Question

The thickness of the cornea is measured using

• A. Schiotz tonometer
• B. Keratometer
• C. Pachymeter
• D. Aesthesiometer

Hint:

Match each instrument to what it is designed to measure — pressure, curvature, thickness, or sensation.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
This is a straightforward instrument-identification question — it asks which device is used to measure corneal thickness.

Step 2: Key Concept or Approach:
Corneal thickness (central corneal thickness in particular) is an important measurement before refractive surgery, in glaucoma risk assessment, and in evaluating corneal oedema. The dedicated instrument for this purpose is the pachymeter, which can be ultrasonic or optical.

Step 3: Working Through the Options:
A Schiotz tonometer measures intraocular pressure by indentation, not corneal thickness. A keratometer measures the curvature of the anterior corneal surface, used mainly for fitting contact lenses and calculating intraocular lens power, not thickness. A pachymeter is specifically designed to measure corneal thickness, either by ultrasound probe contact or by optical (Scheimpflug or OCT-based) methods. An aesthesiometer measures corneal sensation, not thickness.

Step 4: Conclusion:
Corneal thickness is measured using a pachymeter.