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Update on Refractive Surgery and Femtosecond Laser

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Update on Refractive Surgery and Femtosecond Laser - Dr James Beatty

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Update on Refractive Surgery and Femtosecond Laser

  1. 1. Update on Refractive Surgery and Femtosecond Laser Dr James Beatty
  2. 2. Introduction • Refractive fellowship course Zurich, Switzerland • Prof Michael Mrochen and Prof Seiler at the IROC eye center in Zurich, Switzerland
  3. 3. Presentation outline • Refractive surgery options • Patient evaluation • Diagnostic and surgical equipment • Latest laser treatment ablation profiles • Cases
  4. 4. Goals of refractive surgery • Independence of glasses • Gain in quality of life • …..to satisfy the patients’ expectation
  5. 5. Modalities • Corneal procedures – Lasik – PRK – Epi-lasik • Intra-ocular procedures – Phakic IOL – Multifocal IOLs – Refractive lens exchage
  6. 6. Lasik
  7. 7. PRK
  8. 8. Epilasik
  9. 9. Phakic IOL
  10. 10. Phakic ICL
  11. 11. Multifocal IOL
  12. 12. Clear lens exchange
  13. 13. Evaluation • Motivation – Personality, Job, Life style • Psychological profile – Unrealistic expectations • Education and counseling – Transparency (technique, complications… ) – Confidence – Presbyopia
  14. 14. Indications • Motivated patient • >18 years • Rx stable for at least 1-2 years • No ocular pathology or eye rubbing risk
  15. 15. Examination • Degree of correction – Myopia –12 – Hypermetropia +5 – Astigmatism • Corneal keratometry – Average K > 48.5 or < 40 • Corneal vascularization
  16. 16. Examination • Corneal thickness – Usually >500um, Leave > 250um • Ablation depth – Ablation depth approx 20um per diopter – Example: Pt with refraction of –6D corneal thickness = 520um flap = 160um 6 D ablation = 120um residual bed = 520 – (160 +120) = 240 um
  17. 17. Examination • Pupil size – In the dark – Caution >8mm • Surgical exposure – Small deep palpebral fissure • Dry eye – Consider pre and post operative treatment
  18. 18. Risks / Complications - Over-correction & under-corrections. Less15% and it depends on the initial refraction. - The higher the refractive error is the greater the chance of having under-correction. - Enhancements may be done three months or later if the cornea is thick enough (10%) - Infection. -Corneal flap complications.
  19. 19. Risks / Complications - DLK deep lamellar keratitis or Sands of Sahara - Epithelial ingrowth - Night glare. This is normally present for the first few months. Depends on the optical zone and pupil size. - Haze. - Corneal ectasia
  20. 20. Equipment • Diagnostic and treatment planning – Topography – Aberometry • Surgical – Microkeratomes – Femtosecond lasers – Excimer lasers
  21. 21. Corneal topography • To detect irregular astigmatim • Keratoconus and subclinical (formfrust) • Pellucid marginal degeneration • Detect stability of corneal warpage from contact lenses • Stability of cornea post lasik
  22. 22. Corneal topography • Method of capture very NB • Irregular surface from dry eyes • Extrapolation of data • Provides laser ablation profiles for topography guided treatments
  23. 23. Corneal topography • 2 main types – Placido disc (Orbscan) – Scheimpflug photography (Pentacam)
  24. 24. Aberrations and aberometers
  25. 25. Aberometry • Wavefront analysis • Measures the overall performance of the eye • Measures aberations of the eye • Provides laser treatment profiles for wavefront guided treatments • Needs to be very accurate
  26. 26. Laser treatments • Wavefront optimized • Q-value adjusted ablation • Wavefront guided • Topography guided
  27. 27. Laser treatments • Wavefront optimized – Maintain the physiological condition – Reduce the number of aberations that are created by the laser – especially spherical aberations
  28. 28. Laser treatments • Q-value adjusted ablations – Hyperprolate cornea for enhanced monovision – Increase depth of focus by increased prolateness of the cornea (add +1D) – In addition myopia in the non-dominant eye (- 0.75D to –1.5D) – Dominant eye plano
  29. 29. Laser treatments
  30. 30. Laser treatments • Wavefront guided – Improve the optical quality for the total eye – Needs to be very accurate and reproducible
  31. 31. Laser treatments
  32. 32. Laser treatments
