There were cases of blindness with intranasal steroid injection in the past. The circumstances around these event are still a bit fishy.
Mabry did THOUSANDS of such injections without a problem. He published an article with his advice for injections in the past.
Essentially pretreat the nose with a decongestant, slow injection after pulling back on needle.
I would not fear an injection.

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Steven M. Houser, MD
rhinology, allergy, and sinus disease