ibruce/courses/ee3ba3_2011/ee... · 2 . 3 . 4 •what are contact lenses? •why contacts and not...

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bull What are contact lenses

bull Why contacts and not glasses

bull What are they made of and how have they changed

bull What kind of contacts

bull How are they made

bull Biocompatibility with contact lenses

bull What are the current issues with contact lenses

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bull Comfort

6

1508 1936

1887 1949

1971

1959 first contact lens were and it covered the entire eyes ndash Scleral Contact Lenses

Leonardo da Vinci introduced the concept of contact lenses

1999

Plastic lenses were developed

Plastic contact lenses that made are to cover only the eyersquos cornea - Corneal Lenses (Hard lenses)

Hydrophilic gel introduced

Soft lenses were introduced

First Silicone Hydrogel Contact Lenses were introduced

7

bull Sclearal Lens (1887)

ndash Too heavy

bull Plastic Lens (1936)

ndash Still covered entire eye

bull Corneal Lens (1949)

ndash Unable to wear for long periods of time

bull Non Gas Permeable Lens

ndash PMMA (polymethyl methacrylate)

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bull Visual Acuity bull Biocompatibility

ndash Tear film ndash Hydrophilic ndash Biofilm resistance

bull Wetabilityoxygen permeability ndash At least semi-permeable measured in (DKL)

bull Size amp gravity weight ndash Lightweight ndash Appropriate modulus of elasticity

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bull Manufacturing process ndash Ensure the lens are highly pure ndash Every lens should undergo quality testing

bull Affordable price ndash Buy at a reasonable cost if made the lens cheaply and

efficiently

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bull Also known as lsquohardrsquo lenses

bull Moderately hydrophobic

bull Typical oxygen permeability of 05 DK

bull Good outdoor weathering properties and rigidity

bull Canrsquot be used for more than 8 hours at a time

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bull HEMA substituted with monomers glycerol methacrylate (GMA)

ndash shows a higher resistance biofilm formation

bull oxygen permeability of about 15-25 Barrers (DK)

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bull High bond strength

bull Resists temperature extremes weathering aging oxidation moisture many chemicals and ultraviolet radiation

bull High Breathability

bull hydrophobic

13

The modified version of Henryrsquos law for polymers below their glass transition temperature

Fickrsquos law for glassy polymers is

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bull Hard lenses (RGP)

bull Soft lenses

bull Extended-wear

bull Disposable

bull Cosmetic lens (color lens)

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bull Rigid Gas Permeable lens (RGP) bull Methacryloxypropyl tris(trimethysiloxy silane)

(TRIS) co polymerized with MMA ndash Results in oxygen permeability of silicone ndash Doped with fluoromethacrylates

bull Methacrylic acid (MAA) added to increase lens wetability

bull consist of an amorphous three dimensional polymer matrix (typically a MMA derivative) that is below its glass transition temperature

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bull First soft lenses were made with poly hydroxyethyl methacrylate (pHEMA)

bull range from low oxygen permeability to high oxygen permeability

bull Consists of a three dimensional amorphous network with cross-links that is above its glass transition temperature

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bull Oxygen permeability of the lens is proportional to the amount of water in the lens

bull As the water content is increased the polymers lose their strength

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RGP Lenses Soft Lenses

Visibility Clear and sharp Less sharp

Durability Long Short in relation to other lenses

Comfort Rigid Comfortable for long wear

Adaptation Long period Short period

Care Personal time extensive Short personal time duration

Biofilm resistance Highly resistant Collects deposits

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bull Made of polymethyl methacrylate (PMMA)

bull Covered the entire of cornea

bull very stiff and has a high elasticity modulus

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bull Latest development in soft contact lens materials

bull DK of 600 Barres

bull Retains the comfort and resistance of wetability and biofilm

bull a greater propensity to attract and collect lipid deposits

bull Better overall eye health

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bull Oxygen permeability forms an inverse relationship with water content

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bull Injection molding

bull Lathe Cutting

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25

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bull Process in which molten polymer is

forced under high pressure into a mold cavity

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bull Optical qualities

bull Proper fitting

bull Constant blinking

bull Varying the thickness and shape

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bull Proper fitting



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bull Oxygen permeability

bull Hydrophilic

bull Angle of contact

bull Size

bull Thickness

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bull Microbial Keratitis ndash corneal infection

bull Acanthamoeba Keratitis ndash Due to improper lens handling and poor hygiene

bull Ulcers ndash Due to prolonged wearing of contact lenses and

chemical injury

bull Hypoxia ndash Inadequate oxygen supply due to sleeping with lens

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chemical injury


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bull Comfort VS effectiveness

bull Hard lens VS soft lens

bull Amount of care needed

bull Health disorder

bull Adaptability of eyes

bull Do not do make your eyes healthier

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bull Material is always the subject to study for contact lenses

bull investigating different chemical recipes that may give the plastic more desirable characteristics - siloxane

bull Investigation new polymers for scleral lenses

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bull Many advances have been made to reduce the health impacts of contact lenses on the eye

bull Ideal lens would have moderate visual acuity comfortable extended wear high oxygen permeability no biological impact resistance to outdoor conditions and little care required

