4 ms·

Not sure if that's a great idea. If you wear sunglasses (or light-adaptive glasses), you can still take them off quickly. E.g. when driving against the sun and

by dx034 9y ago

Not sure if that's a great idea. If you wear sunglasses (or light-adaptive glasses), you can still take them off quickly. E.g. when driving against the sun and entering a tunnel, taking off the glasses help to be able to see the road. With contact lenses, I could imagine that you'd be basically blind for at least a few seconds?

xxs 9y ago
If you are behind a glass windshield it should not matter all that match (glass is almost black for UV [and infrared]). At least I have never had issues with similar glasses. The contact lenses contain a photochromic additive that adapts the amount of visible light filtered to the eye based on the amount of UV light to which they are exposed
- Jaruzel 9y ago
  > glass is almost black for UV [and infrared] If this is true, then why does my right arm always get more tanned than my left when I drive in the summer (UK, right-hand drive) ?
  - koolba 9y ago
    Different type of glass[1]. The windshield had a layer of plastic in between that absorbs the UV. The side windows are regular glass. [1]: http://www.tampabay.com/news/health/do-car-windows-protect-you-from-the-sun/2139733 http://www.tampabay.com/news/health/do-car-windows-protect-y...
    - Retric 9y ago
      Even side windows block ~65% of UV light, it's really more about exposure though as people may spend a lot more time driving than walking outside.
- geoelectric 9y ago
  Can't speak for the contacts but Transitions Xtractive also react to visible light, albeit not as strongly as for UV. Mine tint noticeably behind a windshield or inside a motorcycle helmet (and, unfortunately, large-windowed conference rooms). Never had issues in tunnels or buildings such that I needed to remove them though.
sohkamyung 9y ago
The lenses (like glasses) darken based on the amount of UV light to which they are exposed. Car windows usually have some UV filters so such lenses don't usually darken much in cars, even in bright sunlight and don't usually pose a hazard when suddenly moving to dark areas like tunnels. However, it might be different if you're driving in an open-top car, which would expose the lenses to UV and cause them to darken much more.
- azernik 9y ago
  The issue is response time - if you go from a bright area to a dark one, you're stuck for 2-10 seconds (depending on quality of lens) of a very dark field of view.
JumpCrisscross 9y ago
As someone who hasn't driven since 2012 and frequently forgets his sunglasses, I could see these being useful. My chief concern is around the chemical leaching into the eye, e.g. if the lens tears or on day 365 of a one-year supply.
- maxerickson 9y ago
  I imagine the dye is bound up in the polymer (it's a soft lens). In that case ongoing migration would be a similar problem as tearing. That's how one of their patents sounds: https://patents.google.com/patent/US7261844 https://patents.google.com/patent/US7261844 (the patent is about making only the center of the lens photochromic, apparently because having the whole lens change color bothers people)
bdamm 9y ago
When wearing transitions I would often remove my glasses and pocket them a minute or two before entering a building, so that I could don the glasses as soon as I entered. When riding a motorcycle while wearing the glasses the darkening was significant and was unnerving to ride from a bright section of road to a deeply shadowed section. The effect was similar in a car but windshields do block more UV than a visor. If someone is willing to wear contacts I can't see why they wouldn't just don sunglasses. Intriguing product but uncertain of what applications exist. Perhaps the deeper meaning here is the additive process. Also noteworthy is that the dye could be laid unevenly so that some areas of the contact are more affected, such as only in the top 1/3rd.
- KozmoNau7 9y ago
  >"If someone is willing to wear contacts I can't see why they wouldn't just don sunglasses" That was actually my primary reason for trying out contacts; I wanted to be able to wear affordable sunglasses, and not have to keep around a case if I needed to change back to my regular glasses. Not having to worry about fogging would be a huge benefit as well. There is no actual good sunglasses solution for people who uses glasses, outside of carrying around a separate pair of prescription sunglasses. Unfortunately, I just couldn't get used to the contact lenses, even after a month of trying all of the various types, from complete basic to the fancy high-end silicone. I had no troubles putting them in and taking them out, but my eyes would be irritated and tired around mid-afternoon, no matter what. I also realized that my subscription (-0.75/-1.00) is basically perfect for computer work if I take off my glasses, so consequently I hardly ever wear them indoors. With contact lenses, I would negate that benefit and have to constantly focus, giving me headaches after a couple of hours. Obviously I could correct that back with a pair of +1.00 reading glasses, but that does seem a bit silly, really. So yeah, if I wore contacts, I would definitely just use a pair of cheap (UV-rated, obviously) sunglasses and not worry too much about them. These color-changing lenses seem too expensive and have too many downsides.
- delinka 9y ago
  "...such as only in the top 1/3rd." Contacts don't stay "upright" in the eyes, so I'm unclear how this would be at all beneficial.
skywhopper 9y ago
Lots of people have poor enough eyesight that taking off their glasses is not a reasonable option. Transitions lenses do not get so dark that this is a major concern. Also, the vast majority of people don't drive through tunnels regularly.
- cmiles74 9y ago
  I hear you on the transition lenses comparison and I agree. IMHO, people go through a lot of tunnels all the time. As far as I can tell, they are pretty spread out geographically. I mean, tunnels are pretty common.[0] [0]: https://en.wikipedia.org/wiki/List_of_tunnels_in_the_United_States https://en.wikipedia.org/wiki/List_of_tunnels_in_the_United_...
  - selectodude 9y ago
    I can’t think of a single time where I’ve been in a tunnel that’s so dark that I can’t see anything wearing slightly tinted sunglasses. The only reason I take them off is because socially, it’s a bit weird to have them on while on an underground subway train.
dnh44 9y ago
Photochromic dyes fade back pretty quick when they’re warm so they should fade back much quicker than the ones in eyeglasses since they will be at body temperature. Also the performance is normally faster in soft substrates and I imagine this will be a soft contact.
BurningFrog 9y ago
Close one eye while staring at the sun, and you'll be fine in the tunnel.

