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).
Corneal and Refractive Astigmatism in Adults: A Power Vectors Analysis
Purpose. In this article, we examine the relationship between corneal and refractive astigmatism (including with the rule, against-the-rule, and oblique astigmatism) in an adult population using power vectors. Methods. Refractive and keratometric measures of astigmatism were conducted on right eyes of 105 white subjects aged 18 to 59 years. We performed a linear regression of refractive astigmatic error on corneal astigmatism, using the J0 and J45 components of the astigmatism. Results. We obtained a statistically significant regression relationship between the corneal (C) and refractive (R) astigmatism for both J0 and J45 components, namely, RJ0 = 1.07 × CJ0 − 0.28; and RJ45 = 1.46 × CJ45 + 0.03. This results is a kind of generalized Javal rule for an adult population, because it is extended to include oblique astigmatism. We also found that the internal astigmatism is against-the-rule and uniform in our sample. Conclusions. This vector-based approach is equivalent to the traditional Javal rule, but it has the ability to make predictions about oblique astigmatism, rendering it more general and more accurate.
Solidarity. Reflections on an Emerging Concept in Bioethics. Summary
1. References to solidarity are currently on the increase in public discourse. In the UK and beyond, during economic crises and in a political climate where many feel that mutual assistance has lost currency, calls for a new and forceful emphasis on the meaning of solidarity are increasingly heard. Such appeals to solidarity are inevitably linked to ideas about how societies function, and about how and where the boundary between individual, familial, communal and societal spheres of responsibilities should be drawn.