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MANUFACTURING
METHODS OF SOFT
CONTACT LENSES
Mithali Kamat-Paranjape M. Optom,
To view more presentations and articles, vi...
Spin Casting
• Liquid polymer is injected
into the spinning mold
• Centripetal force forms
aspheric base curve
• Front cur...
Spin Casting
• Periphery of the lens is
buffed and polished to
produce a smooth surface
• Lens is then hydrated in a
steri...
Spin casting
1. Lens geometry is
determined by spin speed
and volume of material
injected
2. Spin speed also determines
th...
Advantages of Spincasting
Features
1. Tapered edge profiles
and smooth surfaces
2. Back aspherical surface
of the lens mat...
Lathe Cutting
• Diameter of the button is
12 to 15mm
• Thickness is 4.5mm
To view more presentations and articles, visit w...
Lathe Cutting- Posterior Surface
• Button is ground
to the required
diameter
• Base curve is cut
• Peripheral curves
are c...
Lathe Cutting
Lathe Cutting
• Polishing should be done
for less than 50secs
• Over polishing can cause
– Heating and warpage
– Change of...
BC Polishing
Lathe Cutting- Anterior Surface
• Button is blocked on
same curvature tool.
• Wax used is
– Water soluble for RGP
lenses
–...
Lathe Cutting- Anterior Surface
Lathe Cutting- Anterior Surface
• The curvature of the front surface is decided
depends on the power to be generated
– For...
Lathe Cutting- Anterior Surface
To view more presentations and articles, visit www.eyenirvaan.com
Lathe Cutting- Anterior Polishing
Lathe Cutting- Lens Hydration
Lathe Cutting
• After hydration lens is rinsed under running
saline water
• Quality control check
– Surface defects
– Base...
To view more presentations and articles, visit www.eyenirvaan.com
Lathe Cutting
Advantages
• Lathe-cut lens are usually
thicker (when compared
with spincast lenses)
→relatively easier to h...
Cast Molding
– mold production
– lens casting
– lens hydration,
– lens inspection/packaging
To view more presentations and...
Forms base curve
of lens
Forms front curve
of lens
Cast Molding
To view more presentations and articles, visit www.eyenirv...
Cast Molding- manufacturing process
1.Anterior mold is injected with liquid monomer
2.Anterior mold is then capped with th...
Advantages of Cast Molding
• Produce finished lenses without the
need to polish
• Produce a high quality lens at a lower
c...
Reverse Process III
• Combines the best of spin casting and lathe
cutting
• Anterior surface → spun cast
• Posterior surfa...
Lightstream Process
Lightstream Process
Polymer liquid put into
concave mold
Metal mask to stop UV light from curing
the polymer that gets bel...
Lightstream Process
Non touching
molds
Lens
Mask
Edge formation
Ultraviolet Light
Polymer not cured by
UV light is washed
...
Coloured Contact Lenses
• Made by cast
molding
• Pigments
embedded in the
middle layer
• Lenses are much
thinner and
smoot...
To view more presentations and articles, visit www.eyenirvaan.com
Manufacturing methods of soft contact lens - presentation at www.eyenirvaan.com
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Manufacturing methods of soft contact lens - presentation at www.eyenirvaan.com

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Manufacturing methods of soft contact lens - presentation at www.eyenirvaan.com

