CHEN 90038
Product Design and Analysis
2022 Semester 1


Eye Contact Lens








2

Table of Contents
1. Abstract ................................................................................ 3
2. History and Background ....................................................... 3
3. Results and Discussion ......................................................... 5
3.1. Mode of Operation ......................................................... 5
3.2.Technical Attributes ........................................................ 5
3.3. Ingredients ...................................................................... 6
3.4. Manufacture ................................................................... 8
4. Future Development of the Product .................................. 10
5. Reference ........................................................................... 11
6. Appendix ............................................................................ 13

3

Abstract
As a widely used device for vision assistant, the contact lens is one kind of soft
matter which helps improve the life qualities of those who are suffered vision
difficulties. Since the 16th century, contact lens has been developed as a
theory. It has been recorded that the first version of contact lenses was made
from material glass. Afterwards, various materials, particularly polymers, were
extensively explored and used in research and production. In current available
market, there are two basic and common varieties of contact lenses which are
soft contact lenses and rigid contact lenses. The former has a hydrophilic
structure, whereas the later has a hydrophobic structure. In this report, the
product including mode of operation, technical attributes, common
ingredients, and production methods are introduced, as well as the evolution
of the products in the future and its related applications.

History and background
In 1508, Leonardo da Vinci who is an Italian inventor, discovered the concept
"Codex of the Eye", in specific, water could alter the vision if the head is
submerged in a bowl of water. Then, he made an experiment by using a glass
lens with a funnel which could be filled with water. However, the device design
was totally a failure unfortunately, looked very hilarious. By learning from
previous work from Leonardo, René Descartes, he presented an alternative
one in 1636. He decided to insert a glass tube filled with liquid, but this time is
different, the surface of the eyes were directly contacted, the cornea.
Therefore, the lens was later called a “contact lens” (1800contacts.com, 2022).
4

F. A. Mueller, an artificial eye maker, created the first tangible specimen of the
lens in year 1887. They were named as scleral lenses because they could cover
the entire eyes rather than the cornea. Like Da Vinci's bowl of water, they were
slightly in the position of convex, allowing the solution which contains tears—
to generates the refractive power to help the vision correction. In 1888, Dr Fick
created the first effective contact lens and his lenses had two fundamental
flaws: the lenses were constructed of glasses which are heavy and were about
20mm in diameter. They were hard to wear just because of their weight, but
surprisingly, the exposed eye was entirely covered by lenses in this experiment
(1800contacts.com, 2022).
In 1929, Dr Dallos and Hungary's Istvan Komàromy discovered a method of
creating moulds from eyes. It was the first time that contact lenses could be
made according to the shape of the eye. New plastics, polymethyl
methacrylate (PMMA or Perspex/Plexiglas). Plastic, which is difficult to
breakable, is resistant to scratchiness and easy to manufacture, transformed
the contact lens industry in a new chapter.
In 1960, Bausch and Lomb started to use hydrogel and brought it to a brand-
new higher level, developing a perfected casting procedure that generated lens
surfaces which are consistent and with a mass-production process. In 1998,
Ciba Vision, introducted silicone hydrogels and provided it an extraordinarily
oxygen permeability in a very high degree (Key, 2007). Over the next 25 years,
hard and soft contact lenses continued to advance, particularly in terms of
oxygen permeability, which means breath degree of our eyes.


5

Results and Discussion
Mode of operation
Contact lenses are made to capture and reflect light in such a way that they
correct the way eyes see it. They bend light so that it focuses on the retina,
where collected is data by receptors of vision and then this data is transferred
to the most important organ in our body, brain. Once in place, the contact
focuses light to a single focal point on the retina (Eyeconic Blog, 2018). It looks
like a magnifying glass. The light that enters your eyes is fine-tuned and
focused by it.
Light rays focus too early on myopic eyes, forming a focal point in front of the
retina rather than immediately on it. Myopia is treated by contact lenses and
spectacles that diverge light beams, reducing the concentrating strength.
(Heiting, 2020).
The eyes of hyperopic people do not have enough focusing ability, and light
rays do not create a focal point by the time they reach the retina. Hyperopia is
corrected via contact lenses and spectacles that converge light rays, increasing
focusing strength. (Heiting, 2020).
Technical attributes
When it comes to the contact lenses manufacturing, choosing the material is
quite essential and the polymeric material is required to be suitable.
Therefore, there is a large group number of possibilities to do it. In addition,
several types of polymerisation methods to generate the same polymer, such
as radical polymerisation, catalytic polymerisation and their derivatives, must
be considered. The polymerisation circumstances can be changed within this to
generate the same polymer with varied properties. Apart from a great
6

