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LASIK Surgery is Safe in the Long-Term
1. LASIK is safe in the long run; looking back at 50 years of lamellar corneal surgery Dan Z Reinstein MD MA(Cantab) FRCSC FRCOphth 1,2,3,4 Timothy J Archer, MA(Oxon), DipCompSci(Cantab) 1 1. London Vision Clinic, London, UK 2. St. Thomas’ Hospital - Kings College, London, UK 3. Weill Medical College of Cornell University, New York, USA 4. Centre Hospitalier National d’Ophtalmologie, (Pr. Laroche) , Paris, France
2. What do we know about the long-term safety of LASIK?
3. National Institute for Clinical Excellence – UK “ guidance on the use of new and existing medicines, treatments and procedures within the NHS”
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6. Published Long-Term PRK Outcomes - Myopia Stability Safety 136 eyes Mean SE: -11.40 D Summit Technology UV 200 Optical zone: 4 mm No ectasia
7. Published Long-Term LASIK Outcomes - Myopia Stability Safety 33 eyes Mean SE: -11.40 D Schwind Keratom I Chiron ALK 130 Optical zone: 5.5 or 6 No ectasia
8. Published Long-Term LASIK Outcomes - Hyperopia 125 eyes Mean SE: +3.84 D Chiron Technolas Keracor 117C Chiron Corneal Shaper 160 Optical zone: 5.5 mm Stability Safety 5% lost 2 lines No ectasia
22. Keratomileusis Early Cohort vs Modern LASIK Keratomileusis LASIK Range of myopia Up to -27.00 D 86% above -7.01 D Rarely treated above -10.00 D Screening for keratoconus None, keratoconus unknown Topography unavailable Awareness of keratoconus Astigmatism, steep & thin corneas Front & back surface topography Future advances – epithelial thickness profiles, corneal stiffness Depth of keratectomy Deep resection: 300-350 µm in all eyes Original microkeratome: inaccurate & imprecise Microkeratomes more accurate & precise Thin flaps commonly used: avg 110 µm Accurate measurement of corneal thickness and residual stromal bed Low myopia - low ablation depths Ectasia 2.8% from the original cohort ~ 0.06% (more later)
23. Keratomileusis Early Cohort vs Modern LASIK Keratomileusis LASIK Range of myopia Up to -27.00 D 86% above -7.01 D Rarely treated above -10.00 D Screening for keratoconus None, keratoconus unknown Topography unavailable Awareness of keratoconus Astigmatism, steep & thin corneas Front & back surface topography Future advances – epithelial thickness profiles, corneal stiffness Depth of keratectomy Deep resection: 300-350 µm in all eyes Original microkeratome: inaccurate & imprecise Microkeratomes more accurate & precise Thin flaps commonly used: avg 110 µm Accurate measurement of corneal thickness and residual stromal bed Low myopia - low ablation depths Ectasia 2.8% from the original cohort ~ 0.06% (more later)
24. What else do we know about the long-term safety of LASIK? Screening for Keratoconus
36. METHODS: Theory of Early Keratoconus Artemis KC B-Scan Normal In early keratoconus, epithelial thinning masks the cone Earliest epithelial changes occurring in KC are detectable by Epithelial Mapping Keratoconus No Front Surface Cone Anterior stromal surface bulging Back Surface Cone
38. Results Case 1: True keratoconus Case 1 Diagnosis: KERATOCONUS OS Age 25 years Ks (D) 45.25/43.25 @ 76 Rx -1.00 -0.50 x150 BSCVA 20/16 Case 1 : NORMAL Epithelium Stroma Cornea
39. Results Case 2: False Keratoconus Case 2 : Suspect Subclinical KC OD Age 31 years Ks (D) 45.0/44.3 @ 172 Rx -5.00 -0.50 x 20 BSCVA 20/16 Higher Order Aberrations Case 2 : NORMAL Coma 3.05 µm Sph Ab 0.77 µm HO RMS 0.44 µm Epithelium Stroma Cornea
40. Case 3: Keratoconus With Normal Topography Elevation Front Pachymetry Elevation Back Elevation Front Pachymetry Elevation Back Case 3 Diagnosis: NORMAL Age 51 years Ks (D) 43.5/42.87 @ 120 (not steep) Rx -4.00 -0.50 x 35 (no cylinder) BSCVA 20/1 2.5 (no drop in BSCVA) Sagital Curvature Total Optical Power Pentacam: Progression of Corneal Thickness Orbscan Pentacam NORMAL Epithelium Stroma Cornea Keratoconus diagnosis may have been missed using surface topography screening alone Case 3 Diagnosis: KERATOCONUS
41. Are These Topographies Keratoconus? OS OD CASE 2 CASE 1 CASE 3 OD ATLAS Diagnosis Normal Keratoconus Keratoconus Final Diagnosis Including Epithelial Thickness Profile
