Which is an example of against-the-rule astigmatism?

Against-the-rule astigmatism occurs when the steepest meridian of the cornea is oriented in a horizontal position, typically at 0 to 30 degrees and 150 to 180 degrees, while the flattest meridian is oriented vertically, at 90 degrees. In the given example, the prescription indicates that one meridian is at 180 degrees with a power of 44.00, and the other is at 90 degrees with a power of 43.00. This aligns with the definition of against-the-rule astigmatism because the more positive power (which is steeper) is located in the horizontal meridian (180 degrees), and the less positive power is in the vertical meridian (90 degrees).

This type of astigmatism can have implications for how a contact lens is designed or fitted since the lens needs to accommodate the different curvatures effectively to optimize vision. Understanding the orientation of the astigmatism is crucial for providing the appropriate corrective lenses.