Visionary Ophthalmology Lectures Series 12, May 22nd 2011

2. From freezing to photoablation The evolution of lasik J. Alberto Martinez, M.D. Visionary Ophthalmology May 12, 2011

4. OUTLINE Incisional refractive surgery Lamellar refractive surgery Non-excimer laser lamellar refractive surgery Excimer assisted lamellar refractive surgery LASIK in the US Femptosecond role in LASIK Future of Refractive surgery

5. Martinez’ classification of refractive surgery Corneal procedures Conjuntival procedures Scleral procedures Anterior chamber procedures Iris/pupil procedures? Sulcus procedures Crystalline lens procedures Globe shortening procedures

6. Corneal procedures Incisional procedures: RK, AK, LRI Surface reshaping: PRK ( PTK), CK orthokeratology Stromal reshaping: LASIK, Intralasestromal ablation Augmentation procedures: Corneal inlays, Intacts

7. Radial Keratotomy Tsutomu Sato of Japan, 1933: 40-45 endothelial side cuts: Corneal edema

8. Cornea: RK, AK/LRI RK reshapes the cornea by relaxing steep meridians Advantages: Quick, inexpensive Disadvantages: Inaccurate, variable

9. Radial Keratotomy Early 1970s, Dr. Yenaliev, Durnev and Fyodorov: External incisions only Dr Fyodorov And Dr. Leo Boris introduced RK in the United States in 1978 Incisional refractive surgery still plays a role in some procedures, mostly LRI’s or limbal relaxing incisions for astigmatic correction after cataract surgery

10. Incisional refractive surgery (IRS) Outdated because: Unpredictability Limited range of effect (minor myopia, up to four diopters) Better options (lamellar) Still however used today as LRI, limbal relaxing incisions for multifocal IOLs

11. Dr. Luis Ruiz, RK innovator

12. CK® Thermokeratoplasty: technique that uses RF energy to heat and reshape the cornea

13. Lamellar Refractive surgery Conceived and developed By Dr. Jose Barraquer Bogota, Colombia. Voted as the most influential ophthalmologist of the 20th century

14. Ley de Espesores – Law of Thicknes

15. Keratomilieusis

16. The Microkeratome

17. Automated Lamellar Keratoplasty, ALK

18. ExcimerLaser Developed at IBM in 1976 to etch microchips First introduced by Stephen Trokel in 1983 LASIK was essentially a procedure already performed in Bogota by Dr. Barraquer. Excimerlaser only made it more accurate

19. EXCIMER LASER

20. Excimer Laser in ALK 1990 LASIK was born as the “flap and Zap” Dr. Steven Slade 1995 LASIK approved by the FDA for commercial use 1999 use of wavefront technology 2008 LASIK approved for Navy Pilots and astronauts

21. ALK + Excimer = LASIK

22. First Generation Excimer lasers

23. Second Generation Excimer Lasers

24. Wavescan: Wavefront scan

25. Customized Ablations

26. WAVEFRONT GUIDED VS.WAVEFRONT OPTIMIZED

27. WavefrontGUIDEDTreatment Wavefront measurement ( lower order aberrations: Defocus (sphere) and Astigmatism (cylinder) To measure Higher order aberrrations Need Dilated pupils ( correspond to 6-7mmOZ)

28. WavefrontGUIDEDTreatment A wavefrontrefration with small pupils Plus larger diameter treatments= High technology autorefractionfollowed by standard excimer laser treatment Optical aberrations increase with age, mostly associated with lenticular changes, thus not stable over time.

29. Wavefront Optimized excimerlasers: Latest generation of lasers ALLEGRETTO WAVE® LASER FEATURES

30. Wavefront Optimized Latest lasers: Smaller scanning spots But smaller: more rapid repetition rate to achieve a given amount of tissue removal Increased rate of laser firing causes higher temperature at treatment site.

32. ALLEGRETTO WAVE® Eye-Q laser prevents this by only allowing every fifth pulse to overlap with a previous one.

33. Optimal temporal and spacial shot distribution is required to minimize potential thermal load Optimized shot distribution ensure that only every 5th pulse is allowed to overlap the first. This helps minimize thermal build up and provides adequate time for plume evacuation. 1. Mrochen M et al. J Cataract Refract Surg. 2009;35:363-373. Thermal Optimized Shot Distribution

34. Eye tracking Must have PRECISE eye tracking to follow eye during abaltion Precision limited by LATENCY Time between eye recognition of movement and redirection of scanning spot With smaller spots LATENCY must be minimized

36. The ALLEGRETTO WAVE® Eye-Q laser tracker can:

37. Center on natural pupils from 1.5 mm to 8 mm diameter

38. Track pupil movements at 400 Hz

39. Acquires the image, processes it and verifies the position of eye before releasing the pulse.The 400-Hz eye tracking system verifies the eye position and automatically corrects shot placement for natural eye movement. 1. Chalita MR, Krueger RR. In: Albert & Jakobiec’s Principles and Practices in Ophthalmology. 3rd ed. Philadelphia, PA: Saunders W B Co; 2008:1041-1049. Active, High-speed Eye Tracking

40. Wavefront Optimized Designed to avoid induction of spherical aberration Earlier lasers and techniques less predictable with spherical aberration Goal is to reshape cornea to a theoretically superior profile Translate clinical data to precise tissue removal

42. The angle of incidence approaches the critical angle in the periphery and becomes partially absorbed

43. The result is less fluence and thus sub-optimal ablationNormal Ablation When beam shape broadens in the periphery, fluency can fall below the ablation threshold (≈45 uJ/cm2). Wavefront Optimized® algorithms maintain the natural pre-op corneal curvature by compensating for this effect. The algorithm delivers more shots to the periphery, to produce a refractive treatment with minimal increases in spherical aberration. 1. Seiler T, Koller T. In: Albert & Jakobiec’s Principles and Practices in Ophthalmology. 3rd ed. Philadelphia, PA: Saunders W B Co; 2008:981-985.

44. The Femtosecond laser

45. Corneal reshaping: Intralase PresbyLASIK: Ablation within the stroma without disrupting the surface. Great promise . Developed by Dr. Luis A. Ruiz of Bogota, Colombia

47. IDEAL IOL

48. Thank you for your attention! Contact information: J. Alberto Martinez MD www.myeyesurgeon.com jalbertom@comcast.net