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
Snow blindness is caused by - 
Select and explain. 
A. Ultravoilet rays, B. Infrarads, C. Microwaves, D. Defect in mirror
A: Ultravoilet rays
Answer: A: Ultravoilet rays 
Explanation: 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.