This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cornea and sclera, Subject name: Ophthalmology
[{'content': 'Snow blindness is caused by - \nSelect and explain. \nA. Ultravoilet rays, B. Infrarads, C. Microwaves, D. Defect in mirror', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Photophthalmia refers to occurrence of multipleepithelial erosions due to exposure to ultraviolet rayshaving a wavelength of 290-311 mm. It occurs in thefollowing conditions:1. Exposure to naked arc light as in industrial weldingand cinema operators2. Exposure to bright light of a sho circuit3. Snow blindness due to reflected ultraviolet raysfrom the snow surface REF:Comprehensive ophthalmology,AK Khurana,4th edition,pg no.507.', 'role': 'assistant'}]