Microbiology All India exam 3f6790c7 Most common cause of ophthalmia neonatorum is A Chlamydia B Gonorrhoea C HSV D Staph aureus High-Yield Explanation Chlamydia is the most common cause and presents by 4-10 days. Ref: Ananthanarayana textbook of Microbiology 9th edition Pgno : 419