If you haven't tried this it works pretty well. Invoke Siri on your iPhone. You can use the home button, or say "Hey Siri" or whatever method you might use to start Siri. Then just say "Make Eye Doctor Appointment for 10 AM on August 3rd". Siri will make the appointment and add it to your calendar.
In the example below, that's exactly what I did to have Siri create this appointment for my Eye Doctor. I said "Hey Siri, schedule my eye doctor appointment with Dr. Wilson at 10 AM on Aug 3rd" and Siri scheduled this appointment.
