Trabeculectomy and optic nerve head topography.

The objective of the present study was to evaluate changes in optic nerve head parameters, measured by confocal laser tomography, before and after trabeculectomy in order to identify outcome measures for the management of glaucoma. The optic nerve head of 22 eyes (22 patients) was analyzed by confocal laser tomography with the Heidelberg retinal tomogram (HRT) before and after trabeculectomy. The median time between the first HRT and surgery was 4.6 months (mean: 7.7 +/- 8.3) and the median time between surgery and the second HRT was 10.8 months (mean: 12.0 +/- 6.8). The patients were divided into two groups, i.e., those with the highest (group A) and lowest (group B) intraocular pressure (IOP) change after surgery. Differences in the 12 standard topographic parameters before and after surgery for each group were evaluated by the Wilcoxon signed rank test and the differences in these parameters between the two groups were compared by the Mann-Whitney rank sum test. Multiple regression analysis was used to evaluate the influence of the change in IOP (DeltaIOP and DeltaIOP%) and the changes in the other parameters. There were significant differences in the HRT measures before and after surgery in group A only for cup volume. In group B, no parameter was statistically different. The changes in group A were not significantly different than those in group B for any parameter (P > 0.004, Bonferroni correction for multiple comparisons). DeltaIOP and DeltaIOP% had a statistically significant effect on Delta cup disk area, Delta cup volume and Delta mean cup depth. Changes in cup shape size were influenced significantly only by DeltaIOP. Some optic disc parameters measured by HRT presented a significant improvement after filtering surgery, depending on the amount of IOP reduction. Long-term studies are needed to determine the usefulness of these findings as outcome measures in the management of glaucoma.

Trabeculectomy and optic nerve head topography

The objective of the present study was to evaluate changes in optic nerve head parameters, measured by confocal laser tomography, before and after trabeculectomy in order to identify outcome measures for the management of glaucoma. The optic nerve head of 22 eyes (22 patients) was analyzed by confocal laser tomography with the Heidelberg retinal tomogram (HRT) before and after trabeculectomy. The median time between the first HRT and surgery was 4.6 months (mean: 7.7 ± 8.3) and the median time between surgery and the second HRT was 10.8 months (mean: 12.0 ± 6.8). The patients were divided into two groups, i.e., those with the highest (group A) and lowest (group B) intraocular pressure (IOP) change after surgery. Differences in the 12 standard topographic parameters before and after surgery for each group were evaluated by the Wilcoxon signed rank test and the differences in these parameters between the two groups were compared by the Mann-Whitney rank sum test. Multiple regression analysis was used to evaluate the influence of the change in IOP (deltaIOP and deltaIOP percent) and the changes in the other parameters. There were significant differences in the HRT measures before and after surgery in group A only for cup volume. In group B, no parameter was statistically different. The changes in group A were not significantly different than those in group B for any parameter (P > 0.004, Bonferroni correction for multiple comparisons). deltaIOP and deltaIOP percent had a statistically significant effect on delta cup disk area, delta cup volume and delta mean cup depth. Changes in cup shape size were influenced significantly only by deltaIOP. Some optic disc parameters measured by HRT presented a significant improvement after filtering surgery, depending on the amount of IOP reduction. Long-term studies are needed to determine the usefulness of these findings as outcome measures in the management of glaucoma.

Influence of keratometric readings on comparative intraocular pressure measurements with Goldmann, Tono-Pen, and noncontact tonometers.

PURPOSE: To evaluate the influence of keratometric measurements on the concordance of intraocular pressure (IOP) readings with three applanation tonometers. PATIENTS AND METHODS: The IOPs of 404 eyes of 202 patients from a general eye clinic were measured by Goldmann, Tono-Pen XL, and noncontact Nidek NT 2000 tonometers. Differences in the IOP measurements between Goldmann and the other two tonometers (deltaIOPG-TP and deltaIOPG-NCT) were analyzed in the overall group and within three subgroups based on keratometry measures: flatter, intermediate, and steeper corneas (quartiles as cut-off points). Regression analysis of deltaIOP and keratometry measures was also performed. Right and left eyes were analyzed separately. RESULTS: The IOP readings taken with the Goldmann tonometer were significantly higher than those taken with either of the other two tonometers within the overall study population. The deltaIOP within the three keratometric subgroups was not statistically significant except for deltaIOPG-TP in the right eyes. Regression analysis showed that keratometry and deltaIOPG-TP and deltaIOPG-NCT had a significant but very weak coefficient of correlation in the right eye, but not in the left. CONCLUSION: Corneal curvature within the normal range does not have a clinically significant influence on the concordance of IOP readings obtained with Goldmann and Tono-Pen or noncontact tonometers.

Families, migration and adjusting to disequilibrium.

"Unlike the case for individual migration, education may reduce the migration of families by enhancing their ability to adjust to local disequilibrium and stay at their preferred location. Estimates of family migration probabilities in Costa Rica support this hypothesis."

An application of parity progression ratios to developing countries.

PIP: Individual data from the 1973 Costa Rican census are used to estimate both the probability of another birth and its spacing. Both these dependent variables are estimated as a function of parity, the age of the wife, and selected socioeconomic variables. The dependent variables are estimated for families that had a birth approximately 5 years prior to the census. The probability that a woman will have another birth varies significantly with the selected socioeconomic variables. The spacing of that birth is not significantly explained by these variables. A 10% probability sample of households was taken from the 1973 census. A data set was created using the number and ages of the household's own children. The methods used to analyze the data are ordinary least squares (OLS) and tobit analysis. For child spacing, OLS was used to estimate the spacing of a birth given that the woman had another child. All the coefficients had the usual signs except for husband's education, where the coefficient was almost zero. While the regression as a whole was significant, only the wife's education and the wife's working hours were significantly different from zero. Most surprising was the insignificance of the location variable. While there was some evidence that rural women, other things being equal, had their children 22 days closer together than urban women, the results were not statistically significant. The results indicated that Costa Rican women may not vary their child spacing as their socioeconomic conditions change. The results did not rule out the possibility of delayed child spacing as a response to a downturn in business conditions, for the period under study was one of steadily rising income. And, OLS was not the appropriate estimating method. Yet, the results were sufficiently discouraging to concentrate on birth probabilities. Unlike child spacing, the probability that a woman will have another child changed dramatically with socioeconomic conditions. The probability that a woman will have another birth for any given vector of socioeconomic variables was very similar for tobit and OLS. The results implied considerable differences in fertility. Changes in location, education, and the wife's age all exerted substantial influences on completed parity. An increase in the husband's and wife's education of 5 years each implied a reduction of .1 in each parity progression ratio. Differences between urban and rural locations implied a reduction of more than .1 in parity progression ratios. An increase of just 3 years in the wife's age reduced parity progression ratios by .05.^ieng