As mentioned the fluorescein angiogram basically shows changes MUCH MUCH earlier than what is “visibly” seen in a slit lamp exam… by the time you can “see” changes, it’s no longer early, and is in fact fairly advanced. I had a full dilated eye exam last April after a sudden loss in my visual field, and was diagnosed with a BRVO but no visible “diabetic changes” and referred to a retina specialist to investigate the BRVA. A fluorescein angiogram confirmed I did indeed have a BRVO and showed that I also have several micro-aneurisms in one eye - which means I was officially diagnosed with the earliest stages of retinopathy because it had to be accurately charted that way. The BRVO resolved on it’s own in just a few weeks (I was recovering from severe anemia and had very elevated platelets at the time, and my doc suspects that contributed to a small blood clot forming and causing the blockage in one of those super tiny vessels) before we had to discuss any kind of intervention (which is, ironically enough, would have been the exact same injections they use to treat retinopathy - it stops the development of new fragile blood vessels, which is effectively what retinopathy is - if the BRVO had remained long enough, there’s a risk that the body working to try to “fix” things will start to create new circulation).
Now, my retina specialist reassured me REPEATEDLY that what he was seeing was not exactly unexpected after 15 years with T1D, but actually not at a stage when most people were diagnosed (because it’s usually much more advanced - he was actually almost excited when telling me all of this - I got the impression I was not at all like their typical patient), and really not any cause for concern at this time as long as I maintained good control (I do) and that at this stage the ONLY thing we need to do is keep a close watch out for any future changes, and of course to call ASAP if I noticed any sudden changes in my vision.