biocompatibility, the material must be capable for phases to manufacture such
as synthesis, inspection, and packaging (Musgrave and Fang, 2019). Also,
demands of users must be considered by several general features, such as
comfort, wear time, handling, cost, and vision specifications (Musgrave and
Fang, 2019). Finally, some of the most key features such as wettability, lens
thickness, mechanical properties, oxygen permeability, water content, wear
time, handling and comfort from a materials science perspective that contact
lenses must contain when designing them (Huang, 2020).
Ingredients
In the current market, there are two major varieties of contact lenses which
are soft contact lenses and rigid contact lenses.
soft contact lenses
Hydrogel and silicone hydrogel are two common substances used to make soft
contact lenses. The properties of these materials can have an impact on the
health of eyes and overall contact lens experience.
Hydrogel lenses
Because of its water content, hydrogel material is very flexible. In comparison
to stiff contact lenses, hydrogel contact lenses feel soft and comforting on the
wearer. The most notable distinction between hydrogels and other polymers is
that hydrogels have a hydrophilic structure that can absorb a substantial
amount of water, allowing for biocompatibility and customised mechanical
strength (Ahmed, 2015).
Several essential properties such as water content, oxygen permeability,
mechanical qualities, and Optical transparency play an important role when it
7

comes to the contact lens (Efron, 2010). Soft contact lenses' optical and
mechanical qualities are all influenced by these factors.
Poly (hydroxyethyl methacrylate), or pHEMA is the first and most extensively
used material to manufacture the traditional hydrogel contact lenses. Due to
the hydroxyl group at the end of the pHEMA, this polymer has a special
property which is hydrophilic.
According to Efron and Brennan (1988), HEMA soft lenses have a water
content in vivo of about 40%, and eye dryness is relevant to this water content.
HEMA copolymers were then added to increase the water content. N-vinyl
pyrrolidone is the most utilised (NVP). Because the NVP molecule's amide
structure may establish hydrogen bonds with water, the gel matrix contains
more water. HEMA/NVP copolymers are a type of HEMA/NVP copolymer (All
Answers Ltd. 2018).
NVP can also copolymerize with hydrophobic monomers like methyl
methacrylate (MMA). When compared to pHEMA, their copolymer MMA/NVP
can obtain a higher water content while maintaining the same level of
flexibility (Hosaka et al., 1980). However, this copolymer has evident flaws,
such as a higher amount of bacterium deposit (Miller and Ahearn, 1987) and
protein build-up (Hosaka et al., 1983).
Silicone hydrogel lenses
Compared to regular hydrogel lenses, this newer version allows more oxygen
to reach the eye (approximately 5 times more oxygen). Unlike hydrogel lenses,
silicone hydrogel lenses' oxygen permeability is determined by the amount of
silicone utilised rather than the water content (Huang, 2020).
8

