This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
[{'content': 'Tonography helps you to determine – \nSelect and explain. \nA. The rate of formation of aqueous, B. The facility of outflow of aqueous, C. The levels of intraocular pressure at different times., D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: There are two similar terms.\n\nTonography\n\nTonography is a non-invasive technique for determining the facility of aqueous outflow (C-value).\nFacility of aqueous outflow is estimated by placing schiotz tonometer on the eye for 4 minutes.\nBeside tonography, other methods to measure the facility of aqueous outflow (C-value) are perfusion method and suction cup method.\nThe average C-value is 0.28 ± 0.05 1/ min / mmHg. Most glaucoma patients have C-value less than 0.17.\n\nTonometery \n\nTonometry is the assessment of the intraocular pressure of the eye.\nTherefore, it is used in the diagnosis of glaucoma and for monitoring the treatment response in glaucoma.', 'role': 'assistant'}]