My prescription is OD sphere > minus 6.0 , cycl > minus 1.75 and axis 5
and OS > minus 6.25, cycl > minus 1.25 and axis 180 . Can I get away with this mask without custom prescription for astigmatism? Thanks in advance.
I have a mild astigmatism but much stronger correction. I just got the basic lenses as close to my prescription as I could and they have been great.
I'm not an eye care professional, but I would suggest getting the strongest corrective power lens they have. Looking underwater has a minor corrective/refractive affect anyway. I think what you will find is that its not perfect, but it will be so much better than you've ever been able to see underwater that it will be great.... at least that's what my experience has been. My prescription is only around -3.5, and I think I got the -3.0 lenses. As silly as it would look, I could get around just fine, and even drive with them on.
These lenses were actually for my wife but she said she had no problems & could see fine, in addition I also purchased prescription masks from a different source online and those did not correct for astigmatism either and they worked out fine for me, I dove Palau & Truk Lagoon and vision was not an issue at all, everything was crystal clear... The way things appear underwater is very diffent from what they look like out of the water, astigmatism correction is not vital for underwater vision...
You would be best to ask your eye doctor. During your next exam, he can show you what the standard prescription would look like. Then you can decide. Since you won't be doing much reading while diving, it may not matter. I have astigmatism too, but I'm just using the closest weaker prescription insert. With the magnification from the water, it hasn't been a problem.
By coincidence, I am an ophthalmologist. You can "get away" with a minus 6.50 in your right and left eye. But given the significant amount of astigmatism you have, your vision underwater with the TUSA sphere only lenses will not be as sharp as with a custom prescription that fully corrects your astigmatism. Also, if you are older than 45 consider under correcting your full myopia by a little bit, or putting a bifocal in one lens(on the side you keep your gauges/computer on) because of presbyopia (decreased focusing ability at near as we all get older) after that age
I don't remember my exact Rx but I too have an astigmatism and I don't have any problem with the stock lens. However, your Rx is much stronger that mine. I also added some dive optics to enable me to read my guages.