Blurry vision underwater is due to pupil dilation, which can be controlled to see as if wearing mask

[wKkaY]

LASIK vision correction does not, in ANY way affect dark adaption, it may however result in issues in low light conditions for various reasons including but not limited to residual corneal haze, epithelial defects, and dry eye symptoms which are usually worse at the end of the day.

In my case it's mainly due to the PRK treatment optical zone (6mm) being smaller than my dark-adapted pupil size (7mm).

 

[DavBuc]

Actually, yes there is:
"...
Blended ("Invisible") Bifocal
Although most bifocals and trifocals have visible lines at the border of lens segments, there is a blended round-seg bifocal that has a less noticeable near segment than its regular round-seg cousin. The near seg is blended into the distance portion of the lens so that it is virtually invisible..."
Bifocals and Trifocals for Vision Over 40

SeaRat

There is no such thing as a blended invisible trifocal. As I posted earlier, it does not exist.

You quote me and say I'm wrong and then you post about blended invisible bifocals.

Trifocals and bifocals are not the same thing.

 

[DavBuc]

In my case it's mainly due to the PRK treatment optical zone (6mm) being smaller than my dark-adapted pupil size (7mm).

That's a separate issue that has nothing to do with dark adaption, it has to do with blur and distortion because when there is less ambient light, the pupil becomes larger than the zone that was treated by the refractive surgery.

 

[gcarter]

That's a separate issue that has nothing to do with dark adaption, it has to do with blur and distortion because when there is less ambient light, the pupil becomes larger than the zone that was treated by the refractive surgery.

Which means that low light vision is affected by laser correction.

Regardless of how you want to colour it.

 

[John C. Ratliff]

There is no such thing as a blended invisible trifocal. As I posted earlier, it does not exist.

You quote me and say I'm wrong and then you post about blended invisible bifocals.

Trifocals and bifocals are not the same thing.

You, Sir, did not read the whole page link. There, the thread refers to both bi- and tri-focal as blended, with illustrations. They are called "Progressives," but my optometrist also called them "blended trifocals."

lended bifocals should not be confused with progressive lenses, which are special no-line multifocals that incorporate all corrections, from distance to close-up, into one lens without any separation of the various visual zones by lines. Today, more people prefer progressive lenses over bifocals or trifocals, partly because they provide a younger appearance with no age-revealing seg lines.

Now, for those of us who do want excellent underwater near-vision, I would recommend picking up a pair of SeawiscopeEY lenses, and attach them to your mask. These are made by an optometrist from Hong Kong, and these really work, allowing 3D very close (macro) vision of underwater life (see my avitar for an example). I have used them to observe insect larva, sponge and other very small freshwater life. I once watched a hydra about the size of my thumbnail for five minutes as it, while attached to a leaf, captured time life from the Clackamas River.

Now, about kids becoming more able to focus and see underwater without a mask or goggles, I do not believe it. The reason is my personal experience. I grew up in the 1950s and early 1960s on swim teams. We had no goggles, but we swam for an hour in our swim team practices with only our open eyes. I do not remember my eyes adjusting to the underwater blur, even when we had extended, intensive practices. I do remember vividly what the chlorine in the water did to our eyes though. If it was bright when we came out, we would have rainbow halos around the bright lights!

SeaRat

PS, DavBuc, have you given any thought to changing your avitar? The one you've chosen does not enhance your credibility.

 

[lowviz]

...//... Now, about kids becoming more able to focus and see underwater without a mask or goggles, I do not believe it. ...

I think that the key phrase is "see better". How much better is the buzz kill.

In "1. Introduction" of this journal article (Visual training improves underwater vision in children - ScienceDirect), I read it as a doubling of visual acuity. That isn't much. However, the effect is well substantiated.

Doubling my acuity without a mask is "meh" but the physiology is fascinating. Nothing other than the small training effect is new here. Nice little nugget that I credit to the OP.

no mask/ read gauges?

 

[tridacna]

You, Sir, did not read the whole page link. There, the thread refers to both bi- and tri-focal as blended, with illustrations. They are called "Progressives," but my optometrist also called them "blended trifocals."


