Comparatively, in against-the-rule astigmatism, the horizontal meridian stays close to 180˚, which is steeper than the vertical meridian. Against-the-rule astigmatism is common in the elderly.

When you have astigmatism, some of the bold lines will look blurrier than others ... have “with-the-rule” astigmatism. If the horizontal lines pop out, then you have “against-the-rule ...

“You first need to determine the astigmatism. There are a variety of diagnostic methods you can use, and you want to choose more than one ... either be with the rule or against the rule.

They both measured about 1.2 D of total astigmatism, meaning the posterior surface only contributed about 0.3 D against-the-rule. Because ... posterior astigmatism than what was actually measured ...