Decreasing clarity of vision with depth

[Rick Inman]

I am near sited and wear soft contacts while diving. On the surface, the contacts correct my nearsightedness, but cause me to need reading glasses for closeup (ah, the joys of aging...). So, I wear bifocal contacts for diving only, which are great for helping me to see my gages. Here's the question:
As I descend below 50 feet, my close up vision tends to blur a bit, making it more difficult to read my computer clearly. The deeper I descend, the more the blurriness. At 100 feet, it is very difficult to read my computer (but possible). I blink and squint (the normal stuff) to no avail.
Is this normal? What would cause this to happen? Will my buddies laugh at me if I use a big magnifying glass at depth?

 

[ArcticDiver]

Say how do those bifocal contacts work out for you? I've thought of them but haven't met a diver yet who used them.

To your question: I certainly don't have any answers. But the obvious thing is the combination the water's magnifying effect and some pressure distortion of the lense. But, I'm sure you already thought of those.

As for laughter......Hmmmm......How Big A Glass?

 

[pipedope]

Have you tried using a dive light to read the gages?

Have you contacted your eye doctor?

 

[AevnsGrandpa]

I wonder if it may be related to the increase of pressure on the contacts, flattening them out, changing their focal distance....

Interesting.

Jeff

 

[Rick Inman]

Say how do those bifocal contacts work out for you? I've thought of them but haven't met a diver yet who used them.

The bifocal contacts work great! They only clear up distance vision to about 30 feet, but that's more than enough underwater. They take a little getting used to, but with then I can see close up without my glasses. An optometrist on this board recommended them.

Have you tried using a dive light to read the gages?

Sure. Blurry and lit up. No doc yet.

 

[H2Andy]

What would cause this to happen?

i wonder if under the increased pressure, your contact lenses
are being pushed closer to your pupil, thus becoming, in effect, a "stronger" prescription.

(the closer a lens is to your pupil, the better it works).

i used to have this problem (though not underwater) and
i got slightly LESS powerful contacts, and that worked a charm.

 

[Charlie99]

What you describe sounds like the same depth-of-focus problem some people have at night. Just like a wider aperture in a camera reduces your depth of focus, the wider pupils of your eye in low light levels results in a smaller depth of focus. So you can see well at whatever distance your corrective lenses or contacts are set up for, but if you are corrected at distance, then reading close up stuff is much more difficult.

This sort of difficulty is more common for us folk over 50 as the lens in our eyes gets less flexible and its focussing range decreases.

Charlie

 

[Rick Inman]

So you can see well at whatever distance your corrective lenses or contacts are set up for, but if you are corrected at distance, then reading close up stuff is much more difficult.

Yeah, but this is what the bi-focal contacts are supposed to take care of (interior of lens corrects for nearsightedness, outside of the lens works like reading glasses), and they do it just fine on the surface on shallow.

What you describe sounds like the same depth-of-focus problem some people have at night. Just like a wider aperture in a camera reduces your depth of focus, the wider pupils of your eye in low light levels results in a smaller depth of focus.

Ah ha! Yes, in fact I didn't notice the problem so much in the clear, bright waters of Hawaii last month. But here in the dark waters of the PNW, you get below 50' and it starts getting real dark. In fact, with the 8' of vis we've had the last few weeks (run off), it gets real dark real fast.
Interesting...

 

[ArcticDiver]

Yeah, but this is what the bi-focal contacts are supposed to take care of (interior of lens corrects for nearsightedness, outside of the lens works like reading glasses), and they do it just fine on the surface on shallow.


Ah ha! Yes, in fact I didn't notice the problem so much in the clear, bright waters of Hawaii last month. But here in the dark waters of the PNW, you get below 50' and it starts getting real dark. In fact, with the 8' of vis we've had the last few weeks (run off), it gets real dark real fast.
Interesting...

So, like I surmised you had already thought of the pressure induced differences.

But, I hadn't thought about the light thing either. Guess it is because I routinely use a light when diving up here. Sort of guessed you did too. That'll teach me to suppose!

 

[baitedstorm]

I am by far a doctor, but I've been in the optical field for 12 years, my suggestion would be to try a mono fit instead of the actual bi-focal contacts. My husband wears regular Acuvue lenses (he's nearsighted too) and has no troubles even at 100 feet. I can't see how the pressure would cause the Rx to change, seeing how contact lenses eliminate vertext distance (space between your eye and your Rx glasses). If it were me, I would call up th OD and ask to try the mono fit, certainly couldn't hurt....... hmmmm (ask him about depth perception with the mono fit and make sure he knows your diving)
Good luck