**Core Concept**
Indentation tonometry, also known as applanation tonometry, measures intraocular pressure (IOP) by indenting or flattening a small area of the cornea. The instrument used in indentation tonometry is the Schiotz tonometer, which relies on a plunger to indent the cornea.

**Why the Correct Answer is Right**
The correct answer is related to the principle of indentation tonometry, where a small plunger is used to flatten the cornea. In this method, the amount of indentation is directly proportional to the intraocular pressure. However, the scale reading is inversely related to the IOP. This means that lower scale readings are obtained in eyes with higher intraocular pressure. This occurs because the increased pressure causes a greater indentation of the cornea, resulting in a lower scale reading on the tonometer.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is incorrect because a hard eye (one with a higher scleral rigidity) would require more force to indent the cornea, resulting in a higher scale reading, not a lower one.

**Option C:** This statement is incorrect because low scleral rigidity would result in a lower scale reading, not a higher one. This is because the cornea would be more easily indented, resulting in a lower scale reading.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that indentation tonometry measures intraocular pressure indirectly by measuring the amount of indentation of the cornea. This method is less accurate than applanation tonometry and should be used with caution.

**Correct Answer:**
✓ Correct Answer: B. Lower scale readings are obtained in high intraocular pressure