498
Retinal abnormalities, including retinal hemorrhage and "cotton-wool" spots, often occur within the first 8 weeks in the course of interferon therapy in patients with chronic hepatitis C.
 adverse event: occur 
Please tell me event type and its trigger word from given type options. Output format is "type: trigger".  Option: adverse event, potential therapeutic event 
Text: {0} 
Answer:
 adverse event: occur 