Hi Db,
I had similar sudden event behind & into eyeballs, popping sensation & pressure into eyeballs but also some temporary shrinkage of the size of the eyeballs.
I was on a lot of B12 sub-lingual at the time plus 2 weeks on Gabapentin 100 mg. Pretty much have had Dry Eye ever since, & am missing Lipid Layer of tear film. Pressures were surprisingly on low side of normal (10 and still are).
I also got the best help from my 2 local Optometrists, who recommended Fish Oil 3000mg/day. Takes a month or so to start helping the Dry Eye. It does help b/c I notice if I stop. I've reduced to 1000mg/day now. Seems enough.
I have since been to two Opthalmologists (Medical specialists) and a 1 min consult with a Neuro Opthalmologist...All these had no explanation of my sudden eye event. My eyes tested normal except for the Dry Eye,
It all leads me to think it was some Glaucoma-type event, perhaps toxic & or inflammatory, from too much B12 building up in my system (shown on blood tests) plus Gabapentin. I straight away reduced my B12 & stopped Gabapentin. I now no longer tolerate any dose of supplemental B12.
The above explanation, is perhaps combined with fragile eyes due to the Connective Tissue Disorder that other Drs & I have concluded I probably have eg Ehlers-Danlos Syndrome. The plot thickens

...the investigations are ongoing...sigh...
Meanwhile I'm re-introducing the supplements that support fragile connective tissue mentioned here:
http://forums.phoenixrising.me/inde...rome-stretchy-veins.20351/page-24#post-340216
http://en.wikipedia.org/wiki/Glaucoma I notice there are a lot of possible causes of the sudden painful event type of Glaucoma.
23andMe put me at higher risk for Exfoliation Glaucoma.