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Your retinal specialist will be the best person to ask about this -- because they will be looking at the back of your eye and understand how serious this retinal vein occlusion is -- and because you are scheduled for an injection, I have to assume you have significant vein occlusion.
The injection that is scheduled is a medication that helps to promote blood vessel growth, to help with the blood drainage from the retina -- and it is clearly shown to help, with very strong medical evidence to show that it works.
While homeopathic treatments may not hurt, they have not been shown to help like the injection -- and so I would not risk your vision by foregoing the injection for homeopathic medication.
You probably can ask your retina specialist if you can try those homeopathic supplements while you receive the injection (it is probably OK, but ask for their opinion first).