Astigmatism occurs because of what condition?

• A. A convex lens diverges light.
• B. The cornea is more steeply curved in one direction than in the other.
• C. The retina has irregularities.
• D. The pupil size affects refraction.

Answer: (B)

Astigmatism happens when the cornea is not equally curved in all directions. If one direction is steeper, light is bent more along that axis than along the perpendicular axis. This causes light to focus at two different points on the retina instead of one, leading to blurry or distorted vision. The standard description is that the cornea has a steeper curvature in one meridian than in the other, which is why this option best fits. Other ideas, like a strange retina, a lens that diverges light, or pupil size changing refraction, don’t describe the uneven curvature that causes the blur characteristic of astigmatism.