Update

I haven’t posted for a while but I found this Wikipedia page (I have no clue why I’ve never come across it before) that describes perfectly the symptom I have had since I was a teenager (perhaps 14 or 15 years old). 

http://en.wikipedia.org/wiki/Visual_snow

I don’t remember whether I suddenly noticed this, or whether it appeared one eye at a time or in both eyes at the same time. I do remember that shortly after this first appeared, I experienced a complete distortion of vision, which only lasted a few hours. again, I can’t remember whether that was in one or both eyes, but it scared me so much that I went straight to bed. When I woke up in the morning, my vision had returned (although still snowy, of course).

I didn’t really worry too much about my snowy vision until the onset of my other symptoms 17 months ago. These started with numbness on the left side of my body, which spread over the course of several days (eventually including parts of my right side too), and lasted for several weeks before the sensation returned to normal. In my case, by ‘numbness’ I mean loss of sensation in the skin. I always retained full movement and control of affected limbs, i.e. the structures underneath the skin were not affected. 

During the period of numbness, I also began to suffer some other symptoms; heart palpitations and chest pain, dizziness/light-headedness, shortly followed by the appearance of blind spots in my vision. 

The blind spots started in my left eye and over the space of several days also spread to my right eye. They are situated around my central vision, but not in my central vision. They are in difference places in each eye, and only a couple of them overlap so that they are noticeable with both eyes open (the others are compensated for by the other eye). 

When the blind spots appeared, the ‘snow’ in my vision also got worse, and my eyes began to have more ‘memory’. The visual symptoms have never improved since their onset (but according to my ophthalmologist their is some amount of variation between appointments in my visual field results), but the snow and visual memory are made more manageable by avoiding dimly-lit rooms where possible.

Other symptoms I have also noticed during the past couple of years are: severe lethargy mid-afternoon; an inability to understand instructions or ideas, as well as written information (this is made worse by the visual problems); an increase in forgetfulness. 

I have never received a diagnosis for my symptoms, and my ophthalmologist has hinted that I shouldn’t get my hopes up. Examinations of my eyes have never shown up any problems, and neither did the MRI or lumbar puncture that I had last year.

I am looking to meet people that have similar symptoms so that we can share ideas and experiences. My ophthalmologist and the neurologists I have seen struggle to make sense of the symptoms I am describing to them, so other sources of information would also be gratefully received.