Unit 1

Question 1

beggining Leonardo DaVinci

Answer 1

-Described a method of directly altering corneal power
–By immersing the eyeball in a bowl of water
◦ Controversial topic

Question 2

beggining Rene Descartes

Answer 2

◦ Fluid filled tube on the eye
◦ While impractical, the principle of directly neutralizing corneal power is consistent with the principles underlying modern contact lens design
* Contact lens name origin
◦ In “contact” with the eye

Question 3

beginning Thomas Young

Answer 3

◦ Constructed a “fluid-filled eyecup”
◦ Similar system to that used by Descartes
◦ He did not intend the device to be used for correction of refractive errors

Question 4

1800- * Sir John Herschel

Answer 4

◦ Proposed ‘taking a mould of the cornea and impressing it on some transparent medium’

Question 5

1800- * F.A. Muller

Answer 5

◦ Manufacturers of prosthetic eyes
◦ Described the fitting of a partially transparent shell of thin clear blown glass to a patient

Question 6

1800- * Eugene Kalt (French ophthalmologist)

Answer 6

Fit thin glass shells for keratoconus patients and obtained significant improvement in vision

Question 7

1800- * August Muller

Answer 7

Credit for fitting the first powered contact lens
◦ Described the correction of his own high myopia with a contact lens
-Lens was made by optical engineer, Karl Otto Himmler
-First manufacturer of optically ground contact lenses

Question 8

early 1900- * Carl Zeiss Company

Answer 8

Applied for a patent proposing the manufacture of contact lenses from ‘cellon, celluloid, or similar organic substance…’
◦ First to cut lenses from moulds
◦ Diagnostic lenses (trial lens set)

Question 9

early 1900- * Joseph Dallos

Answer 9

◦ Refined fitting and moulding techniques
◦ Went on to develop techniques for taking impressions of the human eye

Question 10

1930- * PMMA (polymethyl methacrylate)

Answer 10

◦ Moulded or lathe cut
◦ Difficult to break, lighter than glass
◦ NOT oxygen permeable

Question 11

1930- * William Feinbloom

Answer 11

◦ Combined PMMA with glass (centre)
* Large glass contact lens

Question 12

• Dallos (1946)

Answer 12

◦ Fenestration (putting little holes, helps w/ oxygen permeability)

Question 13

1940- * Large plastic contact lenses

Answer 13

Contact Lenses (1948)

Question 14

• Kevin Tuohy (1948)

Answer 14

-Credited with the first PMMA corneal contact lens
-Error during the lathing of a PMMA scleral lens (haptic and corneal portions separated)

Question 15

• Tanaka (1950)

Answer 15

◦ PMMA corneal lens in Japan
◦ Developed a machine to make lenses
◦ Precursor to Menicon contact lens company

Question 16

• Joseph Soper (1950s and 60s)

Answer 16

◦ Smaller diameter corneal lenses
◦ Soper keratoconus lens

Question 17

1960s and 1970s- * Norman Gaylord

Answer 17

Incorporated silicone into the basic PMMA structure
◦ Patented oxygen permeable lenses (gas permeable lenses)

Question 18

1960 and 1970- * Otto Wichterle

Answer 18

◦ Unable to attract support…Wichterle conducted experiments in his own home
-Developed the spin-casting technique
◦ Invented soft contact lenses
◦ HEMA material (hydroxyethyl methacrylate)

Question 19

1960-1970- * Bausch & Lomb

Answer 19

◦ Acquired the patent to develop soft contact lenses commercially in the USA
◦ Introduced soft lenses into the world market in 1972

Question 20

1980s- * Toric soft contact lenses

Answer 20

correct astigmatism

Question 21

1980- Silicone lenses

Answer 21

◦ Oxygen permeability
◦ Extended wear

Question 22

1980 CL

Answer 22

• Bifocal soft contact lenses
• • Coloured contact lenses
• Disposable contact lenses (daily)

Question 23

1980- disposable lenses

Answer 23

◦ In the early days, patients would typically use the same pair of lenses…until they couldn’t

Question 24

what did Klas Nilsson of Gorthenburd, sweden do??

Answer 24

convinced patients of the benefits of 6-month replacement frequency

Question 25

Gothenburg study’

Answer 25

proved the benefits of regular lens replacement

Question 26

◦ ‘Danalens’

Answer 26

low-cost, multiple individual lens packs
-First truly disposable lens
-Purchased by Johnson & Johnson in 1984
-Acuvue lens!

Question 27

1990- * Daily disposable contact lenses

Answer 27

◦ ‘Premier’ daily disposable launched in the UK in 1994
◦ Johnson & Johnson released the ‘1-Day Acuvue’ around the same time
◦ CIBA Vision entered the daily disposable lens market in 1997 with ‘Dailies’
-More disposable options

Question 28

• Silicone Hydrogel Lenses (1998)

Answer 28

◦ Focus Night & Day (CIBA Vision)
◦ Purevision (Bausch & Lomb)
* The introduction of these lenses is considered to be the most significant advance in contact lens material technology since the development of HEMA by Wichterle

Question 29

The future

Answer 29

• Convenience and ocular health benefits of daily disposable lenses are likely to increase in popularity
• Silicone hydrogels are set to continue as the main material from which lenses are fabricated
  ◦ However, the possibility of a new lens material should not be discounted
• Likely to be used increasing for the correction of presbyopia (refractive error for middle-aged & older adults to see things up close)
• Extended wear is unlikely to break through the ‘glass ceiling’

Question 30

more of the future

Answer 30

• Anti-myopia designs
• Anti-infective and anti-inflammatory lenses (medications released into the eye)
• Glucose monitoring
• Intraocular pressure measurement
• Digital information acquisition and display (e.g. a contact lens version of Google Glass)

Question 31

Soft Lens Manufacture

Answer 31

• Lathe cutting
• Spin casting
• Cast moulding

Question 32

Lathe cutting

Answer 32

• More expensive
• Custom lenses
  ◦ High spherical and/or toric powers, keratoconus
• Polymer button
• Diamond tipped tool
  ◦ Back surface lathed first
  ◦ Front surface lathed
• Inspection -> hydration -> re-inspection
• Inserted into vial
• Autoclaved to effect sterilization

Question 33

Spin casting

Answer 33

• Stainless steel convex tool produced
• Plastic concave mould formed
• Liquid plastic monomer added to spinning concave mould
• UV radiation to initiate lens polymerization
• Edge polished
• Inspection -> hydration -> inspection
• Inserted into blister pack containing saline
• Autoclaved

Question 34

Cast Moulding

Answer 34

• Stainless steel concave and convex tools produced
• Plastic concave and convex moulds formed
• Liquid plastic monomer added to concave plastic mould
• Plastic moulds clipped together
• Contact lens forms in between moulds
• UV radiation to initiate lens polymerization
• Inspection -> hydration -> inspection
• Inserted into blister pack containing saline
• Autoclaved

Question 35

Cast Moulding

Answer 35

• Most common
  ◦ Very consistent production
  ◦ Do not need to polish
  ◦ Lower cost
  ◦ Efficient
• Also called injection moulding