It’s usually difficult to implicate a drug and prove the cause effect relation. One has to rule out all other causes of the adverse effect.
It’s important in this case to do the MRI brain/ orbit to r/o sheath infiltration as the blood vessels pass through it.Ischemic CRVO is usually associated with RAPD, disc oedema hence the optic nerve involvement may be masked
Typically a drug induced vasculitis will affect the other eye too. The FFA/OCT may pick up the other eye changes if the findings are subtle.
CRVO can be associated with significant macular oedema and haemorrhages which can settle over a period of time and may need intravitreal antivegf injections. It may be too early to call the patient one eyed just yet.
If there’s any evidence of a threat to the other eye on retina work up or autoimmune serology then we may consider intravenous steroids.