The Science of Vision Correction Dean Dornic, MD (Mr. Science) Laser Eye Center of Carolina
A 60 Year History of LASIK <ul>1949 Columbian Ophthalmologist Barraquer describes a lamellar corneal procedure to correct ...
ALK the Predecessor to LASIK <ul><li>A microkeratome is used to create a flap and to remove a disc of corneal tissue </li>...
Birth of LASIK: Introduction of Excimer Laser Results in Name Change <ul><li>1983: First journal article describing the us...
1989: First patent for the LASIK procedure </li></ul>
Improvements in Technology Have Resulted in Improvements in Outcomes <ul><li>Lower risk of complications (decentered ablat...
Higher likelihood of spectacle independence </li></ul>
Higher Order Aberrations <ul><li>Introduction of aberrations reduce visual quality and decrease patient satisfaction
Spherical aberration a result of oblate cornea </li></ul>
Significant Refinements: Ablation <ul><li>Wider treatment zones
Flying spot
Pupil tracker
Wavefront-guided and optimized treatments
Iris registration </li></ul>
Wavefront Technology <ul><li>Wavefront-guided procedures utilize a wavefront analyzer to correct higher order aberrations
No analyzer necessary for wavefront-optimized procedures </li></ul>
Wavefront Technology Benefits are More than Just Theoretical <ul><li>Wavefront-guided procedures have greatest rates of 20...
WFG procedures have lowest enhancement and night-vision problems </li></ul>
Night Vision Satisfaction after CustomVue <ul><li>Patient satisfaction with night vision increases after WFG procedures
Ratio of improved vs worsened night vision is 4:1 </li></ul>
Important Points for Patients Wavefront Guided is not equivalent to Wavefront Optimized WFG Procedures can correct HOAs WF...
The LASIK Flap <ul><li>Serves to speed recovery
Lessens likelihood of haze, regression and infection
Most common source of complication </li></ul>
Significant Refinements in Flap Creation/ Improved Safety Elimination of perforation risk Elimination of exposed gears Eli...
Cornea Flap Creation with Microkeratome <ul><li>Suction ring exposes cornea.
Oscillating blade a set distance below metal plate creates flap
Variability in amount of exposed cornea results in variability of flap parameters </li></ul>
Flap Creation with IntraLase Femtosecond Laser <ul><li>Cleavage  plane created by photodisruption and resultant gas bubble...
 
Downside of IntraLase (FS30) Increased Expense Increased Time Flaps More Difficult to Lift Risk of Flap Tears Transient Li...
Ziemer LDV Portable Familiar Technique Fast Able to Create Thin Flaps
Ziemer Complications Free Flaps Small Irregular Flaps
Result of Ziemer Complications Small Irregular Flaps Managed with Immediate PRK Both Cases Required Enhancements For Quali...
IntraLase FS60 Less OBL Delay Faster Procedure Time No Free Flaps No Small Irregular Flaps
Head to Head Comparison of Complications: First 150 Cases Most Previous Papers Attempt to Compare Complication Rates Utili...
Comparison of Complications First 150 Cases <ul><li>IntraLase </li></ul><ul><ul><li>1 incomplete flap
1 slipped flap </li></ul></ul><ul><li>Ziemer </li></ul><ul><ul><li>2 free flaps
2 small irregular flaps
1 slipped flap </li></ul></ul>
My Ziemer Complication Rate vs Pietela et al  J Ref Surg <ul>My Results (150 cases) <li>2 Free Flaps  1.3%
2 Irregular Flaps  1.3%
1 Flap Displacement  0.7% </li></ul><ul>Pietela (787 cases) <li>21 Free Flaps  2.7%
16 Decentered 2.0%
10 Pseudobuttonholes  1.3%
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Science of Vision Correction

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A lecture describing the evolution of LASIK and differences in LASIK technology.

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Science of Vision Correction