Now, for those of us who do want excellent underwater near-vision, I would recommend picking up a pair of SeawiscopeEY lenses, and attach them to your mask. These are made by an optometrist from Hong Kong, and these really work, allowing 3D very close (macro) vision of underwater life (see my avitar for an example). I have used them to observe insect larva, sponge and other very small freshwater life. I once watched a hydra about the size of my thumbnail for five minutes as it, while attached to a leaf, captured time life from the Clackamas River.

Now, about kids becoming more able to focus and see underwater without a mask or goggles, I do not believe it. The reason is my personal experience. I grew up in the 1950s and early 1960s on swim teams. We had no goggles, but we swam for an hour in our swim team practices with only our open eyes. I do not remember my eyes adjusting to the underwater blur, even when we had extended, intensive practices. I do remember vividly what the chlorine in the water did to our eyes though. If it was bright when we came out, we would have rainbow halos around the bright lights!

SeaRat

PS, DavBuc, have you given any thought to changing your avitar? The one you've chosen does not enhance your credibility.

You, Sir, did not read the whole page link. There, the thread refers to both bi- and tri-focal as blended, with illustrations. They are called "Progressives," but my optometrist also called them "blended trifocals."


Now, for those of us who do want excellent underwater near-vision, I would recommend picking up a pair of SeawiscopeEY lenses, and attach them to your mask. These are made by an optometrist from Hong Kong, and these really work, allowing 3D very close (macro) vision of underwater life (see my avitar for an example). I have used them to observe insect larva, sponge and other very small freshwater life. I once watched a hydra about the size of my thumbnail for five minutes as it, while attached to a leaf, captured time life from the Clackamas River.

Now, about kids becoming more able to focus and see underwater without a mask or goggles, I do not believe it. The reason is my personal experience. I grew up in the 1950s and early 1960s on swim teams. We had no goggles, but we swam for an hour in our swim team practices with only our open eyes. I do not remember my eyes adjusting to the underwater blur, even when we had extended, intensive practices. I do remember vividly what the chlorine in the water did to our eyes though. If it was bright when we came out, we would have rainbow halos around the bright lights!

SeaRat

PS, DavBuc, have you given any thought to changing your avitar? The one you've chosen does not enhance your credibility.

John,

I tried those. Almost impossible to attach properly to one’s mask. Silly pieces of string supporting a heavy frame. After much struggling, I was able to do so but was underwhelmed by results.

I just use built-in readers these days. That entire episode cost me $200. They’re impossible to resell after purchase. I’m glad they work for you.

 

[DavBuc]

You, Sir, did not read the whole page link. There, the thread refers to both bi- and tri-focal as blended, with illustrations. They are called "Progressives," but my optometrist also called them "blended trifocals."

You sir, are confusing bifocals with trifocals with progressive multifocals.

They are three distinct and different entities.

As the prefix "bi" indicates, a bifocal has 2 distinct lens areas, a "tri" focal has 3 distinct lens areas and a "multi" focal has an infinite number of focal points- it can be thought of as a sort of "ramp of ever changing lens power".

Your optometrist may use the term trifocal to describe a progressive multifocal to simplify things when describing them but it is not correct.

I maintain that while there are such thing as a 'blended bifocal' there is no such thing as a blended trifocal or even a blended multifocal, which is what I posted originally.

 

[DavBuc]

Which means that low light vision is affected by laser correction.

Regardless of how you want to colour it.

You are confusing "poor vision in low light" with "dark adaptation" which are not the same thing.

Don't believe me? Google it.

 

[gcarter]

You are confusing "poor vision in low light" with "dark adaptation" which are not the same thing.

Don't believe me? Google it.

I confuse nothing.

Measure of effective low light vision before laser correction = x

Measure of effective low light vision after laser correction = x - y with no other changes being made.

Conclusion: low light vision is reduced after laser correction.

You can explain the mechanism for this however you want; it does not change the fact theat they are linked, and a very high number of people - myself included - report reduced low light vision after laser correction.