Progressive lens dive mask?

[JoeTPhilly]

Reading and distance contacts?

Yes, there are contacts that correct for both. I use Bausch + Lomb Bio True for Presbyopia. They are daily wear and work well.

 

[sea_ledford]

I've been using bifocal mask lenses for 10 years or so. Just ordered my first trifocal for video use since my monitor sits right between the near vision and far vision focus distances. I've gotten 4 masks from Leonard Maggiore (Leonard Maggiore Opticians | Providing Perfect Vision, Since 1936).

I have a strong astigmatism so contacts and the off the shelf prescriptions don't work for me.

I'll have to look into the SeaVision option next time if they offer true progressives.

 

[TNEngineer]

just because you have progressives above the water does not rule out bifocals below. Prescription Dive Mask did my full prescription. It is a bifocal and it works great underwater.

I too have progressives above, Prescription Dive Masks (PDM) bifocals below, and both work very well. PDM talked me into raising the dividing line (increasing the height of the near vision region at the bottom) and I wish I'd gone with my original estimate because I don't need that large an area for near vision. That's one of the reasons I'm interested in underwater progressives... they might allow ME to move that line around by tilting my head, just like progressives do above water.

I have an optometrist appointment coming up, and if my correction has changed again (as I suspect) I may be updating all of my optics which will give me a chance to refresh my dive mask choice.

 

[TNEngineer]

Lots of people get cataract surgery much earlier than necessary because the replacement lenses correct their refractive error so they no longer need glasses for distance

It's my understanding that the artificial lenses have even less focal range than older, hardening natural lenses for most of your life. I've been pretty nearsighted since 5th grade but have avoided laser surgery on my corneas because all that does is shift your focal point - it doesn't increase focus range, which naturally reduces with age as your natural lenses harden.

I have incredibly sharp vision, just biased near, and given my Engineering profession I'd much rather have unassisted sharp close vision than far.

My biggest problem now is floaters. I have one in my right eye that is directly over my fovea (focal point) 99% of the time. Unbelievably annoying. I'm developing a subconscious eye shift thing because it moves the floater out of the way for a few seconds. But my research into dealing with floaters isn't very reassuring... lasing them has mixed reviews, and I really REALLY don't like the "drain the vitreous humor and just leave air in your eyeball" approach.

 

[TNEngineer]

You're going to the wrong optometrist.

I wore contacts for decades, but as my lenses hardened with age and multifocals became necessary I was told by multiple optometrists that multifocal contacts are not an option if you have any degree of astigmatism. I haven't worked through the details of "why" but if that's not true it's a broadly held misbelief by a lot of people in the medical community.

 

[TNEngineer]

Not quite. Until recently, replacement lenses had no ability to change focus, but there are new types that actually accommodate just like the human eye, they are placed within the original sac that the natural lens was located and the zonules that pull on the sac can focus the replacement lens just like the original lens.

Hooray! I've finally found someone else who knows about the Zonules of Zinn! I use that as a trivia question and I've never, ever found anyone outside the optical profession who knows what the heck I'm talking about.

I'm cheered to learn that replacement lenses have better compliance now. My understanding was that they had some, but it was marginal, forcing even more external correction to have any sort of focal range.

Vitreal floaters increase with age, there's no way around it but you don't need a complete vitrectomy to remove them. Air isn't left in the eye, the vitreous is replaced by a gel. Anyway, there are new, much less invasive procedures to remove floaters but they are usually only done when the floaters cause major vision problems. You can probably find an Ophthalmologist who will find a medical need to have the procedure covered by insurance.

That's part of why I have the upcoming appointment - to see what the options are. I'm conservative when it comes to my eyes... I only get two of them and I'd rather accommodate poorer vision than have "something go wrong". For example, I never used "leave-in" contacts nor disposables... I used long-term lenses and religiously cleaned them every single night.

Man, I loved contacts. Like perfect vision. No parallax as with glasses, razor sharpness, etc.

Are all of these optometrists that tell you that you can't wear contacts doing their exams in a storefront location as compared to private practice? Working a theory here.

No, I don't use "storefront doctors" of any kind. These have all been private practicioners, including one who is a family friend (our wives worked together back in the day). He's actually the last one to prescribe contacts for me, taking me from the hard (non-gas permeable) lenses I had grown up with to gas-perms. Not quite as razor sharp as hard plastics but apparently healthier for the corneas, allowing them more oxygen uptake.

 

[TNEngineer]

You appear to be confusing two different things here. Depth of focus is more a function of pupil size than anything else... Accommodation is the change in refractive power of the intraocular lens due to its shape

I understand the difference. In this discussion I'm speaking of the dynamic range of focus - the range of nearest to farthest objects your viewing system (eyes plus appliances) can bring into focus.

You can think of that range in two ways. First, you can simply think of the "nearest" and "farthest" possible focus distances. Alternatively, you can think of (farthest minus nearest) as the dynamic range, and the median of those two distances as the "center" of the focus range.

As our lenses harden at 40YO+, one effect is that center moves more distant. This is why most people start requiring "readers" for near vision. For those of us with myopia, our required correction actually reduces. I used to be nearly -5.00 diopters and lately I'm in the low -4.00's. Gets lower every couple of years.

The sad part is the second effect: The lens hardening also makes it more difficult for your eye muscles to reshape the lens, resulting in an overall narrowing of that dynamic range. Said differently, the "nearest" and "farthest" get closer together. This is why most people end up with bi/trifocals or progressives.

Think of them as a transmission for your lenses... they normalize the narrowing (focus or RPM) range of one system (eyes or engine) to the wider range required by the outside world (vision or wheels). Bi/tri's are like a manual transmission, with discrete ratios. Progressives are like a CVT!

It is this second part that means I'll never be without corrective lenses of some type. My prescription is "getting more normal" but I'm losing range, just like everyone else does at 40YO+.

 

[TNEngineer]

Think of them as a transmission for your lenses... they normalize the narrowing (focus or RPM) range of one system (eyes or engine) to the wider range required by the outside world (vision or wheels). Bi/tri's are like a manual transmission, with discrete ratios. Progressives are like a CVT!

No offense but I prefer not to think of it that way, it's way too confusing and not really all that relevant.

Analogies are often helpful when discussing technical topics. Virtually everyone has experience with transmissions, which are a tool for normalizing one dynamic range to another. That's precisely what is happening here with our eyes and bi/tri/progs. I now know that you are in the profession and so have a deeper understanding, but perhaps the analogy will help others as they scan this thread.

 

[Ontwreckdiver]

Reading and distance contacts?

Yes, but I still have different prescriptions for each eye. The one in my left eye is geared towards reading and the right one is towards distance

 

[BoltSnap]

Yes, but I still have different prescriptions for each eye. The one in my left eye is geared towards reading and the right one is towards distance

Can you have both for the same eye, reading & distance, or is it one or the other?