Table 5. Diagnostic modalities and their role in diseases of the visual system.

	Migraine	Epilepsy	Ischemia	VSS	HPPD	CBS
cMRI	–	Mandatory	Mandatory, with ‧vi‧sualization of vessels	Single scan ‧indicated	Single scan ‧indicated	Single scan ‧indicated
EEG	DbA	Indicated	–	?	DbA	DbA
VEP	–	–	–	?	DbA	–
Sight testing	–	–	In CRAO	Indicated	Indicated	Indicated
Perimetry	Indicated at first occurrence and in presence of persistent symptoms; homonymous defect during aura	–	In CRAO	DbA	DbA	Indicated
Funduscopy	–	–	In CRAO		DbA	Indicated
Treatment	Specific treatment rarely necessary; migraine prophylaxis if indicated	Multiple	Systemic lysis in acute phase, otherwise secondary prevention	Explanation; trial of lamotrigine if indicated	In some cases ‧anticonvulsants, benzodiazepines, and neuroleptics	Explanation; ‧anticonvulsants and neuroleptics if ‧indicated
Specialty	Neurology	Neurology	Neurology,ophthalmology	Neurology	Psychiatry	Ophthalmology

CBS, Charles Bonnet syndrome; cMRI, cranial magnetic resonance imaging; CRAO, central retinal artery occlusion; DbA, diagnosis by exclusion; EEG, electroencephalography; HPPD, hallucinogen persisting perception disorder; VEP, visual evoked potential; VSS, visual snow syndrome; –, not indicated; ?, role unclear