Here are some common situations that should be considered urgent:

• Sudden vision loss
• Severe eye pain
• Flashing lights or floaters
• Eye injury with foreign object
• Chemical splash in the eye
• Significant redness and swelling 

General first aid for eye emergencies (consult a doctor immediately):

• Do not rub your eye
• Cover the eye with a clean, loose eye shield or cup
• Do not apply pressure to the eye
• Rinse eye with cool water if appropriate (check with a healthcare professional)