Silicone is a flexible gel-like material that is frequently utilised in medical
devices. The wettability of the first silicone hydrogel lenses was improved by
coating them. Wettability has an impact on contact lens comfort and dryness
(Huang, 2020).
Silicon rubber with a greater oxygen permeability was created by Gaylord.
Tris(trimethylsiloxy)-methacryloxy-propyl silane (TRIS) was the monomer (All
Answers Ltd. 2018). CooperVision incorporates wettability into its silicone
hydrogel lenses' chemistry, eliminating the requirement for surface treatments
or internal wetting agents. These materials are referred to as third-generation
materials (all three generations will be explained later in the appendix)
because they use the most recent technology to create wettability in silicone
hydrogel polymers (Huang, 2020).
Rigid contact lenses
PMMA (poly (methyl methacrylate)) is a polymer commonly utilised in hard
lens manufacturing. It is an excellent lens material because it is transparent
and easy to work with. However, immediately after rigid lenses became
popular, practitioners observed that if oxygen permeability of PMMA lenses is
limited, it would interfere the normal function of ours eye, resulting in dryness,
redness, and corneal oedema (All Answers Ltd. 2018).
Manufacture
soft contact lenses
Cast moulding
Cast moulding is the most common method of manufacturing soft lenses. The
mould has two sections: anterior and posterior. The material is poured into the
posterior mould and subsequently it would be capped with the anterior mould,
9

giving a curved shape to a lens (All Answers Ltd. 2018). The lens gets harden
when the mould moves along the production line. After that, ultraviolet light
initiates this polymerisation. Finally, the lens is filled with contact lens solution
and ready to package after a thorough check.
Spin casting
Spin casting is a centrifugal force approach to produce contact lenses instead
of mechanical cutting. In a rotating mould, the liquid material is injected into it
(Menicon, 2017). By utilising the heat or UV light, the polymerisation reaction
is slowly get started when the mould rotates at a steady rate. It is worth to
mention that the base curve and the front curve are shaped differently. The
former one is by centrifugal force but the later one by the mould. Before the
final package, lens has to be hydrated again to keep its elasticity when it is
removed from the mould. This method has a low manual cost but turns out a
high throughout (All Answers Ltd. 2018). It is not commonly used yet due to
the difficulty of design and modelling of the equipment.
Rigid contact lenses
Because rigid lenses are comprised of hard, glassy materials, lathe cutting is
the most typical method of production. The front and back surfaces of the lens
are created by cutting polymer buttons with a lathing tool. Rigid lenses, on the
other hand, can often be personalised with engraving. Computers control
these procedures, allowing manufacturers to make changes as needed.
Polishing is a key stage in rigid lens production, and comprehensive checks are
required. The finished product might be dry or packaged in solutions (All
Answers Ltd. 2018).
Future development of the product
10

The future of contact lenses is bright. A variety of technologies are influencing
the future of contact lenses, with some already demonstrating their potential
in late-stage development projects and commercially accessible devices.
Contact lenses could deliver drugs thereby making it able to detect, treat, and
monitor full body medical conditions. Diabetes is one of them. Technology
even suggests that contact lenses could be used to deliver information
displays. Some suggest contact lenses also potentially have the capability
prevent the myopia among young teenagers (Revolutionary Future Uses of
Contact Lenses, 2014). Furthermore, contact lenses could eventually have the
property of diagnosing diseases. Cancer, hypertension, and Alzheimer's all
therefore can be early detected so as to improving our health (Waterloo,
2021).

Reference
Ahmed, E.M. (2015). Hydrogel: Preparation, characterization, and applications: A review.
Journal of Advanced Research, [online] 6(2), pp.105–121. doi:10.1016/j.jare.2013.07.006.
All Answers Ltd. (2018). Contact Lens: Materials and Manufacturing Processes. [online].
Available from: https://ukdiss.com/examples/contact-lens-development.php?vref=1
[Accessed 8 May 2022].
Efron, N. (2010). Obituary—Rigid contact lenses. Contact Lens and Anterior Eye, 33(5),
pp.245–252. doi:10.1016/j.clae.2010.06.009.
Efron, N. and Brennan, N.A. (1988). A survey of wearers of low water content hydrogel
contact lenses. Clinical and Experimental Optometry, 71(3), pp.86–90. doi:10.1111/j.1444-
0938.1988.tb06554.x.
11