42. Keratomileusis Early Cohort vs Modern LASIK Keratomileusis LASIK Range of myopia Up to -27.00 D 86% above -7.01 D Rarely treated above -10.00 D Screening for keratoconus None, keratoconus unknown Topography unavailable Awareness of keratoconus Astigmatism, steep & thin corneas Front & back surface topography Future advances – epithelial thickness profiles, corneal stiffness Depth of keratectomy Deep resection: 300-350 µm in all eyes Original microkeratome: inaccurate & imprecise Microkeratomes more accurate & precise Thin flaps commonly used: avg 110 µm Accurate measurement of corneal thickness and residual stromal bed Low myopia - low ablation depths Ectasia 2.8% from the original cohort ~ 0.06% (more later)
47. Artemis B-Scan: 6 Months Post LASIK Artemis B-Scan (above) of VisuMax Flap 6 months post LASIK. Edge detection by I-scan digital signal processing (red outline, below) based on raw scan data
48. Keratomileusis Early Cohort vs Modern LASIK Keratomileusis LASIK Range of myopia Up to -27.00 D 86% above -7.01 D Rarely treated above -10.00 D Screening for keratoconus None, keratoconus unknown Topography unavailable Awareness of keratoconus Astigmatism, steep & thin corneas Front & back surface topography Future advances – epithelial thickness profiles, corneal stiffness Depth of keratectomy Deep resection: 300-350 µm in all eyes Original microkeratome: inaccurate & imprecise Microkeratomes more accurate & precise Thin flaps commonly used: avg 110 µm Accurate measurement of corneal thickness and residual stromal bed Low myopia - low ablation depths Ectasia 2.8% from the original cohort ~ 0.06% (more later)
49. What else do we know about the long-term safety of LASIK? If ectasia were common, surgeons would know about it
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55. Keratomileusis Early Cohort vs Modern LASIK Keratomileusis LASIK Range of myopia Up to -27.00 D 86% above -7.01 D Rarely treated above -10.00 D Screening for keratoconus None, keratoconus unknown Topography unavailable Awareness of keratoconus Astigmatism, steep & thin corneas Front & back surface topography Future advances – epithelial thickness profiles, corneal stiffness Depth of keratectomy Deep resection: 300-350 µm in all eyes Original microkeratome: inaccurate & imprecise Microkeratomes more accurate & precise Thin flaps commonly used: avg 110 µm Accurate measurement of corneal thickness and residual stromal bed Low myopia - low ablation depths Ectasia 2.8% from the original cohort ~ 0.06% (more later)
56. What else do we know about the long-term safety of LASIK? Ectasia in the Peer-Reviewed Literature
57. Ectasia: Peer-Reviewed Literature Is 0.12%-0.66% a realistic rate of ectasia? Report No. of Ectasia/ No. Procedures Percentage Pallikaris JCRS 2001 19/2,873 0.66% Lyle JCRS 2001 1/332 0.30% Rad JRS 2004 14/6,941 0.20% Reinstein JRS 2006 6/5,212 0.12%
71. Subset of Population: Moria Flap Thickness Which means that 6.3% flaps will be at least 50 µm thicker than intended Intended Flap Thickness 160 µm Average Flap Thickness 163.6 µm Flap Thickness Bias +3.6 µm Flap Thickness Standard Deviation 30.3 µm
78. Lifetime Risk Factors Source: National Safety Council; http://www.nsc.org/research/odds.aspx Chance of ectasia about 1 in 2,000 One Year Odds Lifetime Odds All injury deaths 1,765 23 All accident deaths 2,794 37 Motor vehicle 6,078 80 Pedestrian 44,009 578 Fire & flames 70,913 932 Poisoning by venomous animals, plants 3,901,235 51,265 Dog bite 11,534,087 151,565 Lightning 4,210,857 55,333 Choking 82,746 1,087 Drowning in bathtub 803,891 10,564 Struck by falling object 362,410 4,762 Firearm missile 233,937 3,074 Fireworks 29,476,000 387,332 Children murdered by mothers 226,728 2,979 Children murdered by fathers 26,527,135 348,582
94. Complication Rate – Prof Reinstein FLAP COMPLICATIONS Eyes out of 13,148 % Lose 2 Lines Free Cap 1 (0.01%) 0.0000000% Thin Flap 2 (0.02%) 0.0000000% Incomplete Flap (no ablation) 6 (0.05%) 0.0000000% Corneal Perforation 0 (0.00%) 0.0000000% Blindness (total loss of vision) 0 (0.00%) 0.0000000% Corneal scarring reducing vision 0 (0.00%) 0.0000000% Inflammation with decrease of vision 1 (0.01%) 0.0000000% Infection 0 (0.00%) 0.0000000% Epithelial Ingrowth (requiring further surgery) 21 (0.19%) 0.0000000% Need for corneal transplantation 0 (0.00%) 0.0000000% Keratectasia 0 (0.00%) 0.0000000% LASER COMPLICATIONS Eyes out of 13,148 % Lose 2 Lines Visually sig. decentrations 0 (0.00%) 0.0000000% Laser parameter data entry error 3 (0.03%) 0.0000000%
