While functional vision loss can certainly be suspected on routine exam based on the patient's response to visual and ophthalmologic testing, it is still a diagnosis of exclusion. However, we are not advocating that every suspected patient undergo the full battery of ancillary tests, as certain tests and procedures may be tedious, inconvenient, and excessive (particularly radiological imaging and electrophysiological tests). Since functional vision loss encompasses a wide variety of conditions, diagnosing cases of the condition should be varied accordingly. Depending on the particular circumstances with the patient, it is up to the individual practitioner to decide how far to pursue ancillary testing to feel comfortable with the diagnosis.