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': 'Keratometry is useful in measuring – \nSelect and explain. \nA. Corneal curvature, B. Corneal thickness, C. Conical diameter, D. Depth of anterior chamber', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Keratometry\n\nA keratometer, also known as an ophthalmometer, is a diagnostic instrument for measuring the curvature of the anterior surface of cornea. Keratometer reading provide the following information to assist in the overall assessment of the cornea:-\n\n\nRadii of curvature of the cornea\nThe degree of corneal astigmatism\nThe direction of the principal meridians of the eye, determining whether the astigmatism is with the rule or against the rule:- a key factor in contact lens fitting.\nThe presence of any corneal distortion.', 'role': 'assistant'}]