Refractive, corneal, and ocular residual astigmatism: distribution in a German population and age dependency—the Gutenberg Health Study
Dear editor, We would like to thank Dr. Alpins and Mr. Stamatelatos [1] for their interest in our study [2]. Indeed, analysis of astigmatism is a challenging approach and these authors highly contributed to pave its path [3, 4]. In addition to the specific characteristics of astigmatism including amount and orientation, there are (unfortunately) different notations: while in most English-spoken countries a positive notation of astigmatism is in use (cylinder in plus diopters), Germany and other European countries commonly use negative measures of astigmatism (cylinder in minus diopters).While the absolute amount of astigmatism is the same, the orientation has a shift of 90° and spherical power is different. This is in contrast to measurement of velocity, an analogy been drawn byDr. Alpins andMr. Stamatelatos [1]: velocity is defined by the ratio of two units of the International System of Units (SI).
Refractive, corneal and ocular residual astigmatism: distribution in a German population and age-dependency - the Gutenberg health study
PurposeWorldwide, the most frequent cause of visual impairment is uncorrected refractive error. This analysis focused on the distribution and associations of refractive, corneal and ocular residual astigmatism.MethodsAs part of the Gutenberg Health study, a population-based cross-sectional study was conducted in the general population of Germany. A comprehensive ophthalmological examination including refraction, tonometry, and Scheimpflug imaging of the anterior cornea (Pachycam) was performed. In addition to the magnitude and type (with-the-rule, against-the-rule, oblique) of the refractive or corneal astigmatism, we calculated the vector components (J0, J45) of both astigmatisms and calculated the ocular residual astigmatism. We performed multiple quantile regression analysis to evaluate the factors associated with refractive, corneal and ocular residual astigmatisms.ResultsA total of 13,558 subjects (49% female) with a mean age of 54.0 years (range 35–74 years) were included in this study. The prevalence of refractive astigmatism (>1.0D) was 13.0% in right eyes and 12.0% in left eyes, and 85% of these subjects wore spectacles. The distribution of refractive astigmatism showed a two-peak distribution with high astigmatism for with-the-rule and against-the-rule astigmatism. The associated factors were corneal curvature, age and sex for the different astigmatisms (p < 0.001).ConclusionsWe analyzed the prevalence of different astigmatisms within a European population. We confirmed a shift with aging from with-the-rule to against-the-rule astigmatism to refractive and corneal astigmatism. Astigmatism has a large impact on visual perception; more than 85% of people with astigmatism over one diopter wore glasses for distance vision.
The MR-TOF-MS isobar separator for the TITAN facility at TRIUMF
At TRIUMF’s Ion Trap for Atomic and Nuclear Science (TITAN) a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) will extend TITAN’s capabilities and facilitate mass measurements and in-trap decay spectroscopy of exotic nuclei that so far have not been possible due to strong isobaric contamination. This MR-TOF-MS will also enable mass measurements of very short-lived nuclides (half-life > 1 ms) that are produced in very low quantities (a few detected ions overall). In order to allow the installation of an MR-TOF-MS in the restricted space on the platform, on which the TITAN facility is located, novel mass spectrometric methods have been developed. Transport, cooling and distribution of the ions inside the device is done using a buffer gas-filled RFQ-based ion beam switchyard. Mass selection is achieved using a dynamic retrapping technique after time-of-flight analysis in an electrostatic isochronous reflector system. Only due to the combination of these novel methods the realization of an MR-TOF-MS based isobar separator at TITAN has become possible. The device has been built, commissioned off-line and is currently under installation at TITAN.