FDA clears first contact lens with light-adaptive technology | Hacker News Reader

FDA clears first contact lens with light-adaptive technology

fda.gov

102 pointsJumpCrisscross57 comments

I'm surprised that a 24 person study was considered large enough for the FDA. I've only worked with 'proper' medical devices with much greater potential for harm, but I'm used to trials involving 100s to 1000s of people.

They submitted via 510(k), a loophole abused by many manufacturers these days. They didn’t have to show this device was safe, just that it’s “substantively similar” to an existing device. The bar for evidence is low-to-laughable.

Is it somehow inappropriate in this case though? Please explain.

That's not correct. You always do safety and efficacy analysis, but with a 501(k) you don't have to stage clinical trials as you would with a PMA. The bar is certainly lower than a PMA, but it isn't laughable.

This is a difficult trade off. If everything went through a PMA as currently defined, we would have a tiny fraction of the devices that we do today, and they would cost orders of magnitude more. The FDA is trying to balance access to beneficial technology with risk, and it isn't an easy line to draw.

Created an account because I am a medical device engineer. You're mischaracterizing 510ks quite a bit. A 510k states that a new device has the same medical indication as a previous device, and you don't have to demonstrate efficacy via clinical trials. In this case the medical indication would be "corrects vision." The darkening is a new feature that is not likely a medical indication.

Regarding safety: You absolutely have to show safety. Any new material, additive, or processing chemical used for an existing indication must be demonstrated to be safe. This also applies if a currently used material is used in larger quantity, or used in a more serious degree of contact (longer duration, more invasive). This is done through biocompatibility testing in accordance with ISO 10993.

Another medical device design engineer here and I second the previous comments that this comment is 100% incorrect.

510k isn't a loophole, shortcut or less safe in any way. Clinical trials are unbelievably expensive, hundreds of millions of dollars or more. Often so much so that they are prohibitively expensive for alternatives to therapies that already exist or for patient populations that aren't large enough to make back the initial investment. Without the 510k pathway much of our modern medical treatment portfolio wouldnt exist as drugs and devices for only the very most lucrative health problems would be cash positive to develop.

Thanks to 510k devices thousands of lives are saved every day, and therapies that were once too expensive for the masses can now be afforded.

Why do you think 24 people is too small a study?

Presumably because between statistical error and the variability of human biology, a problem that affected a large-ish subpopulation would likely not be detected with such a small study group.

They always cherry pick who is included in clinical trials and I don't hear the same complaints about that.

You aren't listening, then, because the fact that clinical trials seek people maximally healthy but for the target conditions rather than a representative sample of those with the target condition is a very frequent complaint.

Where are you seeing this? In every HN thread about some medical trial it is the same complaint about small sample size. It is like a generic complaint thrown by people who don't realize that they are almost all like that...

The agency has to approve your selection criteria and those criteria affect what you can write on your label (i.e. who the drug can be used for). Good example: the Gardasil vaccine is only approved for those under 27 as it was only tested in that age range.

If the device has a 1% chance of eating the user’s brain, that’s probably unacceptably high, but such a study would be unlikely to discover it.

100 people study is also not terribly likely though at 73%. It gets worse - someone’s brain being eaten could be an aberration and you may have to ignore the single outlier, and your detection chances are dropping below 50%

How did you do the math on this?

Independent event probability. A 1% chance of something happening means that there is a 99% chance of the event not happening. 0.99^100 = 0.37. So a 37% chance of no brain eating out of 100 trials. 1 - 0.37 = 0.63, so a 63% chance of a brain being eaten out of 100 trials.

1 - (1 - .01)^100

We're finding the chance that the study will demonstrate brain eating. The hypothesis is that brain eating is rare: .01 chance of that. So any particular subject will probably not display brain eating: .99 chance of that. Assuming brain eating tests are independent, you can raise that quantity to the hundredth power to get the chance that all 100 subjects will not display brain eating. That would be a failure of the test, so subtract that chance from unity to get the test's chance of success.

