Buadhai
Contributor
I started wearing reading glasses about 15 years ago. About a decade ago I started having trouble seeing my dive computer, so I bought some Optix stick-on reading lenses. I positioned these at the bottom of my mask lenses and was pleased with the result: they stay affixed and enable me to easily read my computer and gauges.
On one dive I accidentally noticed that the positive diopter (+1.5) lenses improved my underwater visions at all distances; a meter, ten meters, infinity.
So, I moved the Optix lenses to the middle of my mask and now enjoy vastly improved vision while diving.
But, this does not work at the surface. With my reading glasses my vision is good only to a meter or so.
I'm sure there is an optical explanation for this, but I don't get it. How does water's higher-than-air index of refraction make it necessary for me to wear positive diopter lenses to see clearly under water at all distances?
Anyone else out there notice this?
(I should note that I recently had an eye exam with a opthamologist. My distance vision is just better than 20/20, an improvement from 20/40 for most of my life. I stopped wearing glasses for distance vision about five years ago.)
On one dive I accidentally noticed that the positive diopter (+1.5) lenses improved my underwater visions at all distances; a meter, ten meters, infinity.
So, I moved the Optix lenses to the middle of my mask and now enjoy vastly improved vision while diving.
But, this does not work at the surface. With my reading glasses my vision is good only to a meter or so.
I'm sure there is an optical explanation for this, but I don't get it. How does water's higher-than-air index of refraction make it necessary for me to wear positive diopter lenses to see clearly under water at all distances?
Anyone else out there notice this?
(I should note that I recently had an eye exam with a opthamologist. My distance vision is just better than 20/20, an improvement from 20/40 for most of my life. I stopped wearing glasses for distance vision about five years ago.)
