This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy, Development and clinical examination, Subject name: Ophthalmology
[{'content': "Increased intraocular tension can be diagnosed by \nSelect and explain. \nA. Tonometer, B. Pachymeter, C. Placido's disc, D. Keratometer", 'role': 'user'}, {'content': 'Answer: A \nExplanation: The intraocular pressure (IOP) is measured with the help of an instrument called tonometer. Two basic types of tonometers available are: indentation and applanation. Indentation (impression) tonometry is based on the fundamental fact that a plunger will indent a soft eye more than a hard eye. The concept of applanation tonometry was introduced by Goldmann is 1954. It is based on Imbe- Fick law which states that the pressure inside a sphere (P) is equal to the force (W) required to flatten its surface divided by the area of flattening (A); i.e., P = W/A. Reference: AK khurana 7th edition', 'role': 'assistant'}]