Which term is described as the inability to focus different meridians simultaneously?

Which term is described as the inability to focus different meridians simultaneously?

• A. Nearsightedness
• B. Astigmatism
• C. Presbyopia
• D. Hyperopia

Answer: (A)

Astigmatism is the condition described. It happens when the eye’s curvature isn’t uniform, so different meridians (directions) bend light by different amounts. Because vertical and horizontal meridians have different focal lengths, light from a point of light doesn’t land on a single point on the retina. Instead, you get two focal lines, causing vision to be blurred or distorted at all distances. Corrective lenses with cylindrical power (toric lenses) or refractive surgery can equalize the focusing power across meridians. For contrast: nearsightedness (myopia) means distant objects are blurry; farsightedness (hyperopia) means near objects are blurry; presbyopia is age-related loss of the eye’s ability to focus on close objects. These describe overall refractive error, not differing focalities along meridians.

Astigmatism is the condition described. It happens when the eye’s curvature isn’t uniform, so different meridians (directions) bend light by different amounts. Because vertical and horizontal meridians have different focal lengths, light from a point of light doesn’t land on a single point on the retina. Instead, you get two focal lines, causing vision to be blurred or distorted at all distances. Corrective lenses with cylindrical power (toric lenses) or refractive surgery can equalize the focusing power across meridians.

For contrast: nearsightedness (myopia) means distant objects are blurry; farsightedness (hyperopia) means near objects are blurry; presbyopia is age-related loss of the eye’s ability to focus on close objects. These describe overall refractive error, not differing focalities along meridians.