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bull http3bpblogspotcom_akDwxMm7VvIS_sKSSFc35IAAAAAAAABa0tA_7itY0KCQs

1600reading+glassesjpg

bull httpwwwdaviddarlinginfoimagesgas_permeable_contact_lensjpg

bull httpiehowcomimagesa04bcnjlaser-eye-surgery-work-200X200jpg

bull httpwwwabbaeyecarecomimagesclear-visionjpg

bull httpwwwtradekoreacomproductscontact_lenshtml

bull httpchoosingacompanynamecomcontacts-for-stigmatismphp

bull httpwwwyouknowitcomcontact-lens-blogindexphpbad-romance-contact-lenses

bull httpmoneycnncomgalleries2008fortune0805galleryprivate_equity_power_listfortune5html

bull httpwwwcomparestorepricescoukhealth-and-beautybausch-and--lomb-bausch-and-lomb-boston-advance-cleanerasp

bull httpflatpackmicrowavepizzacouklens-scleral-frontjpg

bull httpwwwcorriganopticianscoukassets174CorriganPic_15jpg

bull httplens-logiccomproductionphp

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bull httpwwweyetopicscomarticles171Contact-Lenses-vs-Eyeglasseshtml

bull httpcontact-lens-reviewtoptenreviewscomwho-shouldn-t-wear-contact-lenseshtml

bull httpwwwallaboutvisioncomcontactsfaqwhen-inventedhtm

bull httpezinearticlescomHave-You-Ever-Wondered-How-Do-Contact-Lenses-Workampid=55135

bull httpovidsptxovidcomlibaccesslibmcmastercasp-322bovidwebcgiampS=AHPGFPOBFIDDHFJINCDLCEJCPFPNAA00ampLink+Set=Ssh157c17csl_10

bull httpwwwsubstechcomdokuwikidokuphpid=injection_molding_of_polymers

bull httpwwwengbuffaloeduCoursesce4352001ZGuContact_LensContactLensReporthtm

bull httpwww1-contact-lenses-consumer-guidecomabout-rgphtml

bull httpwwwmadehowcomVolume-2Contact-Lenshtml

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bull Comfort

6

1508 1936

1887 1949

1971



1999






7


ndash Too heavy







8





9



efficiently

10






11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




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20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



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bull Proper fitting



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bull Hydrophilic


bull Size

bull Thickness

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chemical injury


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chemical injury


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3

4








5

bull Comfort

6

1508 1936

1887 1949

1971



1999






7


ndash Too heavy







8





9



efficiently

10






11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


32







33




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35














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5

bull Comfort

6

1508 1936

1887 1949

1971



1999






7


ndash Too heavy







8





9



efficiently

10






11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


32







33




34



35














36










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5

bull Comfort

6

1508 1936

1887 1949

1971



1999






7


ndash Too heavy







8





9



efficiently

10






11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


32







33




34



35














36










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bull Comfort

6

1508 1936

1887 1949

1971



1999






7


ndash Too heavy







8





9



efficiently

10






11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


32







33




34



35














36










37

1508 1936

1887 1949

1971



1999






7


ndash Too heavy







8





9



efficiently

10






11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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ndash Too heavy







8





9



efficiently

10






11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


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efficiently

10






11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


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34



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efficiently

10






11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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36










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11




12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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12




bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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bull hydrophobic

13



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


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34



35














36










37



14


bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


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34



35














36










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bull Soft lenses

bull Extended-wear

bull Disposable


15





16




17



18








19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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19




20






21


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bull Lathe Cutting

24

25

26



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bull Proper fitting



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bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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20






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bull Lathe Cutting

24

25

26



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bull Proper fitting



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bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

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chemical injury


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chemical injury


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20






21


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bull Lathe Cutting

24

25

26



27


bull Proper fitting



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bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

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chemical injury


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chemical injury


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19




20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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20






21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


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33




34



35














36










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21


22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



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bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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33




34



35














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22


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


32







33




34



35














36










37


23


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


32







33




34



35














36










37


bull Lathe Cutting

24

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


32







33




34



35














36










37

25

26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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34



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26



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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33




34



35














36










37



27


bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


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33




34



35














36










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bull Proper fitting



28


bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


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33




34



35














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bull Proper fitting



29


bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


31




chemical injury


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33




34



35














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bull Hydrophilic


bull Size

bull Thickness

30




chemical injury


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chemical injury


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chemical injury


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chemical injury


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chemical injury


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ibruce/courses/ee3ba3_2011/ee... · 2 . 3 . 4 •what are contact lenses? •why contacts and not...

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