Uploaded May 2017 | Updated September 2026, 2 days ago
By Michael Shiu, Colin Kim, and Kevin Allman
Silicone hydrogels are used for the manufacture of soft contact lenses. In today’s society, which is a highly visual world full of electronic screens, hyperopia (farsightedness) is a growing problem among individuals, especially as they get older. Hyperopia is caused by parallel light rays not bending sufficiently to focus by the time they reach the retina due to weaknesses in the relaxed lens system. Thus, there is a need to improve the technology of contact lenses.
A physical property of silicone hydrogels is the ability to refract light; so convex silicone hydrogel lenses can be used to increase the refractive power of the eye to correct the effects of farsightedness. It is, therefore, important that the material used to manufacture contact lenses is able to do this without distortion and maintain clarity. Silicone hydrogels have sufficient elasticity that allows them to conform to slightly different eye surface shapes depending on the person wearing the lenses, maximizing comfort and effectiveness. A key issue with contact lense materials is their oxygen permeability. Oxygen permeability is important because it allows the cornea to receive adequate amounts of oxygen to prevent hypoxia of the eye through the diffusion of oxygen gas through the actual contact lens. When passed through silicone, the oxygen permeability increases. On the other side, wettability, which is measured by the angle of the contact lens, is important because a complete wetting will permit a thick coverage of the tear film, a smooth recovery of the tear layer after the eyes are closed, and adequate visual acuity. This leads to a longer duration of wearing the lenses. This is a limitation to silicone hydrogel lenses, for its hydrophobic nature produces a poorly wettable surface. However, through the complementary use of wetting agents such as eye drops, the limitation becomes negligible. Another limitation is the lipid depositions during wear, which leads to blurry vision and contact lenses. Compared to conventional lenses, the presence of silicone leads to a much greater lipid deposition.
Overall, silicone hydrogel contact lenses are a breakthrough technology, increasing oxygen permeability while maintaining wettability to improve comfort. Because silicone hydrogel lenses are fairly new to the market, the costs of these lenses are higher on average, but the costs are expected to decline over time with increased availability. More research needs to be conducted to improve the issue of wettability. Currently, there are products that help re-hydrate the lens to reduce issues with discomfort and lipid deposits, but changes to the structure and composition of silicone hydrogels could eliminate the need for such extraneous products that only add to the total cost of using this kind of contact lens. Moreover, the 3 features (Process/Structure/Properties) of the MSE triangle will be discussed throughout the video.
Images/Videos Used
1) youtube.com/watch?v=Av1ZiN9P01s
2) opticalvisionresources.com/wp-content/uploads/2013/11/WB-1930contact_lense.jpg
3) topconsumerreviews.com/contact-lenses/new-images/header-contact-lenses.jpg
4) blog.eyedo.in/wp-content/uploads/2015/09/sillicon.jpg
5) youtube.com/watch?v=JoxuBcg7S1o
6) upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Vinylpyrrolidon.svg/100px-Vinylpyrrolidon.svg.png
7) sigmaaldrich.com/content/dam/sigma-aldrich/structure4/061/mfcd00002651.eps/_jcr_content/renditions/mfcd00002651-medium.png
8) upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Polyhydroxyethylmethacrylate_structural.svg/160px-Polyhydroxyethylmethacrylate_structural.svg.png
en.wikipedia.org/wiki/Silicone_rubber#/media/File:Pdms.png
9) youtube.com/watch?v=Kas5v8isarw
10) google.com/search?q=wettability&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwinstny1aTTAhWEJCYKHQ11CQwQ_AUIBygC&biw=1163&bih=537#imgrc=H_P6AgnahnNrWM:
11) tekra.com/resources/tek-tip-white-paper/tek-tip-hydrophilic-vs-hydrophobic-coatings
12) clspectrum.com/issues/2002/march-2002/silicone-hydrogel-material-and-surface-properties
google.com/search?q=infected+eye+from+contact+lenses&rlz=1C1CHBF_enUS710US711&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjQz8CdhqPTAhUF6yYKHVh7Df0Q_AUICCgB&biw=1280&bih=591#imgrc=9YM4T87Yb_ht7M
13) allaboutvision.com/contacts/contact_lenses.htm#materials
14) clspectrum.com/archive/2002/march/26b.jpg
Research Sources
docs.google.com/document/d/1GDPFO3BJQQb0sly3vr1snuPG-Af2ZeQnvTpqJ3yBpoE/edit?usp=sharing
By Michael Shiu, Colin Kim, and Kevin Allman
Silicone hydrogels are used for the manufacture of soft contact lenses. In today’s society, which is a highly visual world full of electronic screens, hyperopia (farsightedness) is a growing problem among individuals, especially as they get older. Hyperopia is caused by parallel light rays not bending sufficiently to focus by the time they reach the retina due to weaknesses in the relaxed lens system. Thus, there is a need to improve the technology of contact lenses.