I'm not sure where the 50% came from off the top of my head, but I think the 73% is wrong (should be 63%).

My math: If there is a 1% chance of something happening in a given sample, there is a 99% chance of it not happening. So, for a set of N samples, you multiply 0.99 * 0.99 * 0.99... N times or 0.99^N to determine the chances of it not happening in any of the samples. 0.99^100 is about 0.37. 1- 0.37 = 0.63.

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?

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

> 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) ?

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-y...

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.

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.

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.

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.

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.

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

(the patent is about making only the center of the lens photochromic, apparently because having the whole lens change color bothers people)

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.

>"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.

"...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.

Most don't, but they do make lenses for people with astigmatism which maintain their orientation.

I have those, I don't think this would be a good use of that because the contacts don't orient themselves very quickly when put in and they're easily reoriented in your eye by simple movements.

You have the wrong brand then. Check with your optometrist because I can assure you, you don't have the live with that problem. It can be fixed. Contacts should retain their orientation at all times unless under extreme duress like you just slept all night in them.

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.

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_...

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.

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.

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

What I'm wondering is how noticeable that will be to other people. Could be weird talking to someone while the contacts are still darkened.

I presume it would make your pupils look super dilated, which could have all sorts of fun implications...

It'd probably just make you look like you have darker eyes.

Shades of A Gift From Earth there. Good novel.

Pretty funny video on the subject https://youtu.be/CXWzpKYXRXM

When you are outside in bright sunlight, your pupils will constrict, so that only a small part of the lens actually needs to darken.

Is there a reason the entire lens has to darken? If they only deposited the dye in a smaller center portion, it would be unnoticeable against a black pupil.

When can we expect to see these available?

This seems like a bad idea. Our eyes have adapted to living with sunlight for thousands of years.

I have a feeling it will be discovered that there is something wrong with darkening your vision for long periods of time.

You mean like sunglasses?

Our eyes have adapted to pure sunlight. But there are scenarios that are fairly new and where our eyes don't work well. E.g. driving on a sunny day, sunglasses can be helpful to see elements both in the (comparably) dark car and the much brighter environment. Your eyes can only adapt to one of those and usually that's the car, leaving you temporarily "blinded" by the road.

When I was wearing transitions glasses I noticed I began to feel SADS-like depression during the spring and the fall. It is hard to explain the feeling that I was just not getting enough light. I began to walk around without the glasses on just so I could get more light, but it wasn't enough. When I started to drive without my glasses I knew it was time to try something else. So I switched to contacts and sunglasses. Will never go back.

Prolonged exposure to sunlight damages the eyes. Cataracts or damage to the conjunctiva for example. We get much older than a few thousand years ago, and our bodies aren't well adapted to dealing with cumulative sun damage.

The existence of eyes for thousands of years in conjunction with the sun does not imply they have impenetrable defenses from the sun. It just means that they're good enough to allow the animal to survive long enough to procreate.

Thousands of years ago, people didn't generally live much past 30 years old. UV has been proven to have negative effects that show up later in life than that.

Where on earth are you getting this? It was certainly not rare for paleolithic women to see their second and third children live to adulthood.

A paleolithic woman would have had her 3rd kid at around 20 years old tops. Seeing that kid to adulthood is still less than 40 years old. Age-related eye problems don't usually show up until you're over 40.

Oh I thought the proposed expectancy was 30; 40 is more plausible. Also, a third viable child produced by 20 indicates a fairly rosy local situation. Every viable child would have nursed for at least two years. Infant mortality was much higher. Menarche took place later than in modern humans. Famine was more common.

One might think that would simply mean that fertility was lower than I'm proposing, but if you look at what paleolithic humans did that is simply impossible. On foot, they occupied every part of every continent save Antarctica. That required fertility significantly above replacement.

Our skin has adapted to living with lions for thousands of years, which is why modern humans are lion-proof.

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