  1. 1. The Science of Vision Correction Dean Dornic, MD (Mr. Science) Laser Eye Center of Carolina
  2. 2. A 60 Year History of LASIK <ul>1949 Columbian Ophthalmologist Barraquer describes a lamellar corneal procedure to correct refractive error </ul>
  3. 3. ALK the Predecessor to LASIK <ul><li>A microkeratome is used to create a flap and to remove a disc of corneal tissue </li></ul>
  4. 4. Birth of LASIK: Introduction of Excimer Laser Results in Name Change <ul><li>1983: First journal article describing the use of the Excimer laser to treat refractive error
  5. 5. 1989: First patent for the LASIK procedure </li></ul>
  6. 6. Improvements in Technology Have Resulted in Improvements in Outcomes <ul><li>Lower risk of complications (decentered ablations, asymmetric ablations, quality of vision issues)
  7. 7. Higher likelihood of spectacle independence </li></ul>
  8. 8. Higher Order Aberrations <ul><li>Introduction of aberrations reduce visual quality and decrease patient satisfaction
  9. 9. Spherical aberration a result of oblate cornea </li></ul>
  10. 10. Significant Refinements: Ablation <ul><li>Wider treatment zones
  11. 11. Flying spot
  12. 12. Pupil tracker
  13. 13. Wavefront-guided and optimized treatments
  14. 14. Iris registration </li></ul>
  15. 15. Wavefront Technology <ul><li>Wavefront-guided procedures utilize a wavefront analyzer to correct higher order aberrations
  16. 16. No analyzer necessary for wavefront-optimized procedures </li></ul>
  17. 17. Wavefront Technology Benefits are More than Just Theoretical <ul><li>Wavefront-guided procedures have greatest rates of 20/20 or better
  18. 18. WFG procedures have lowest enhancement and night-vision problems </li></ul>
  19. 19. Night Vision Satisfaction after CustomVue <ul><li>Patient satisfaction with night vision increases after WFG procedures
  20. 20. Ratio of improved vs worsened night vision is 4:1 </li></ul>
  21. 21. Important Points for Patients Wavefront Guided is not equivalent to Wavefront Optimized WFG Procedures can correct HOAs WFO Procedures strive to limit new HOAs You can achieve good results with conventional LASIK WFG need not be reserved for patients with high HOAs WFG Procedures give the Opportunity for Improved BVA WFG Procedures Give the Best Night Vision Why would you not want a WFG procedure?
  22. 22. The LASIK Flap <ul><li>Serves to speed recovery
  23. 23. Lessens likelihood of haze, regression and infection
  24. 24. Most common source of complication </li></ul>
  25. 25. Significant Refinements in Flap Creation/ Improved Safety Elimination of perforation risk Elimination of exposed gears Elimination of on-eye assembly Vacuum meters/ audible tones Increased customization Femtosecond laser flap creation Sidecuts
  26. 26. Cornea Flap Creation with Microkeratome <ul><li>Suction ring exposes cornea.
  27. 27. Oscillating blade a set distance below metal plate creates flap
  28. 28. Variability in amount of exposed cornea results in variability of flap parameters </li></ul>
  29. 29. Flap Creation with IntraLase Femtosecond Laser <ul><li>Cleavage plane created by photodisruption and resultant gas bubbles released a set distance below cornea surface applanated by glass plate </li></ul>
  30. 31. Downside of IntraLase (FS30) Increased Expense Increased Time Flaps More Difficult to Lift Risk of Flap Tears Transient Light Sensitivity Syndrome
  31. 32. Ziemer LDV Portable Familiar Technique Fast Able to Create Thin Flaps
  32. 33. Ziemer Complications Free Flaps Small Irregular Flaps
  33. 34. Result of Ziemer Complications Small Irregular Flaps Managed with Immediate PRK Both Cases Required Enhancements For Quality of Vision Issues
  34. 35. IntraLase FS60 Less OBL Delay Faster Procedure Time No Free Flaps No Small Irregular Flaps
  35. 36. Head to Head Comparison of Complications: First 150 Cases Most Previous Papers Attempt to Compare Complication Rates Utilized Different Surgeons Same Surgeon 98 cases IntraLase FS30 150 cases Ziemer LDV 52 Cases IntraLase FS60 added to IntraLase Group for Equal Sample Size
  36. 37. Comparison of Complications First 150 Cases <ul><li>IntraLase </li></ul><ul><ul><li>1 incomplete flap
  37. 38. 1 slipped flap </li></ul></ul><ul><li>Ziemer </li></ul><ul><ul><li>2 free flaps
  38. 39. 2 small irregular flaps
  39. 40. 1 slipped flap </li></ul></ul>
  40. 41. My Ziemer Complication Rate vs Pietela et al J Ref Surg <ul>My Results (150 cases) <li>2 Free Flaps 1.3%
  41. 42. 2 Irregular Flaps 1.3%
  42. 43. 1 Flap Displacement 0.7% </li></ul><ul>Pietela (787 cases) <li>21 Free Flaps 2.7%
  43. 44. 16 Decentered 2.0%
  44. 45. 10 Pseudobuttonholes 1.3%
  45. 46. 2 Split Flaps 0.3%
  46. 47. 3 Flap Displacements 0.4% </li></ul>
