Feeding Study: study design and factors influencing the duration of breast feeding.

A longitudinal study of infant feeding practices, growth and morbidity among Bedouin Arab infants residing in the Negev, Israel, was conducted during a 3-year period (1981-1983). Follow-up samples were restricted to healthy newborns. The majority of newborns are breast fed at birth but, by 2 months, 50% are also introduced to a milk supplement. Based on the bivariate analysis using the logrank test to examine the factors associated with exclusive versus partial breast feeding during the first 6 months, those born during the wet cool months are exclusively breast fed longer than those born during the dry season. More traditional women, living in tents rather than houses or huts, exclusively breast feed for at least 6 months. In a multiple logistic regression model, parity, house type and birth season are independently associated with the odds of exclusively breast feeding for the first 6 months of life. Factors influencing the duration of any breast feeding for the first 18 months include: house type, place of residence, birthweight, and whether the infant was stunted at 6 months.

Animals↗

PubMed1988

Epidemiology of retinal vein occlusion and its association with glaucoma and increased intraocular pressure.

A population-based study found an overall incidence rate of symptomatic retinal vein occlusion (RVO) in a 4-year period to be 2.14 per 1,000 in the 40 years and over age group. When cases found among glaucoma clinic patients were separated from the remainder of the population there was marked difference in the incidence rate of RVO in the same time period (1.85 and 17.3 per 1,000, respectively). The rate of RVO increased significantly (p less than 0.001) with age in the general population from 0.93 per 1,000 among persons under 64 years of age to 5.36 per 1,000 among persons over 65. The increase in the rate of RVO by age was less dramatic in the glaucoma clinic population. The two populations also differed in the frequency of the occlusion type: the ratio of the rate of branch vein occlusion to central vein occlusion was 3.2:1 in the general population, but equally distributed in the glaucoma clinic population. Persons with increased intraocular pressure and/or glaucoma were found to have a higher prevalence of RVO than persons with no history of elevated intraocular pressure.

Adult↗

PubMed1987

Epidemiology of intraocular pressure in a population screened for glaucoma.

This study evaluated the association between intraocular pressure and various sociodemographic characteristics, ocular findings, and cardiovascular risk factors in a population screened for glaucoma. A total of 2594 subjects older than 40 years residing in three urban areas of southern Israel participated. Of those screened 6.1% had a raised intraocular pressure (IOP greater than or equal to 21). The mean IOP increased with age, was higher among persons born in Africa or Asia than those born in Europe or America, higher among myopes than hypermetropes and among those with an enlarged cup-disc ratio (CDR). Analysis of variance tests indicated that refractive status, CDR, age, country of birth, and diabetes were each independently associated with IOP. In addition, associations between raised intraocular pressure and age, country of birth, myopia, CDR, diabetes, and glaucoma in the family were found.

Adult↗

PubMed1984

Monitoring of hospital emergency room visits as a method for detecting health effects of environmental exposures.

We excepted from the logs of the adult and children's emergency room at Soroka Hospital Medical Center the number and types of services requested by day for the year 1980. Both total visits and visits for respiratory conditions were examined in order to test whether rain, heat, or pollutants led to increased requests for emergency room care. The total visits for adults were 72,375, of which 1,727 (2.4%) were for selected respiratory conditions. The total visits for children were 19,232, and respiratory conditions were 3,980 (20.7%). There is marked seasonal excess for respiratory visits for children in winter, and a lesser excess for adult respiratory conditions. Non-respiratory conditions and overall visits are higher in summer months. Fewer visits occur on Saturday and on Friday, with the maximum on Sunday. Otitis and bronchitis among children show little day-of-week trends. "High event" days for admissions are determined by fitting a Poisson distribution to the numbers of admissions by day for various respiratory complaints, and we then examine the concordance between these high event days and days with rain, high pollution or temperature. Adult respiratory conditions were more likely to occur on days with high total particulates (TSP) and "respirable" particulates (RSP). When the mean values of RSP and TSP for high asthma and shortness of breath days were compared with a random day for the same month, significant differences were found for RSP for adults, but not for TSP. Natural dust is the more likely cause of this association. Emergency room monitoring should be useful in locations with high levels of man-made pollutants.

Adult↗

PubMedDate not supplied

An analysis of the quality of research reports in the Journal of General Internal Medicine.

Forty-four "original articles" published in the Journal of General Internal Medicine were reviewed using a rating instrument with 13 items developed from previously published standards for the design, analysis, and presentation of medical research. Each item was rated on a four-point (poor-to-excellent) scale. Inter-rater agreement was good (86% agreement; kappa = 0.65). Seven items received excellent or good ratings in 80% or more of the articles, but six problem areas were identified: description of study scope (generalizability), informed consent procedures, reliability assessments, references for statistical procedures or computer programs, and the use of descriptive and comparative statistics. Guidelines for these and other criteria are offered to help researchers prepare clear and informative reports.

Internal Medicine↗