How does a doctor know whether someone has a retinal detachment over the phone?

Symptoms: Careful questioning of the patients symptoms, asking about new floaters in the vision, whether or not flashes of light are seen, and if there is any loss of peripheral vision can give a doctor a reasonably good idea about whether there is a retinal detachment, or not. The only way to know for sure, though, is with a thorough dilated retinal examination.

Not really: The symptoms described over the phone such as flashing lights, floaters, and vision loss, and the patient's history may suggest the diagnosis, but the only way to know is to get a dilated examination.