I am sorry you are dealing with this. Based on current research, there is no evidence that psilocybin or LSD can restore major vision loss that started after venlafaxine. Cases like this are rare and unstudied, so I cannot verify any claim of benefit.
A psychedelic session might indirectly help if stress or functional mechanisms maintain the symptoms, through relaxation and cognitive shifts, but this is speculative and not proven to recover sight. For background on neuroplasticity and psychedelics, see this overview.
Before considering psychedelics, please make sure an ophthalmologist or neuro ophthalmologist has thoroughly evaluated you. There are rare reports of eye pressure problems with venlafaxine that can affect vision; I cannot assess your risk here, so exclusion by a specialist is important.
If you still wish to try, set modest expectations, track symptoms, and prioritize safety and integration. I hope this helps.