  1. 1. MANUFACTURING METHODS OF SOFT CONTACT LENSES Mithali Kamat-Paranjape M. Optom, To view more presentations and articles, visit www.eyenirvaan.com
  2. 2. Spin Casting • Liquid polymer is injected into the spinning mold • Centripetal force forms aspheric base curve • Front curve formed by curvature of mold • Ultraviolet light is applied to cure or solidify the lens. To view more presentations and articles, visit www.eyenirvaan.com
  3. 3. Spin Casting • Periphery of the lens is buffed and polished to produce a smooth surface • Lens is then hydrated in a sterile water bath – A polymacon (HEMA) lens absorbs about 38.6% of its weight in water, and expands in volume approximately 12%. To view more presentations and articles, visit www.eyenirvaan.com
  4. 4. Spin casting 1. Lens geometry is determined by spin speed and volume of material injected 2. Spin speed also determines the final lens power 3. Center thickness of the lens is determined by the volume of polymer injected into the mold To view more presentations and articles, visit www.eyenirvaan.com
  5. 5. Advantages of Spincasting Features 1. Tapered edge profiles and smooth surfaces 2. Back aspherical surface of the lens matches well with the aspheric profile of the cornea 3. Has only one base curve Benefits 1. Enhanced comfort during lens wear 2. Minimal lens movement on the eye yet acceptable tear film dynamics 3. Easy to fit To view more presentations and articles, visit www.eyenirvaan.com
  6. 6. Lathe Cutting • Diameter of the button is 12 to 15mm • Thickness is 4.5mm To view more presentations and articles, visit www.eyenirvaan.com
  7. 7. Lathe Cutting- Posterior Surface • Button is ground to the required diameter • Base curve is cut • Peripheral curves are cut • Thickness is reduced to 2.5mm To view more presentations and articles, visit www.eyenirvaan.com
  8. 8. Lathe Cutting
  9. 9. Lathe Cutting • Polishing should be done for less than 50secs • Over polishing can cause – Heating and warpage – Change of curvature – Non wettable surface • The semi-finished button is then cleaned in an ultrasonic bath To view more presentations and articles, visit www.eyenirvaan.com
  10. 10. BC Polishing
  11. 11. Lathe Cutting- Anterior Surface • Button is blocked on same curvature tool. • Wax used is – Water soluble for RGP lenses – Petroleum/tinner soluble for soft CL To view more presentations and articles, visit www.eyenirvaan.com
  12. 12. Lathe Cutting- Anterior Surface
  13. 13. Lathe Cutting- Anterior Surface • The curvature of the front surface is decided depends on the power to be generated – For -3.00D, if Base curve is 7.5, the front surface should be 7.9 – For high powers, lenticular anterior surfaces are cut with peripheral anterior curves To view more presentations and articles, visit www.eyenirvaan.com
  14. 14. Lathe Cutting- Anterior Surface To view more presentations and articles, visit www.eyenirvaan.com
  15. 15. Lathe Cutting- Anterior Polishing
  16. 16. Lathe Cutting- Lens Hydration
  17. 17. Lathe Cutting • After hydration lens is rinsed under running saline water • Quality control check – Surface defects – Base curve – BVP • Sealed in sterile vials. • Autoclaved To view more presentations and articles, visit www.eyenirvaan.com
  18. 18. To view more presentations and articles, visit www.eyenirvaan.com
  19. 19. Lathe Cutting Advantages • Lathe-cut lens are usually thicker (when compared with spincast lenses) →relatively easier to handle • Lathe-cut lens has a better lens movement and centration when compared with spin-cast lens Disadvantages • time consuming and labor intensive → expensive • difficult to reproduce since each lens is individually made
  20. 20. Cast Molding – mold production – lens casting – lens hydration, – lens inspection/packaging To view more presentations and articles, visit www.eyenirvaan.com
  21. 21. Forms base curve of lens Forms front curve of lens Cast Molding To view more presentations and articles, visit www.eyenirvaan.com
  22. 22. Cast Molding- manufacturing process 1.Anterior mold is injected with liquid monomer 2.Anterior mold is then capped with the posterior mold. 3.The capped assembly then travels through a series of ultra-violet lights where the liquid monomers become harden To view more presentations and articles, visit www.eyenirvaan.com
  23. 23. Advantages of Cast Molding • Produce finished lenses without the need to polish • Produce a high quality lens at a lower cost than any other process. • Have very consistent edges and smooth surface characteristics
  24. 24. Reverse Process III • Combines the best of spin casting and lathe cutting • Anterior surface → spun cast • Posterior surface → lathe cut – Eg: Optima 38 To view more presentations and articles, visit www.eyenirvaan.com
  25. 25. Lightstream Process
  26. 26. Lightstream Process Polymer liquid put into concave mold Metal mask to stop UV light from curing the polymer that gets below the mask UV light
  27. 27. Lightstream Process Non touching molds Lens Mask Edge formation Ultraviolet Light Polymer not cured by UV light is washed away in a later process
  28. 28. Coloured Contact Lenses • Made by cast molding • Pigments embedded in the middle layer • Lenses are much thinner and smoother To view more presentations and articles, visit www.eyenirvaan.com
  29. 29. To view more presentations and articles, visit www.eyenirvaan.com

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