Hi. I'm online and happy to answer your question today.
You discussed a number of issues in your post but I would like to address the most serious issue: The issue where you vision fades to black like a camera aperture closing.
It sounds like what you are suffering from is something called Amaurosis fugax (AF).
Amaurosis fugax is the transient loss of vision in one eye. It has many causes and, in the early 1990's, a study called the Amaurosis Fugax Study Group defined and grouped them to help with diagnosis and treatment of this problem.
What can cause AF? It can be due to an embolism, problems with the blood, problems with the eye itself or, sometimes due to no cause we can figure out (idiopathic). I would be happy to go through all the different diagnostic possibilities in each of these categories but I don't think that is the best use of your time.....you need to know what to do.
AF is a symptom that something serious is wrong. It can be a warning that you are heading toward a dangerous vascular event such as a TIA, stroke or even death. It is important for you to see your ophthalmologist and possibly your internal medicine physician ASAP. What will they do? A complete history and physical, a complete eye examination, maybe a fluorescein angiogram of your retina, laboratory tests, possibly ultrasound of your carotid arteries or an CT/MRI of your head.
Treatment depends on what is found on the above workup.
I can not stress enough the need for you to be seen for a complete exam as soon as possible.
Does this make sense to you?
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Let me know if you have further questions.
I see that you are offline. I'll switch over to the Q&A system. This system works a lot like 'text messaging' but an email is sent to each of us anytime something is posted to this thread. We can continue to work on your question there..... :)