Transition Contacts in Action
Paavan Kotini, Mike Matthews,
Raj Ganguly, Sam Leu, Jung Lee
The need-Coming Outside
The need- Military
The need- Athletes
• At time uv light can
impair actions. The
goal of this project is
to use previous
incumbent technology
of transition glasses
and apply it to
contacts.
General Mechanism of Photochromism
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mechanism over the course of the colour change, the photochromic
molecule represented simplistically as two rings.
Upon the action of UV light or direct sunlight, the structure twists
from a perpendicular (closed) form to a flat, planar (opened)
structure. This allows the two halves to interact, resulting in the
absorption of visible light.
There are effectively two changes occurring simultaneously; a
chemical change arises when the molecule is exposed to UV light,
that enables conjugation to take place throughout the molecule; a
structural change also occurs to enable the overlap of ∏-orbitals.
Therefore, spatially, the molecules must be able to flatten out to
allow this conjugation to take place.
It is a fully reversible reaction so that when the light source is
removed, the molecule returns to its uncoloured state. Heat can also
help drive the reaction back to the uncoloured form, so in very hot
conditions, there is always competition between light and heat to
determine the given colour observed. In general, a colour change is
still observed, albeit weaker than at room temperature. Similarly, in
cold conditions in the presence of sunlight, an intense colour is
observed as there is little or no competition from the back reaction.
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Kinetics
This is a cyclic reaction and the number of cycles (or the activation
and fade rates) varies greatly by product. The activation times are
generally much shorter than fade times. On average, fade times are
two or three times longer than activation times. The Reversacol
product range offers a very large variation in kinetics characteristics.
Some fade in several seconds, whilst others can take several
minutes.
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Systems
As well as the nature of the product influencing the colour and
kinetics result, the system or matrix used with the dye has a strong
influence on such properties. For example, in some systems, a
colour shift of up to 20nm has been observed.
http://www.photochromics.co.uk
James Robinson Reversacol Photochromic Dyes
Market Research
• Current solutions include: sunglasses,
contact lenses with UV protection, and
transitioning eyeglasses.
• Each confers benefits to the user, but fails
to bridge the gap in technology for low and
high intensity situations; or provide an
optimum level of convenience.
Market Research
Vision-Corrected Market by Year vs. U.S. Population (Millions)
Source: Health Products Research, Inc
• Since 2002, market reports (e.g Optistock.com) show that the
demand for contact lenses has been growing; especially specialty
contacts, which currently account for one-third of the world demand
for contact lenses.
• Unfortunately these specialty contacts fail to reduce glare in the
user’s eyes, making it necessary to use other sun light intensity
reducing technologies (e.g sunglasses).
Market Research
Nike MAXSIGHT™ lenses by Bausch & Lomb
Source: http://www.nike.com/nikebiz/nikebiz.jhtml?page=2&item=maxsight
http://www.bausch.com/us/vision/products/softcontacts/nikemaxsight_faq.jsp
http://www.flinthillseyecare.com/pdf/Maxsight_Nike_CL.pdf#search='nike%20maxsight'
Market Research
• Possible Cost for production of transition
contact lens
• Selling price of product would be between
$40 and $60 dollars for 2 boxes of Contact
Lens
PMMA Polymethacylate
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PMMA or polymethylmethacrylate is a clear plastic vinyl polymer that is more
transparent than glass.
PMMA has been used safely for almost 50 years for contact lenses.
Advantages
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Studies with spiropyrans and spiro-oxazines show that it does not slow down UV response
times of Photochromic pigments.
It is also water soluble
It is able to readily bind with the pigment
Disadvantages
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not very gas permeable( very low oxygen penetration)
low elasticity
Silicon Hydro Gel
• An inorganic matrix of
silicon dioxide.
