Question

Second sight is seen in which type of cataract?

• A. Nuclear cataract
• B. Cortical cataract
• C. Zonular cataract
• D. Punctate cataract

Hint:

Which cataract raises the lens refractive index and induces index myopia?

Answer 1

The Correct Option is A

Step 1: Second sight refers to a temporary improvement in near vision that an older person with a developing nuclear cataract may notice, sometimes allowing them to read without their reading glasses.

Step 2: The mechanism is an index myopia. As the lens nucleus scleroses and hardens, its refractive index rises. This increases the converging power of the lens, shifting the eye towards myopia, so near objects come into focus more easily.

Step 3: This is therefore a feature specific to nuclear sclerotic cataract, making nuclear cataract the correct answer.

Step 4: Cortical, zonular, and punctate cataracts involve the cortex, the zonular lamellae, or scattered dot opacities respectively and do not raise the nuclear refractive index, so they do not produce the second sight phenomenon.