Which part of the eye can cause blurred vision and may result in astigmatism when abnormally shaped?

• A. Cornea
• B. Lens
• C. Iris
• D. Pupil

Answer: (A)

The cornea is the part that matters here. It’s the transparent front surface of the eye that does most of the eye’s bending of light. If the cornea isn’t equally curved in all directions—being more curved in one axis than the perpendicular axis—light rays don’t meet at a single point on the retina. Instead, they focus at multiple points, causing blurred vision and a distortion called astigmatism. The lens can influence focus as well, but astigmatism most often comes from an irregular corneal shape. The iris and pupil don’t cause this refractive distortion; the pupil just controls how much light gets in, and the iris mainly moves to adjust pupil size.