Photosensitive Prescription Glasses

[hpeer]

Does anyone have problems with these??

My specific issue is with my Wife’s ability to read charts. Reading maps and charts is foreign to her and at 70 I am fighting an uphill battle. She is and has always been short sighted, so she really needs glasses. She always gets photosensitive glasses.

It has occurred to me that her glasses may be part of the problem. Yesterday she completely missed a green reef, she read it as blue. But then looking at her glasses I noticed how dark they were, I mean really dark. I got thinking that can not help. I just use dollar store readers, which work better than prescription for me. But I also have non-prescription sun glasses for distance and ALWAYS switch to readers when chart reading. So I have a different experience than she does.

We are using a iPhone or Android for navigation but I have also seen these issues with paper charts.

Does anyone have any experience with this? Can photosensitive glasses interfere with chart reading? Can they degrade the ability to sense/discriminate color? Can the darkness degrade ability to read?

[ranger58sb]

I've not ever had any issues with prescription Transitions-brand photosensitive (photochromic?) eyeglass lenses and charts or chartplotter displays.

OTOH, polarized sunglass lenses raise issues for me, for charts on plotters (less so) and especially tablets and phones (almost always). This is usually a matter of orientation, and if my lenses and plotter orientation match, no issue. Tablets, OTOH, usually need to be either portrait or landscape mode, whichever one is readable depending on my eyeglasses.

I haven't had issues with color on either type of lens.

-Chris

[capt jgw]

Photochromic lenses come in different colors. I always choose the gray kind and haven't noticed any difference in color with them. Been wearing them for decades. I do use clip ons in the car though, the windshield blocks enough UV that they won't go dark.

[thinwater]

There are probably some other issues.
* Electronic chart plotter in the sun (guessing)? Shading can help.
* Bifocals? Can be problematic for many. Single vision can be better for reading.
* Scale. Zoom out too far and important details vanish, like some of the sounding numbers. It's easier sailing to zoom out, but not always safe (remember the Volvo crew that hit a reef?).
* Blue-green color blindness. Her perception may be diminished. Are cataracts a possibility?



Blue vs. green is not going to cause a serious problem if the soundings are there and you are familiar with charts and you are aware the colors are distorted. But yeah, only grey lenses. The only time I have trouble with the colors is red light, so I use very dim white light instead. Just as good for the night vision if it is dim enough (which is the challenge).

[Bobby Lex]

Originally Posted by ranger58sb

OTOH, polarized sunglass lenses raise issues for me, for charts on plotters (less so) and especially tablets and phones (almost always).
-Chris

+1. Tablets and phones are not designed to be viewed through polarized sunglasses.

Chartplotters use a different glass that allows them to be viewed through polarized glasses without difficulty.

A few months ago I was motoring due east at sunrise with an 8" ipad pro running AquaMaps right next to my Garmin 8" chartplotter, while wearing prescription polarized sunglasses specifically designed for sailors and fishermen.

The screen on the ipad looked essentially grey with little contrast or detail through the polarized sunglasses. The Garmin screen looked sharp and clear. I experimented by switching to my regular glasses. I could then see the ipad screen clearly with normal contrast and detail -- but the sun coming up at eye level directly in my face blinded me. So I had to switch back to my sunglasses. Which made my ipad basically useless again.

It's not your wife's fault. She just needs to use a navigation device specifically designed for use with polarized sunglasses.

Bob

[deblen]

Possible solution:
https://www.magnifier.com/chart-map-magnifiers.htm

[Tom_F]

Originally Posted by capt jgw

Photochromic lenses come in different colors. I always choose the gray kind and haven't noticed any difference in color with them. Been wearing them for decades. I do use clip ons in the car though, the windshield blocks enough UV that they won't go dark.

That's generally been my experience as well, and I, too, choose grey whenever possible. However, I have tried brown transition lenses and green transition lenses where colors were sometimes altered and my brain had to work harder to overcome the color shift caused by those lenses. I can see how if that happened reading a chart it could be disastrous in the wrong circumstances.

[Jammer]

The main problem with photosensitive glasses is that they take a long time (minutes) to turn clear after sun exposure.


You wife may have mild colorblindness that is contributing to difficulty reading charts. It might be a good idea for her to talk to her optometrist about that before going too far down the road. There are mitigations available if that is the problem.


I would suggest using a bright flashlight when reading charts, if the glasses haven't cleared completely. There are some good LED flashlights that have a high CRI and don't distort colors. Take a look at the Four Sevens Preon P2 -- it's my favorite for that sort of thing.

[Mirage35]

I tried the grey and the yellow and found both far too dark for me, especially with the sun in front of me. I regularly had to remove my glasses (they're primarily for reading) to see where I was going.

One more data point anecdote.

[Jebtrois]

We use the peel and stick magnifiers on our non-prescription sunglasses of choice.
JEB

[hpeer]

Thanks guys.

It seems consensus is glasses are of no issue, except one reported the glasses were too dark.

Her glasses are NOT polarized, this particular event occurred mid day, sunny, her glasses were DARK.

She does seem to have some mild color blindness, maybe. Ot maybe we just call things different colors. Guys know like 12 colors while women have hindreds if shades.

I will need to look elsewhere to improve her chart reading. It has been a problem at times. Something is going on I do not get. Charts are just impenetrable to her, I am seeking why. “Why” is impenetrable to me.

Bottom line is she can not reliably read a chart and we have come close to serious grief more than once. She is very bright, draws very well, gives a damn, and yet repeatedly fails. I am stumped.

I am trying to have here read the chart (iPhone) following our path. We were coming up on a small island with some off lying rocks and a reef. I had her look at the chart, she found the island, and the shoals, and insisted I had a minimum of 3 meters over the shoal with no other obstructions. So she totally missed the reef and the X’s for the rocks. One of many, many examples, some more dangerous.

We have been at this for years. As I said, I am stumped.

[ranger58sb]

Originally Posted by Bobby Lex

The screen on the ipad looked essentially grey with little contrast or detail through the polarized sunglasses. The Garmin screen looked sharp and clear. I experimented by switching to my regular glasses. I could then see the ipad screen clearly with normal contrast and detail -- but the sun coming up at eye level directly in my face blinded me. So I had to switch back to my sunglasses. Which made my ipad basically useless again.

You could try rotating your tablet 90°.

-Chris

[Mike Crothers]

I would also suggest that you review your route ahead of time and mark with waypoints the issues along that route such as reefs or obstructions.


I find waypoints standout and don't scale down. We have a setting that puts the waypoint name on the chart so you can quickly see the nature of the danger that is included in the waypoint name. Example WP359 Shallow Reef to the West.

[Tupaia]

If your chart plotter and or charts are inside or shaded then as said the photchromic lenses introduce a considerable delay. Here is another suggestion.

My wife had the same problem until she replaced her pc glasses with clear ones and uses "fit over" sunglasses that can be quickly removed or lifted up to see chart details.

[Chotu]

Speaking of tablets and phones and screens like that, why don’t you download an app or something like that to give her a color blindness test? I’m sure they have them. Maybe that’s all that’s wrong.