Eyeconic Blog. (2018). How Do Contact Lenses Work? [online] Available at:
https://blog.eyeconic.com/tips-tricks-and-tech/how-contact-lenses-work-contacts-
101.html#:~:text=Contact%20lenses%20work%20by%20bending. [Accessed 5 May 2022]
Heiting, G. (2020). How do contact lenses work? [online] All About Vision. Available at:
https://www.allaboutvision.com/en-au/contact-lenses/faq/how-contacts-work. [Accessed 5
May 2022].
Hosaka, S., Ozawa, H., Tanzawa, H., Ishida, H., Yoshimura, K., Momose, T., Magatani, H. and
Nakajima, A. (1983). Analysis of deposits on high water content contact lenses. Journal of
Biomedical Materials Research, 17(2), pp.261–274. doi:10.1002/jbm.820170205.
Hosaka, S., Yamada, A., Tanzawa, H., Momose, T., Magatani, H. and Nakajima, A. (1980).
Mechanical properties of the soft contact lens of poly(methyl methacrylate-N-
vinylpyrrolidone). Journal of Biomedical Materials Research, 14(5), pp.557–566.
doi:10.1002/jbm.820140503.
Huang, M. ed., (2020). Contact Lenses 101, Part 1: Contact Lens Materials. [online] Cooper
Vision. Available at: https://coopervision.com/practitioner/ecp-viewpoints/technicians-and-
staff%E2%80%8C/contact-lenses-101-part-1-contact-lens-materials [Accessed 7 May 2022].
Key, J.E. (2007). Development of contact lenses and their worldwide use. Eye & Contact
Lens, [online] 33(6 Pt 2), pp.343–345; discussion 362-363.
doi:10.1097/ICL.0b013e318157c230.
Lockwood, A.L.A. (2021). History Of Contact Lenses. [online] Feel good contacts. Available
at: https://www.feelgoodcontacts.com/eye-care-hub/the-history-of-contact-lenses.
[Accessed 2 May 2022].
Menicon. (2017). Miru 1 day Menicon Flat Pack [Online]. Available:
https://www.menicon.com/pro/our-products/soft-lens/1day-miru/ [Accessed 8 May 2022].
Miller, M.J. and Ahearn, D.G. (1987). Adherence of Pseudomonas aeruginosa to hydrophilic
contact lenses and other substrata. Journal of Clinical Microbiology, 25(8), pp.1392–1397.
doi:10.1128/jcm.25.8.1392-1397.1987.
12

Musgrave, C. and Fang, F., (2019). Contact Lens Materials: A Materials Science Perspective.
Materials, 12(2), p.261.
Revolutionary Future Uses of Contact Lenses. (2014). Optometry and Vision Science, 91(10),
p.1157. doi:10.1097/opx.0000000000000386.
Waterloo, U. of (2021). The future of contact lenses is bright. [online] ScienceBlog.com.
Available at: https://scienceblog.com/524253/the-future-of-contact-lenses-is-bright/
[Accessed 9 May 2022].
1800contacts.com. (2022). [online] Available at:
https://www.1800contacts.com/eyesociety/da-vinci-to-disposable-a-history-of-contact-
lenses. [Accessed 2 May 2022]



Appendix
Table 1. Common Contact lens materials
Rigid contact lens PMMA
Soft contact lens Hydrogel lenses Silicone hydrogel
lenses
pHEMA TRIS-DMA
HEMA-MMA PDMS-HEMA
HEMA-NVP
*PMMA- poly methyl methacrylate, pHEMA-poly (hydroxyethyl methacrylate), DMA-dimethyl
methacrylate, HEMA-hydroxy ethyl methacrylate, NVP-N-vinyl pyrrolidone, TRIS-3-
[tris(trimethylsiloxy)silyl]propyl methacrylate, MMA-methyl methacrylate, PDMS—poly dimethyl
siloxane

13

Table 2. Developments (three generations) in Silicone Hydrogel Materials
First generation lenses Balafilcon A
Lotrafilcon A
Second generation lenses Senofilcon A
Lotrafilcon B
Senofilcon C
Third generation lenses Comfilcon A
Asmofilcon A
Enfilcon A
Samfilicone A