What characterizes against-the-rule astigmatism?

Against-the-rule astigmatism is characterized by a steeper curve at the horizontal meridian. This means that the axis of steepness is oriented horizontally, which is the opposite of with-the-rule astigmatism, where the steeper curve is vertical. In clinical practice, this distinction is crucial for lens design and fitting because the orientation of the astigmatism affects how light is refracted through the lens, ultimately influencing the patient's vision. When identifying against-the-rule astigmatism, the practitioner looks for this specific curvature pattern to ensure accurate correction with the appropriate prescription.

The other options do not align with the characteristics of against-the-rule astigmatism, as they either describe other forms of astigmatism or pertain to demographic observations that do not directly pertain to the curvature patterns being assessed.