Give the biological/technical term for the following:
A defect in our eye in which some parts of the object are in focus while the other parts are blurred.
Topic: Astigmatism
Answer
ASTIGMATISM.
Astigmatism is caused by an IRREGULAR CURVATURE of the cornea or the lens. Because the surface is not evenly curved, light entering in one plane is focused at a different point from light entering in another, so parts of the image are sharp while other parts are blurred at the same time.
That simultaneous sharp-and-blurred quality is exactly what the question describes, and it is what distinguishes astigmatism from the other two common defects: MYOPIA (short sight) — the whole distant image is blurred; the eyeball is too long. Corrected by a CONCAVE lens. HYPERMETROPIA (long sight) — the whole near image is blurred; the eyeball is too short. Corrected by a CONVEX lens. ASTIGMATISM — PART of the image is blurred at any distance. Corrected by a CYLINDRICAL lens.
THE KEY WORDS in the question are "some parts... while the other parts". A defect affecting the WHOLE image cannot be the answer.