by dx034 9y ago

xxs 9y ago

If you are behind a glass windshield it should not matter all that match (glass is almost black for UV [and infrared]). At least I have never had issues with similar glasses. The contact lenses contain a photochromic additive that adapts the amount of visible light filtered to the eye based on the amount of UV light to which they are exposed

Jaruzel 9y ago
> glass is almost black for UV [and infrared] If this is true, then why does my right arm always get more tanned than my left when I drive in the summer (UK, right-hand drive) ?
- koolba 9y ago
  Different type of glass[1]. The windshield had a layer of plastic in between that absorbs the UV. The side windows are regular glass. [1]: http://www.tampabay.com/news/health/do-car-windows-protect-you-from-the-sun/2139733 http://www.tampabay.com/news/health/do-car-windows-protect-y...
  - Retric 9y ago
    Even side windows block ~65% of UV light, it's really more about exposure though as people may spend a lot more time driving than walking outside.
geoelectric 9y ago
Can't speak for the contacts but Transitions Xtractive also react to visible light, albeit not as strongly as for UV. Mine tint noticeably behind a windshield or inside a motorcycle helmet (and, unfortunately, large-windowed conference rooms). Never had issues in tunnels or buildings such that I needed to remove them though.

sohkamyung 9y ago

The lenses (like glasses) darken based on the amount of UV light to which they are exposed. Car windows usually have some UV filters so such lenses don't usually darken much in cars, even in bright sunlight and don't usually pose a hazard when suddenly moving to dark areas like tunnels. However, it might be different if you're driving in an open-top car, which would expose the lenses to UV and cause them to darken much more.

azernik 9y ago
The issue is response time - if you go from a bright area to a dark one, you're stuck for 2-10 seconds (depending on quality of lens) of a very dark field of view.

JumpCrisscross 9y ago

As someone who hasn't driven since 2012 and frequently forgets his sunglasses, I could see these being useful. My chief concern is around the chemical leaching into the eye, e.g. if the lens tears or on day 365 of a one-year supply.

maxerickson 9y ago
I imagine the dye is bound up in the polymer (it's a soft lens). In that case ongoing migration would be a similar problem as tearing. That's how one of their patents sounds: https://patents.google.com/patent/US7261844 https://patents.google.com/patent/US7261844 (the patent is about making only the center of the lens photochromic, apparently because having the whole lens change color bothers people)

bdamm 9y ago

When wearing transitions I would often remove my glasses and pocket them a minute or two before entering a building, so that I could don the glasses as soon as I entered. When riding a motorcycle while wearing the glasses the darkening was significant and was unnerving to ride from a bright section of road to a deeply shadowed section. The effect was similar in a car but windshields do block more UV than a visor. If someone is willing to wear contacts I can't see why they wouldn't just don sunglasses. Intriguing product but uncertain of what applications exist. Perhaps the deeper meaning here is the additive process. Also noteworthy is that the dye could be laid unevenly so that some areas of the contact are more affected, such as only in the top 1/3rd.

KozmoNau7 9y ago
>"If someone is willing to wear contacts I can't see why they wouldn't just don sunglasses" That was actually my primary reason for trying out contacts; I wanted to be able to wear affordable sunglasses, and not have to keep around a case if I needed to change back to my regular glasses. Not having to worry about fogging would be a huge benefit as well. There is no actual good sunglasses solution for people who uses glasses, outside of carrying around a separate pair of prescription sunglasses. Unfortunately, I just couldn't get used to the contact lenses, even after a month of trying all of the various types, from complete basic to the fancy high-end silicone. I had no troubles putting them in and taking them out, but my eyes would be irritated and tired around mid-afternoon, no matter what. I also realized that my subscription (-0.75/-1.00) is basically perfect for computer work if I take off my glasses, so consequently I hardly ever wear them indoors. With contact lenses, I would negate that benefit and have to constantly focus, giving me headaches after a couple of hours. Obviously I could correct that back with a pair of +1.00 reading glasses, but that does seem a bit silly, really. So yeah, if I wore contacts, I would definitely just use a pair of cheap (UV-rated, obviously) sunglasses and not worry too much about them. These color-changing lenses seem too expensive and have too many downsides.
delinka 9y ago
"...such as only in the top 1/3rd." Contacts don't stay "upright" in the eyes, so I'm unclear how this would be at all beneficial.

skywhopper 9y ago

Lots of people have poor enough eyesight that taking off their glasses is not a reasonable option. Transitions lenses do not get so dark that this is a major concern. Also, the vast majority of people don't drive through tunnels regularly.

cmiles74 9y ago
I hear you on the transition lenses comparison and I agree. IMHO, people go through a lot of tunnels all the time. As far as I can tell, they are pretty spread out geographically. I mean, tunnels are pretty common.[0] [0]: https://en.wikipedia.org/wiki/List_of_tunnels_in_the_United_States https://en.wikipedia.org/wiki/List_of_tunnels_in_the_United_...
- selectodude 9y ago
  I can’t think of a single time where I’ve been in a tunnel that’s so dark that I can’t see anything wearing slightly tinted sunglasses. The only reason I take them off is because socially, it’s a bit weird to have them on while on an underground subway train.

dnh44 9y ago

Photochromic dyes fade back pretty quick when they’re warm so they should fade back much quicker than the ones in eyeglasses since they will be at body temperature. Also the performance is normally faster in soft substrates and I imagine this will be a soft contact.

BurningFrog 9y ago

Close one eye while staring at the sun, and you'll be fine in the tunnel.