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Queens College, City University of New York ​awesome thank you guys so much for coming out here to listen to our discussion here so we're gonna present our project which was UV dimming contact lenses we're really excited to talk about this so we'll give you a quick overview what we're gonna go into before we dive into all the details here so if next so to start we're gonna go over an introduction and kind of talk about current products on the market and why we think our product is kind of a good solution to some of these the flaws that current products exist from there we'll go on to our actual product which is the UV dimming contact and then after that we'll dive a bit more into some of the details such as how we make these what the properties are and why why these are actually good properties and and how these satisfy our requirements so the next slide so as we all know the Sun is a pretty good thing it can be a lot of fun to spend the day in the Sun but unfortunately the Sun is also quite harmful as it emits dangerous UV rays these can cause all sorts of health issues with your skin and your eyes arranging from cataracts so right now there are really two solutions that exist on the market one is to use sunglasses which are great when you're outside but as soon as you step inside the sunglasses become effectively useless and you have to take them off an alternative solution to try to solve this has been the introduction of transition lenses and these are normal eyewear that transition to a darkened state upon exposure to UV such as walking outside the problem with this solution is that they take minutes to transition it isn't a fast transition so by the time you're outside either they finally get dark you're probably gonna be coming in and then you have to wait for them to clear up again in addition to these issues with the solar radiation there are other issues and that's with the fact that they're actually large bulky glasses that have to go on your face so often when we need sunglasses the most is when we're outside having fun and that's often when we don't want to have something on our face you would would you rather play volleyball with something on your face like sunglasses or not have anything at all would you want to go surfing with sunglasses and also golfing with sunglasses is a big issue because they can often fall off when you're swinging and this it's just not a good situation so based on these things we're proposing a new so an entirely new solution to this problem using contact lenses so contact lenses are widely used across the world they're commonly used and they've they've been in place for a long time so the issue is they don't really do much when it comes to UV radiation or solar radiation some of them block out UV radiation but you're still left squinting and often have to put sunglasses on top of your contact lenses so what we're proposing is a UV dimming contact lens a contact lens that blocks out solar radiation a contact lens that transitions instantly as soon as you walk outside to a darkened state and then returns as soon as you walk back in the great thing about these contact lenses is that they have an incredibly fast response time these will change to a darken state within seconds as opposed to the minutes of normal transition glasses they're made with standard contact lens materials so they're durable and they're comfortable just as you would expect that also makes them very safe because we're using biocompatible polymers such as Hema and GMA so we're all this is standard contact lens materials so we're not really changing much we're simply adding a little bit of a special ingredient if you have the next slide so to give you a demonstration of how these actually work we have a quick video to show it off so here we have our lenses and we've exposed them to UV light as you can see they begin to start darken one thing to note is that these lenses the UV light used in this demonstration isn't as strong as that we is the one we have in the booth so if you get a minute I would recommend you come check out our booth we have a more representative example of where we're at with these so you can see they're darkening they're turning blue and then we turn off the UV light in a second here and it goes off and then you can see they instantly become to fade I'd also like to point out that they do get a lot darker and our booth it's just due to the strength of the UV light we're using at this moment so from here you're probably asking how does this transition actually happen well we use something called a photochromic die specifically a natural peer instruction Athar pyrin that undergoes structural changes when exposed to UV light less than 380 nanometers this additional UV light causes an energy increase in the molecule which results in a structure change the biggest issue with this die and the reason that these dyes haven't been used more often is because they're actually very sensitive to water and they can degrade in water obviously for a contact lens this is kind of a bad thing you don't want contact lenses are used in aqueous

environments so how are we gonna put this diet in an aqueous environment such as a contact lens well we've developed a novel nano emotion and this nano emotion effectively protects the dye against water by separating it through putting it in the organic phase so as you can see here we have an idealized cartoon version of what our by continues emotion structure looks like you can see the domain pitch should be around a hundred nanometers Alex will go into why that's the reason a little bit later you can see on the right we have our SEM image that shows structures that are more on the micro size features but once again Alex will talk more to that you can see our organic phase contains the photochromic diet as previously stated along with our kima polymer our cross linker all of our polymer action is in that organic phase and then our equus phase is what contains the water so we were able to actually effectively separate this photochromic dye from the water to protect it and make it make sure