Question

A person looking at a person wearing a shirt with a patterncomprising vertical and horizontal lines is able to see the verticallines more distinctly than the horizontal ones. What is this defect due to? How is such a defect of vision corrected?

Answer 1

Since, the person is able to see vertical lines more distinctly than horizontal lines, the refracting system (cornea and eye-lens) of the eye is not working in the same manner at different planes. This defect is known as astigmatism. The person’s eye has sufficient curvature in the vertical plane hence; sharp images of the vertical lines are formed on the retina. However, the curvature in the horizontal plane is not enough for images to form sharply at the retina so the horizontal lines appear blurred.

To correct this defect, cylindrical lenses can be used.