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': 'Soft contact lens is made up of \nSelect and explain. \nA. PMMA, B. HEMA, C. Glass, D. Silicone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. HEMA Types of Contact Lens Hard Gas permeable (Rigid or semisoft) Soft Made of PMMA (poly methyl metha acrylate) Q Copolymer of PMMA, silicon containing vinyl monomer and cellulose acetate butyrate (CAB) HEMA (hydro? xy methyl metha acrylate) Q Oxygen delivery Poor Moderate to high High Deposits Few Few More Visual clarity Good Clear Need to refocus after a blink Use in astigmatism Possible Possible Less suitable Adaptation Required Required Not required Durability May scratch Do not scratch or tear Tear', 'role': 'assistant'}]