it lasts long all day long so to give you a quick introduction to how we actually make this we've created this little animation here so you can see here we'd simply take our organic phase sonic ate it and then we mix our aqueous phase very simply and then sonic ate that this is a very easy synthesis it's a very fast and it's also probably scalable we just add it to a contact lens mold and then cure it at 60 degrees for one hour and we have a contact lens that changes color in the sun alex is gonna go over some of the details and some of our test results from this project Thanks thanks Matt so as Matt mentioned earlier one of the biggest competitors to this product would be transition glasses they do pretty much the same thing they dark when you go outside clear when you go inside except they sit on your face instead of on your eye so we want to kind of compare the transition times between these transition glasses and the and our contact lenses so what we did was we took both and we put them under the same UV light and we measured their darkness oh as a function of time whether darkness in the plots there are normalized to their maximum darkness and something that may jump out to you from the plots is that our product which is the red curve actually transitions much much quicker than the black curve which the transition glasses actually our results show that they transition over 50 times faster you can see this especially shows in the 50 percent clearing time for our contact lenses it's only three seconds whereas for transition lenses it can be one hundred and fifty seven seconds or more so picture you're wearing transition glasses you have just come in from outside and two minutes later you're still it's still dark everywhere you're like I can't see anything with our contact lenses you'd walk inside and just like that within three seconds you'd be able to see everything clearly again so the next thing I'd like to talk to you about is kind of the comfort aspect of the contact lens obviously we want the lens to be comfortable for the user to wear and one of the kind of main factors in this is how well the contact lens adheres to the tear film of the eye if it doesn't it here very well then the user is going to feel like they have something in their eye the entire time which obviously is not a desirable feeling for somebody wearing a contact lens so to determine kind of how how well Villains adheres to this tear film you have to determine the wettability and the wettability is obtained by measuring the water contact angle this angle can be measured a variety of ways the way we chose was using the solid drop test so you can kind of see an image of it here so here's the water droplet on top of our contact lens which is this surface here and you can kind of see the blue lines here indicating the angles that the water that the droplet is making contact with the surface of the lens to consider a lens to be comfortable you generally want 1/4 contact angle of below 90 degrees all of our lenses were below 90 degrees with an average contact angle of 49 degrees so by this metric our lenses it could be considered to be comfortable so let's say you go to open up your contact lens or open up your contact lens case you go to put in your eye and it rips you can't have a tauren contact lens in your eye or let's say UV blinking the stress of blinking over the day ends up tearing the contact lens newer these are good scenarios so we want to make sure that the durability of our contact lens kind of matched up with the contact lenses that are commercially available now the way that we measured this durability was by performing a tensile test to determine the tensile strength so maybe wondering what is this tensile test is essentially where the material is gripped at two ends and pulled and the amount of stress needed to deform the material is measured you can see these two plots here we have these are two different samples that we put through this tensile test now the on the y axis is stress on the x axis is a strain and something I want to point out we've highlighted the areas where the tensile strength is which is the maximum stress that had been applied the material that's what's defined as the tensile strength and both are around point 7 mega Pascal's as you can see from what's expected industry of 0.36 to 1.5 9 mega Pascal's this point 7 actually fits very nicely in between those those limits so these contact lenses are just as durable as contact lenses currently available so let's say you know your lens doesn't rip when you put your eye that's great let's say you take it at the end of the day and along with a bunch of other health implications your eye now changes color when you go out into the Sun well obviously we don't want the dye to leech out of the hydrogel that would be a big safety issue so to kind of simulate a use case and storage we left these we took three hydrogels each of a different concentration of dye centered around our standard dye concentration and we just let them sit in water for two weeks now what one would expect if the dye were to leech out of the gel out of the

hydrogel you'd expect to see a similar absorbance curve for the water as you would for as you would for the dye now on the left here you can see the the absorbance curve for for the dye and you can see it's between 400 and 650 nanometers now on the right side are the results of our test so you can see over this over the dye absorbance region there is no absorbance measurable from this we can say that the diet is not leach out of our lens this is even after two weeks of being soaked in in water so another thing is that well we it's nice that we kind of dim we make it more comfortable for the user that all this the brightness has been reducing that but we asthma mentioned there's also very harmful UV rays coming out of the Sun especially the deeper so the shorter the wavelength the deeper into UV the more harmful these rays are so what we want to do was kind of reduce the amount of UV that was getting to the eye even further and we did that by adding the UV blocker the UV blocker that we added was benzophenone you can see the