  47. 48. IntraLase Flap Creation <ul><li>3-Dimensional flap
  48. 49. 2-steps with side cut added last
  49. 50. Flap creation visible throughout </li></ul>
  50. 51. IntraLase Flap Creation <ul><li>Diameter and location of flap can be altered before proceeding
  51. 52. Side cut is created last as a seperate stage </li></ul>
  52. 53. IntraLase Control Panel <ul><li>Allows for perfectly centered flap
  53. 54. True customization
  54. 55. Unlimited flap diameters and flap thicknesses
  55. 56. Last minute adjustments </li></ul>
  56. 57. IntraLase Flap <ul><li>Flap creation visible throughout procedure
  57. 58. Because surface not affected, flap can still be salvaged if there is interruption </li></ul>
  58. 59. Ziemer Flap Creation <ul><li>Single Plane “Cut” Similar to Microkeratome
  59. 60. Initial Applanation and Alignment Visible
  60. 61. Creation of Flap Not Visible to Surgeon </li></ul>
  61. 62. Ziemer Flap Creation <ul><li>Diameter of Ziemer flap dependent on area applanated
  62. 63. Diameter affected by corneal curvature
  63. 64. Sidecut performed simultaneously with the rest of the flap </li></ul>
  64. 65. Loss of Suction with IntraLase Loss of suction visible. Procedure can be halted and resumed.
  65. 66. Loss of Suction with Ziemer <ul><li>Loss of full applanation before flap creation is initiated results in a free flap
  66. 67. Loss of full applanation after flap initiation results in smaller, irregular flap </li></ul>
  67. 68. Suction Loss is Not Rare The Consequences of Suction Loss is Different for 2 Reasons: 1. Surgeon is “Blind” to Flap Creation When the Ziemer Laser is Used: Loss of Full Applanation May not Be Apparent 2. The Side Cut is a Second Seperate Stage When the IntraLase Laser is Used: This Allows for Recovery/Salvage of the Case When Suction is Lost
  68. 69. Prevention of Complications Proper and Adequate Suction/Applanation Separate Side-Cut With “Manhole” Configuration Should Reduce Slipped Flaps Separate Side Cut Allows for Salvage/Resumation When Suction Lost Full Visualization/Proper Intervention Should Limit Incomplete or Free Flaps
  69. 70. Ziemer Pros and Cons <ul>Pros <li>Portable
  70. 71. No OBL
  71. 72. Technique Familiar
  72. 73. Fast
  73. 74. Flaps Easy to Lift </li></ul><ul>Cons <li>Limited Customization
  74. 75. Diameter Influenced by Corneal Shape
  75. 76. Single Plane Flaps
  76. 77. Unable to Visualize
  77. 78. Interuption of Case Usually Results in Cancellation
  78. 79. Higher Complication Rate </li></ul>
  79. 80. IntraLase Pros and Cons <ul>Pros <li>Customization
  80. 81. Better “Fine Tuning”
  81. 82. Manhole Configuration
  82. 83. Full Visualization
  83. 84. Free and Irregular Flaps are Rare
  84. 85. Interruption Rarely Results in Cancellation </li></ul><ul>Cons <li>More Cumbersome
  85. 86. OBL Can Slow Down Case
  86. 87. Not as Portable
  87. 88. More Uncomfortable For Patient
  88. 89. Higher Rate of Subconjunctival Hemorrhage </li></ul>
  89. 90. Summary Femtosecond Laser Technology Can Produce Thinner, More Consistent Flaps The IntraLase Laser Allows for Better Surgeon Control and Is Much Less Likely to Result in Complications, Postponement or Conversion to PRK than the Ziemer LDV Laser
  90. 91. Z-LASIK Flap Architecture <ul><li>Single plane, exactly as that created by a microkeratome
  91. 92. All complications seen with microkeratome can be seen with Z-LASIK </li></ul>
  92. 93. IntraLase Flap Architecure <ul><li>Manhole configuration
  93. 94. No free flaps
  94. 95. No Small/ irregular flaps
  95. 96. Second chance possible
  96. 97. More secure </li></ul>
  97. 98. Electron Micrograph Comparison <ul><li>IntraLase Flap
  98. 99. Z-LASIK Flap </li></ul>
  99. 100. Bonus Advantage <ul><li>Stromal bed smoother with IntraLase </li></ul>
  100. 101. IntraLase Flap Creation
  101. 102. Monitor View
  102. 103. Conclusion <ul><li>Safest way to make a flap is IntraLase
  103. 104. Best vision achievable is with CustomVue
  104. 105. Chief advantage of Z-LASIK is cost
  105. 106. Military does not perform Z-LASIK. Statements such as “technology approved by the military” are, at the very least, misleading
  106. 107. All “custom procedures” are not equivalent
  107. 108. All “all-laser” procedures are not equivalent </li></ul>
  108. 109. Need for New Terminology <ul><li>The precedence for a change in terminology is evidenced by change from ALK to LASIK
  109. 110. There is a need to differentiate iLASIK and similar technologies from LASIK and Z-LASIK
  110. 111. Side effect / complication statistics from earlier technologies are not applicable to iLASIK
  111. 112. Consumers need to be able to compare “apples to apples” </li></ul>

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