95. What more do we know about the long-term safety of LASIK now ? More long term follow-up studies
96. Published Long-Term LASIK Outcomes - Myopia 90 eyes Mean SE: -4.85 D B&L Technolas 217 Hansatome Optical zone: 5.79 mm Stability Safety 0.0% lost 2 lines 7% lost 1 line 51% no change 42% gain 1 or more lines No ectasia 0 to -3 D -6 to -13 D -3 to -6 D All
97. Published Long-Term LASIK Outcomes - Myopia 107 eyes Mean SE: -15.71 D Summit, Technolas 116, MEL60 ACS 160 Optical zone: 6 mm Stability Safety
98. Published Long-Term LASIK Outcomes - Myopia 11 eyes Mean SE: -12.96 D MEL60 Draeger lamellar rotor keratome 150 Optical zone: 5 mm Stability Safety 0.00 -0.50 -0.96 -1.05 -1.14 -12.96
99. Published Long-Term PRK Outcomes - Hyperopia Stability Safety 40 eyes Mean SE: +4.70 D Summit Technology SVS Apex Plus Optical zone: 6 mm 5% lost 2 lines 30% lost 1 line 65% no change or improved No ectasia
100. Published Long-Term LASIK Outcomes - Hyperopia Stability Safety 47 eyes Mean SE: +3.58 D Summit Technology SVS Apex Plus Moria LSK-One 180 Optical Zone: 6 mm 0.0% lost 2 lines 2.1% lost 1 line 57.4% no change 40.5% gain 1 or more lines No ectasia
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103. LASIK is safe in the long run; looking back at 50 years of lamellar corneal surgery Dan Z Reinstein MD MA(Cantab) FRCSC FRCOphth 1,2,3,4 Timothy J Archer, MA(Oxon), DipCompSci(Cantab) 1 1. London Vision Clinic, London, UK 2. St. Thomas’ Hospital - Kings College, London, UK 3. Weill Medical College of Cornell University, New York, USA 4. Centre Hospitalier National d’Ophtalmologie, (Pr. Laroche) , Paris, France Thank You
Hinweis der Redaktion
FFKC: demonstrable topographic abnormalities consistent with keratoconus in the absence of clinical evidence of keratoconus
FFKC: demonstrable topographic abnormalities consistent with keratoconus in the absence of clinical evidence of keratoconus
The first commercial prototype Artemis, the Artemis 1, was built in 1999. The innovations here were to reverse the waterbath setup with a specially designed head rest that would keep the head motionless during scanning.It is FDA approved. This scanner is currently being used routinely at the London Vision Clinic in London where Dr. Reinstein is medical director. Setup and scan time is approximately 3-4 minutes per eye.
This is an example of a Bscan image in a patient 2 months after LASIK. The four interface’s are clearly visible; the epithelium, Bowman’s, flap and corneal back surface.
Without back surface – PRK With back surface – nothing If epithelium had been thick over the back surface apex – PRK and included in this study But, epithelium was thin – nothing
Using the model, we calculated the predicted rate of ectasia (in eyes per million) for different microkeratomes using published flap thickness statistics. The table is sorted in ascending order of rate of ectasia.
Using the model, we calculated the predicted rate of ectasia (in eyes per million) for different microkeratomes using published flap thickness statistics. The table is sorted in ascending order of rate of ectasia.
It turns out that the microkeratomes with the lowest predicted rate of ectasia all have negative bias (ie the labeled flap thickness is higher than the actual average flap thickness), and the microkeratomes with highest predicted rate of ectasia have positive bias (ie the labeled flap thickness is lower than the actual average flap thickness). Negative bias significantly reduces the probability of obtaining a keratectomy depth lower than predicted.
Similarly, microkeratomes with the lowest predicted rate of ectasia also have a low standard deviation and the microkeratomes with highest predicted rate of ectasia have a high standard deviation. A lower standard deviation reduces the probability of obtaining a keratectomy depth lower than predicted.
This is an example of the contrast sensitivity with the previous generation laser – the contrast sensitivity was seen to drop following LASIK The design and development of the MEL80 CRS-Master was focused on finding solutions to the quality of vision
All MEL80 myopia patients with preop contrast & 6 months followup & no BSCVA >20/20
