Seeing black when descending

[MermaidLaura]

Yesterday I did a dive down to 17m. This was my first dive of the day (and first dive in 10 days) I was not stressed, I was relaxed, and when I was descending (breathing regularly), I suddenly got black blobs in front of my eyes at about 10m (I'm guessing 10m) Not really blobs, it was like rectangular blocks across the bottom half of my eyes for a few milliseconds. Wierd. I was concerned I might be getting narced so I stopped a few seconds and they disappeared. I carried on diving and everything else was fine.

Does anyone have any idea what this could have been? I have never had this before (I've done over 500 dives).

It would be interesting to have some input.

Thank you!

 

[Duke Dive Medicine]

Laura,

Did you feel any sinus congestion, perhaps from a cold or allergies? The optic nerve runs right next to the sphenoid sinus, and in 15-25% of the population, the bone between the sinus and the optic nerve is missing. There are a number of case reports of people experiencing pressure-related blindness on ascent to altitude; you would be the second diver I've heard of this happening to. I would very much like to correspond with you about this. If wouldn't mind, can you send me a PM with your email address?

Best regards,
DDM

 

[MermaidLaura]

Hi

Nope, nothing, no sinus, cold or allergies.

That's what has me so dumbfounded and I don't want it to happen again!

I'll pm you

 

[DevonDiver]

If I 'press' on my eyeballs I get a similar sensation. Possible that you weren't quite equalizing your mask quickly enough - causing slight over-pressure which led to the visual disturbances?

(I'm not a Doc)

 

[MermaidLaura]

No idea....

Dived again this weekend and nothing happened. Maybe a slight sinus squeeze or over pressure...

Thanks guys!

 

[Hatul]

If I 'press' on my eyeballs I get a similar sensation. Possible that you weren't quite equalizing your mask quickly enough - causing slight over-pressure which led to the visual disturbances?

(I'm not a Doc)

Hi Andy, On descent that would cause a relative vacuum inside the mask (under-pressure). Even so the mask squeeze could possibly be the explanation as it would pull on the eye and possibly stretch the optic nerve.