Which of the following tonometer can be used in diseased cornea
**Core Concept**
The question is testing the ability to identify a tonometer that can be used in cases of diseased cornea, which poses a challenge in obtaining accurate intraocular pressure measurements. This requires an understanding of the different types of tonometers and their indications.
**Why the Correct Answer is Right**
The non-contact tonometer is a type of tonometer that uses a puff of air to estimate intraocular pressure. It does not require physical contact with the cornea, making it suitable for use in cases of diseased cornea, such as corneal ulcers or edema. This is because the air puff does not have to come into direct contact with the cornea, reducing the risk of further damage.
**Why Each Wrong Option is Incorrect**
**Option A:** The applanation tonometer is a contact tonometer that uses a plunger to flatten a small area of the cornea to measure intraocular pressure. It is not suitable for use in cases of diseased cornea due to the risk of further corneal damage.
**Option B:** The indentation tonometer measures intraocular pressure by indenting the cornea with a plunger. Like the applanation tonometer, it is a contact device and not suitable for use in cases of diseased cornea.
**Option C:** The pneumatonograph measures intraocular pressure using a device that inflates a small balloon to flatten the cornea. While it is a non-contact device, it requires the use of a numbing drop, which may not be suitable for patients with certain corneal conditions.
**Clinical Pearl / High-Yield Fact**
When dealing with a patient with a diseased cornea, it's essential to use a non-contact tonometer to avoid further corneal damage. The non-contact tonometer is a safe and reliable option in such cases.
**Correct Answer: B. Non-contact tonometer**