• Used in creating current
soft contact lenses
• Advantages
– It allows the contact lens to
have greater flexibility
– Allows for greater oxygen
penetration
• Disadvantages
– Is not very compatible with
the photochromic pigment
• Slows down transition time
• The binding process is
complicated
Poly-HEMA
• Used as backbone for
many hydrophilic
contact lenses
• 1st to be used in
hydrophilic contact
lenses
• Very stable and safe
material once
polymerised
Polydimethylsiloxane (PDMS)
Elastomer
• [SiO(CH3)2]
• Widely used siliconbased organic
polymer
• Optically clear,
considered to be
inert, non-toxic and
non-flammable
1′,3′-Dihydro-8-methoxy-1′,3′,3′-trimethyl-6nitrospiro[2H-1-benzopyran-2,2′-(2H)indole]
•Type: Spiro-pyran
•Molecular Weight: 352.4 g/mol
•Melting Point: 159 – 162 °C
•Price: $40.50 per 1g (Sigma Aldrich)
1′,3′-Dihydro-1′,3′,3′-trimethyl-6-nitrospiro[2H-1benzopyran-2,2′-(2H)-indole]
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Type: Spiro-pyran
Molecular Weight: 322.36 g/mol
Melting Point: 179-180 °C
Price: $68.40 per 1g (Sigma Aldrich)
Toluene
• Appearance: Colourless liquid
• Melting point: -93 C
• Toxicology– Toxic by inhalation, ingestion or absorption
through skin. Serious irritant
• Widely use as a solvent
• Evaporates during procces of making
contact
Process of Making Contact Lens
• PDMS monomer to Curing Agent
• 1 Monomer : 5 Curing Agent
• Mix Monomers with Curing Agent
Chemical in PDMS Soluble Test
• Dissolve chemical with toluene
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0.5 mg of Chemical
400 µl of toluene
≈0.3 ml of PDMS
≈0.066 ml of Curing Agent
Surface Coating
• Make PDMS
• ≈0.5 mg of Chemical
• 100 µl of toluene
Chemical Vapor Deposition
Concentration Experiment
• Pigment 1
• 0.001,
Mold Making
• Contact Vanderbilt
Machine Shop
• VIIBRE
– Use Epoxy
– Use Crystal Clear
• Design Usage
– mass production of
contact lens
Mixing of two Chemicals
Future Direction
1. Radial limiting of pigment deposition
2. Safety, will be testing leak rate in saline
solution.
3. Safety in terms of lesions, eye irritation,
and chemical reactions in live animal eyes
4. Human testing via FDA approval
5. Manufacture Demonstration Contact Lens
d= 30mm (Area ~ 9 X of normal contact
lens)
References
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http://www.contamac.com/db/display/glossary
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http://www.bimax.com/hema.htm
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http://www.polymer.org.au/uqchem/hydrogels.html
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http://chemweb.calpoly.edu/chem/gragson/Teaching/chem354/Lab_instructions/Photo
chromism.pdf#search='Spiropyrans'
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http://www.thieme-connect.com/ejournals/pdf/synfacts/doi/10.1055/s-2005869881.pdf#search='Spiropyrans'
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http://www.freepatentsonline.com/4826977.html
(Photochromic spiropyran compounds , United States Patent 4826977)
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http://pubs.acs.org/cgi-bin/abstract.cgi/jpchax/1972/76/i24/fpdf/f_/j100668a007.pdf?sessid=6006l3
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http://www.photochromics.co.uk/index.htm
References
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Lay Gaik Teoha, Jiann Shiehb, Wei Hao Laia, I Ming Hunga, Min Hsiung Hon.
“Structure and optical properties of mesoporous tungsten oxide.” Journal of Alloys
and Compounds. (2005) 251–254
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Robert G. Palgrave and Ivan P. Parkin. “Aerosol assisted chemical vapour deposition
of photochromic tungsten oxide and doped tungsten oxide thin films.” Journal of
Materials Chemistry. 2004, 14, 2864 – 2867
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http://www.freepatentsonline.com/5458815.pdf
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S. Delbaere,a, J.-C. Micheau,b Y. Teral,c C. Bochu,a M. Campredon, c and G.
Vermeerscha. “NMR Structural and Kinetic Assignment of Fluoro-3H-naphthopyran
Photomerocyanines.”
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www. Alcok.com/intac.html
Andersson, Nina, Alberius, Peter, Ortegren, Jonas, Lindgren, Mikael, and Bergstrom,
Lennart. “Photochromic Mesostructured Silica Pigments Dispersed in Latex Films”