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JugglingMonkeys
08-18-2007, 10:13
I have glasses with a very strong prescription.

But when i'm underwater with a mask I see perfectly.

should I NOT get a prescription mask then?
i assume my better sight is due to the magnifying effect of the water?

NitroWill
08-18-2007, 10:20
If you can see perfectly then theres no point in them! The water could very well be helping you see better :smiley20:

PlatypusMan
08-18-2007, 10:41
I have glasses with a very strong prescription.

But when i'm underwater with a mask I see perfectly.

should I NOT get a prescription mask then?
i assume my better sight is due to the magnifying effect of the water?

What is happening is due to the refractive index of water--put simply, light is 'bent' as it travels through a solid medium other than a vacuum to a greater or lesser degree depending on what medium it is. You can see this effect when you take a glass of water and put a straw or pencil in it and look at it through the side of the glass; you will see that as the object enters the water-filled portion of the glass, it appears to 'bend', even though you know that it's perfectly straight.

I too, have noted over the years that a mask while in water gives reasonably clear vision (in fact this is the effect that the makers of the Hydrooptix mask depend on for their product)--but what do you do while on the surface? Can you make out the boat? Your dive buddy? Someone in distress?

A prescription mask will help you in those situations.

DivingsInMyBlood
08-18-2007, 10:55
I have a prescription mask (im short sighted i use -2 lenses) these things are awsome and i can see so crisp and clear below and above the water whilst wearing these.

JugglingMonkeys
08-19-2007, 10:06
but what do you do while on the surface? Can you make out the boat? Your dive buddy? Someone in distress?

A prescription mask will help you in those situations.

good point!

will a prescription mask hinder the underwater vision at all?
I'd hate to wreck it now that i can finally see!

ScaredSilly
08-22-2007, 10:08
On the surface I always wear my Rx mask so I can see. It does not come off until my gear is off or I at least sit down. Even wear on the boat at times. Yeah people think I am dork (my wife would say I am anyways) but I want to be able to see.

Go to a store that has a mask that have drop in Rx lenses in std. dioplers and try one out in the pool. These are basic lenses that work well - I use them in one mask. Try your mask and rx mask and see what you think. I bet the Rx will be even better. The drop in lenses are a nice compromise to the cost of a full Rx mask. That said my Atomic Split Frame mask and the drop in did not work and I had to go to a full Rx.

peteg
09-15-2007, 10:35
FWIW, i have -2.75 and astigmatism in both eyes. Underwater, with a regular mask I can see pretty well, and did many a dive like that. Then I did a boat dive and the shop offered me a -3 mask to try out. Wow! I had no idea what I was missing, so I bought a new mask and -3 inserts. It's not a perfect prescription above water because the lenses don't correct for my astigmatism, but the slight overcorrection helps. Underwater it's very nice because the magnifcation factor of the water nearly negates my astigmatism.

CompuDude
09-16-2007, 13:14
I agree. Prescription masks are great. I have had custom and the cheaper drop-in lenses, and both are good. Custom is a lot clearer on the surface, while underwater, the drop in lenses seem to work just fine. Either way, having the prescription mask allows me to see a lot better than nothing when I'm topside, so yes, I also usually keep my mask on until I get back to where my glasses are so I don't have to be blind so long.

ScubaToys Larry
09-16-2007, 13:22
We do custom prescriptions all the time... through SeaVision, and we have multiple masks that take drop ins.

Here's the rule of thumb that seems to work for most... When looking at your prescription... there are 3 boxes. Should like about like this:

OD -2.5 1.25 90
OS -3.0 .60 40

OD = oculus dexter = right eye;
OS = oculus sinister = left eye.

The first is the diopter you would need... in this case -2.5. The next two numbers are for your astigmatism. What we have found is if the second (middle) number is 1 or greater, you will probably be happiest if you get them custom ground. If it's something like .25 or .60 then the drop in ones would probably be good enough for you.

Hope that helps!

jpep
09-16-2007, 15:27
As someone who had been nearsighted for years, one of the best gifts I ever received was a gift certificate for a prescription mask... finally was able to realize what I was missing u/w!

Drop in lenses will generally compensate for nearsightedness (myopia) even with an astygmatism, as they come in standard 1/2 diopter strength graduations. After trying/testing split lens masks that fit for sizing/comfort, just bring your correction prescription into a dive shop that sells drop in lenses and you should be good to go. Generally it is preferrable to not overcompensate lens strength, given the difference between the refractive properties of air and water.

The fun starts as you age and also develop farsightedness (hyperopia) and run out of arm length... coupled with the attendant limitations of hose length in reading your gauges. :smiley2: But that's whole 'nother kettle of fish!

Capt Hook
09-16-2007, 16:37
Prescription mask is definitely the way to go, you may see better underwater with regular lens but the difference using RX lenses is amazing.

Bill22
09-18-2007, 11:29
Depending on how "blind" you are a prescription mask can be really helpful for all the reasons stated above. I loved my prescription mask (I was 20/200). Don't need it now that I've had PRK (I'm 20/10 now), but at the time it really was the way to go :-)