  33. 33. Laser treatments • Topography guided – Therapeutic treatments for vision enhancements – Unable to measure total aberrations of the eye, or not reproducible – Corneal based problems • Scars • Retreatments
  34. 34. Wavefront-guided 5% Topography-guided 5% Custom Q 10% Wavefront OptimizedTM 80%
  35. 35. Microkeratomes
  36. 36. Microkeratomes • Use a blade to cut corneal flap • Suction ring • Microkeratome • Manual and automated • Some variability in flap thickness
  37. 37. Femtosecond lasers • Significant advance in the field of refractive surgery • Focusable infrared laser similar to the Nd-YAG used for posterior capsulotomy • Ultra fast firing in the femtosecond range (100 times 10 power of 15) • Causes photodisruption…..tissue vaporization… gas bubble formation in the stroma • Thermal damage to adjacent tissue only 1um
  38. 38. Femtosecond lasers • Software is able to create different flap shapes and edges • Control flap size, thickness, hinge location • More predictable • Less complications
  39. 39. Excimer lasers • FS 200.mpg
  40. 40. Excimer lasers
  41. 41. Case 1 • 40 year old women • Rigid gas permeable CL for 15 yrs (now intolerant) • Graves/thyroid eye disease
  42. 42. Case 1 • Wearing – OD -3.25/-1 @ 168 VA 20/20 – OS -2/-0.5 @ 35 VA20/20 • Manifest – OD –3.5/-1.25 @ 160 VA20/20 – OS –2.5/-0.75 @ 45 VA20/20 • Cycloplegic – OD –3.5/-1.5 @165 – OS –2.5/-0.5 @ 35 • Keratometry – OD 41 @170 and 43 @80 – OS 42.12 @35 and 43.75 @ 125
  43. 43. Case 1 • Pachmetry – OD 548 um – OS 552 um • Topography – Regular astigmatism OU consistent with refraction – Increased aberrations (spherical and coma) • Scotpic pupils – OD 6.9mm – OS 6.8mm
  44. 44. Case 1 • Examination – Acne rosacea – Blepharitis – Mild proptosis – Dry eyes
  45. 45. Case 1 • Hard contact lenses • Dry eyes • Diffuse lamellar keratitis • Wavefront guided treatment
  46. 46. Case 2 • 32 year old • Soft contacts for 10 years • No problems
  47. 47. Case 2• Wearing – OD -4/-0.5 @180 VA 20/25+ – OS –4/-0.75 @ 180 VA20/30 • Manifest – OD –4.25/-0.5 @180 VA 20/20 – OS –4.5/-0.75@175 VA 20/20 • Cycloplegic – OD –4.25/-0.5 @180 – OS –4.5/-0.75 @180 • Keratometry – OD 43 @180 / 43.5 @90 – OS 42.5@ 180 / 43.5 @90
  48. 48. Case 2 • Pachymetry – OD 475um – OS 480um • Topography – Regular bow tie • Scotopic pupil – OD 6.5mm – OS 6.5mm
  49. 49. Case 2 • Examination – Normal – Thin corneas ? PRK – Orbscan shows posterior elevation of 47um in the R and 49um in the L. – What are the risk factors for keratoconus and formfrust keratoconus?
  50. 50. Case 2 • Risk factors for keratoconus – Changing prescription – Inferior steepening and superior flattening – Posterior elevation of cornea – High K’s (>47.2) – High astigmatism – Asymetry between superior and inferior corneal power – Corneal thickness
  51. 51. Case 3 • 45 year old business executive • Never worn glasses • Good VA till 2 years ago when he started using reading gls • Now uses them for driving as well • Otherwise in good health
  52. 52. Case 3 • Wearing – +2 readers VA 20/60 OU • Manifest – OD +2 VA 20/40 – OS +2 VA 20/40 • Cycloplegic – OD +4.75 VA 20/20 – OS +4.5 VA 20/20 • Keratometry – OD 45.5 @ 180 /45.75 @90 – OS 45.5 @180 /45.5 @90
  53. 53. Case 3 • Pachymetry – OD 555 um – OS 547 um • Topography – Mild inferior steepening, post elevations normal • Scotopic pupil – OD 5.2 mm – OS 5.2 mm
  54. 54. Case 3 • Examination – Corneal diameter of 10.3mm – Otherwise normal
  55. 55. Case 3 • Discussion – Uncorrected hyperopia – Most of these pts believe they have excellent vision despite poor VA – They try to go without gls for as long as they can – Often unhappy after correction unless you correct prebyopia as well
  56. 56. Case 3 • So what procedure? – Cycloplegic refraction falls within range of hyperopic Lasik, but: • decreased accuracy and unable to do monovision • Keratometry too steep after treatment • Corneal diameter too small. Hyperopic lasik requires large flap and treatment zone. • PRK may avoid these problems
  57. 57. Case 3 • Advised against Lasik • Full gls correction was not tolerated • Progressive increase with contact lenses was tolerated better and reading gls over • In the end he gave up on this because he said his vision was worse after removing the contacts • Clear lens extractions were recommended with restore multifocal IOLs

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