Texas A&M University (TAMU) BIOL 320 Integrated Human Anatomy and Physiology II Lab Practical 1 Practice Test

Astigmatism happens when the eye’s refracting surfaces aren’t equally curved in all directions. If the cornea or the lens has different curvatures in different meridians, light rays entering the eye don’t all come to the same point on the retina. One direction focuses nearer and the perpendicular direction focuses farther, so the image is blurred or distorted at all distances. This is why blurred vision occurs specifically when the cornea or lens has uneven curvature. Other causes described in the options—color deficiencies, changes in pupil size, or aging of the lens—produce blurred vision for different reasons (color vision issues, depth-of-field changes, or presbyopia/cataracts) and don’t capture the defining feature of astigmatism: irregular curvature of the eye’s focusing surfaces. Often this condition is corrected with lenses that balance focus along the different meridians.