absorbance curve here so it actually starts absorbing at 300 nanometers and peaks at around 250 which is closer to the deeper edge of the sun's UV emission now you may be wondering okay we added a UV blocker to a lens that requires UV light to become activated well actually so the asthma I mentioned previously the dial is activated by light that's 380 nanometers or less and as you can see here this benzophenone has no absorbance over over that region and so the die can still be activated and all the tests we've shown you so far have been performed with this UV blocker in place so as you may have recognized from a couple of the pictures the lens is not completely transparent it's actually a little cloudy so we know kind of why this is this is actually due to us having a micro-emulsion instead of a nano emulsion now you're probably wondering okay what what difference does that make white is having an animal should make it transparent well it's actually related to the size of the particles in the emulsion to oil the oil phase and so as the as the size of a particle becomes larger on the same order of magnitude as the wavelength of light reaching it or even or even bigger the the light gets the lake gets scattered fairly evenly so you can imagine that for our size particles which is around micron it would scatter all visible light which is between about 400 to 700 nanometers so you can see I have an animation here kind of showing the scattering and so this is called me scattering and this is kind of you can see all the wavelengths being scattered there now when you have smaller particles you enter the domain of Rayleigh scattering and so with Rayleigh scattering the the degree of scattering actually decreases as the wavelength increases so if we have particles that are under 100 nanometers you can actually see that the U while the UV does get scattered the longer way the visible wavelengths are too long to be they're not affected by the scattering as much which allow them to pass through and which would allow us to have a transparent hydrogel the reason we weren't able to achieve this Nano emulsion was because of instrument limitations and they're what we would have needed Matt mentioned before that we Sonic 8 we would have needed a smaller tip size to provide enough energy to kind of create those nano sized particles unfortunately that wasn't within our budget so we kind of worked with what we had and were able to create this micro-emulsion but obviously a next step would include trying to get this transparent hydrogel and so just to kind of summarize our group has developed a UV activated dimming contact lens which darkens when you go outside and clears when you come back inside this is very useful for sports such as volleyball basketball golfing surfing a whole a whole bunch where basically it would be impractical to wear sunglasses this was achieved by embedding a photochromic dye into an emulsion hydrogel and not only did it reach did the contact lens reach most of the functional specifications we set it early on in the project it also turned out to be much faster than transition lenses providing this added benefit future steps would include trying to get that transparent hydrogel getting the nano emulsion as well as trying out different dyes thank you very much [Applause] [Music] so this in terms of darkness so this is about as dark as it gets with the kind of dye that we've played around with in terms of loading it into the matrix now this is for the this color is called Oxford blue there are other color dyes such as a volcanic gray in that that can be added to make it even darker we want to kind of stick to one dye for now so this is we weren't able to get transmission test just because the lenses were cloudy so this is kind of a visual appearance that's why we normalize the darkness of visual appearance is kind of this is about how dark it's going to get no be just because we just because we weren't able to I guess to get those transmission tests we weren't we couldn't yeah it's it's not transparent us we can't really see we can only see how dark the dye got different colors of diets I don't know if I was mentioned we so we can have blue green purple so we can also market it as kind of an aesthetic feature as well we yeah we actually discussed that so we've been working with the Center for contact-lens research in the optometry building and we were going to test the oxygen permeability with it but they didn't they kind of explained to us that there wasn't really a standardized process or a standardized machine for that so they said that's there's probably kind of outside the scope of what we have here in terms of facilities so they said they recommended probably maybe that's something you guys sound like that later down the road but right now I just really focus on what makes it special that's the UV light but yeah we've designed it using contact lens materials so from the start so with without intention we imagine it should be pretty pretty similar to normal contact lens oxygen permeability I'll bring up this slide here it takes less than

five seconds though so you can see here when we compare it to transition glasses it's essentially instant Oh like the number of times thick cycles yeah so we've done it so they do actually degrade after a while so we're kind of marking them as daily lenses so definitely within using them within one day you're not going to hit that limit but we've been we've tested them for four months now and really we haven't seen significant degradation really in terms of cycling I don't know if you it's only really been in terms of store like we stored them in water for four weeks and that's when we started to see the degradation in terms of cycling we have the lenses at our booth we've been doing them all day every time somebody comes by we kind of demo the the cycle and turn an offer on for five seconds then turn it off on these lenses we've actually also been testing over the past week just to make sure they're ready for the for the symposium so they they've been able to withstand they have integrated over yeah oh thank you thank you so much Touro Law Center.