My Wife Has Ocular Histoplasmosis And Has Been Receiving Ocular

My wife has ocular histoplasmosis and has been receiving ocular injections monthly for the past 3.5 years (Avastin, Lucentis, and now Eylea). Her ophthalmologist is recommending advancing to PDT with Visudyne. We've read of the procedure and are concerned about possible permanent loss of vision if the procedure does not go well. Her vision in the affected eye is still good (20/30). Any advice? Thanks.