A physical property of silicone hydrogels is the ability to refract light; so convex silicone hydrogel lenses can be used to increase the refractive power of the eye to correct the effects of farsightedness. It is, therefore, important that the material used to manufacture contact lenses is able to do this without distortion and maintain clarity. Silicone hydrogels have sufficient elasticity that allows them to conform to slightly different eye surface shapes depending on the person wearing the lenses, maximizing comfort and effectiveness. A key issue with contact lense materials is their oxygen permeability. Oxygen permeability is important because it allows the cornea to receive adequate amounts of oxygen to prevent hypoxia of the eye through the diffusion of oxygen gas through the actual contact lens. When passed through silicone, the oxygen permeability increases. On the other side, wettability, which is measured by the angle of the contact lens, is important because a complete wetting will permit a thick coverage of the tear film, a smooth recovery of the tear layer after the eyes are closed, and adequate visual acuity. This leads to a longer duration of wearing the lenses. This is a limitation to silicone hydrogel lenses, for its hydrophobic nature produces a poorly wettable surface. However, through the complementary use of wetting agents such as eye drops, the limitation becomes negligible. Another limitation is the lipid depositions during wear, which leads to blurry vision and contact lenses. Compared to conventional lenses, the presence of silicone leads to a much greater lipid deposition.
Overall, silicone hydrogel contact lenses are a breakthrough technology, increasing oxygen permeability while maintaining wettability to improve comfort. Because silicone hydrogel lenses are fairly new to the market, the costs of these lenses are higher on average, but the costs are expected to decline over time with increased availability. More research needs to be conducted to improve the issue of wettability. Currently, there are products that help re-hydrate the lens to reduce issues with discomfort and lipid deposits, but changes to the structure and composition of silicone hydrogels could eliminate the need for such extraneous products that only add to the total cost of using this kind of contact lens. Moreover, the 3 features (Process/Structure/Properties) of the MSE triangle will be discussed throughout the video.
Images/Videos Used
1) youtube.com/watch?v=Av1ZiN9P01s
2) opticalvisionresources.com/wp-content/uploads/2013/11/WB-1930contact_lense.jpg
3) topconsumerreviews.com/contact-lenses/new-images/header-contact-lenses.jpg
4) blog.eyedo.in/wp-content/uploads/2015/09/sillicon.jpg
5) youtube.com/watch?v=JoxuBcg7S1o
6) upload.wikimedia.org/wikipedia/commons/thumb/d/d2/Vinylpyrrolidon.svg/100px-Vinylpyrrolidon.svg.png
7) sigmaaldrich.com/content/dam/sigma-aldrich/structure4/061/mfcd00002651.eps/_jcr_content/renditions/mfcd00002651-medium.png
8) upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Polyhydroxyethylmethacrylate_structural.svg/160px-Polyhydroxyethylmethacrylate_structural.svg.png
en.wikipedia.org/wiki/Silicone_rubber#/media/File:Pdms.png
9) youtube.com/watch?v=Kas5v8isarw
10) google.com/search?q=wettability&espv=2&source=lnms&tbm=isch&sa=X&ved=0ahUKEwinstny1aTTAhWEJCYKHQ11CQwQ_AUIBygC&biw=1163&bih=537#imgrc=H_P6AgnahnNrWM:
11) tekra.com/resources/tek-tip-white-paper/tek-tip-hydrophilic-vs-hydrophobic-coatings
12) clspectrum.com/issues/2002/march-2002/silicone-hydrogel-material-and-surface-properties
google.com/search?q=infected+eye+from+contact+lenses&rlz=1C1CHBF_enUS710US711&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjQz8CdhqPTAhUF6yYKHVh7Df0Q_AUICCgB&biw=1280&bih=591#imgrc=9YM4T87Yb_ht7M
13) allaboutvision.com/contacts/contact_lenses.htm#materials
14) clspectrum.com/archive/2002/march/26b.jpg
Research Sources
docs.google.com/document/d/1GDPFO3BJQQb0sly3vr1snuPG-Af2ZeQnvTpqJ3yBpoE/edit?usp=sharing
