Update on Refractive Surgery and Femtosecond Laser

3,402
-1

Published on

Update on Refractive Surgery and Femtosecond Laser - Dr James Beatty

Published in: Health & Medicine
0 Comments
11 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
3,402
On Slideshare
0
From Embeds
0
Number of Embeds
3
Actions
Shares
0
Downloads
0
Comments
0
Likes
11
Embeds 0
No embeds

No notes for slide
  • No microkeratome Thinner corneas
  • Reading, night driving Risk free surgry does not exisit Quality of va is not just va …….glare, gosting, contrast, decreased near Need for re treatment
  • ker
  • Large pupil….custom ablation Femtosecond Plugs, tear suplements, cyclosporin
  • Infection less than conatct lens
  • To detect
  • Until recently unable to meausre higher order aberations
  • undercorrected
  • Needs to be out of hard contacts for long enough to ensure corneal stab if in doubt or diff between refract and topo wait Dry eye pretreat Treat bleph with doxy and scrubs, increased DLK Wave front appropriate because consistency and higher aberations
  • B/w 40 and 50 suspicios for keratokonus > 50 is keratokonus
  • 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

    ×