32nd International Congress of the Hellenic Society of Intraocular Implant and Refractive Surgery

Transcription

1 32nd International Congress of the Hellenic Society of Intraocular Implant and Refractive Surgery Basic Course on Refractive Surgery Ioannis Aslanides, MD, PhD, FRCOphth

2 Trans-PRK concept For this refraction: OD: x 45 OS: x 80 Would you do LASIK? If it was your son?

3 Trans-PRK concept During my collaboration with Dr Reinstein in Weill-Cornell Medical College (New York), under the supervision of Prof. Coleman, we conducted 5 years of research on the corneal epithelium using the Artemis Our joint research is a major part of my PhD thesis ( ) Ronald Silverman (I am taking the photograph) Dan Reinstein 1.High-frequency ultrasound corneal pachymetry in the assessment of corneal scars for therapeutic planning, Dan Z. Reinstein, Ioannis M. Aslanides, Ronald H. Silverman, Penny A. Asbell, D. Jackson Coleman, Contact Lens Association of Ophthalmologists, 1994 July 2.High-frequency Ultrasound Spectral Parameter Imaging of Anterior Corneal Scars Dan Z. Reinstein, Ioannis M. Aslanides, Ronald H. Silverman, Douglas Lazzaro, Mark Rondeau, Hanna Rodriquez, Contact Lens Association of Ophthalmologists, 1995 October 3.High frequency ultrasound imaging in papillary block glaucoma, Ioannis M. Aslanides, Peter E. Libre, Ronald H. Silverman, Dan Z. Rein stein, Douglas R. Lazzaro, Mark J. Rondeau, Gregory K. Harmon, D. Jackson Coleman, British Journal of Ophthalmology, 1995 November 4.Iridoschisis: high frequency ultrasound imaging. Evidence for a genetic defect? Danias J, Aslanides IM, Eichenbaum JW, Silverman RH, Reinstein DZ, Coleman DJ., British Journal of Ophthalmology, 1996 December 5.High frequency ultrasound evaluation of radial keratotomy incisions, Lazzaro DR, Aslanides IM, Belmont SC, Silverman RH, Reinstein D Z, Muller JW, Lloyd HO, Coleman DJ., Journal of Cataract and Refractive Surgery, 1995 July

4 What is ASLA/cTEN All-Surface Laser Ablation (ASLA) Customized TransEpithelial No-touch (cten) are a: no-touch single-step Transepithelial PRK technique that allows: simultaneous ablation of the epithelium and the stroma shorter overall treatment time minimal the risk of corneal dehydration

5 ASLA (TransPRK) Schwind Amaris 750S 750Hz 0.54 mm spot size Super-Gaussian beam profile cten ivis ires 1000Hz 0.65 mm spot size Gaussian beam profile

6 What is ASLA/cTEN ASLA s approach to correct aberrations and refractive errors: 1. sequential stromal treatment 2. removal of epithelium of the treated area using a defined epithelial thickness profile

7 Composition of the ASLA beam profile The stromal component of the beam

8 Composition of the ASLA beam profile The epithelial component of the beam

9 Composition of the ASLA beam profile The resulting ASLA beam profile

10 Composition of the ASLA beam profile Better simulation the corneal with the Smart Pulse Technology Using a three-dimension geometric model based on a fullerene structure corneal representation in two (left) and three (right) dimensions three-dimensional fullerene model The corneal curvature can be represented in a more realistic way laser beam can safely ablate areas that are very close to each other *Trans advanced surface laser ablation (TransPRK) outcomes using SmartPulseTechnology, Aslanides IM, Kymionis GD, Cont Lens Ant erior Eye Feb;40(1):42-46

11 Difference with conventional Trans-PRK a custom epithelial profile has been generated to remove the epithelium, targeting 55 μm centrally, and 65 μm peripherally (with Schwind s latest software the epithelial profile can be customized too) the ablation is not carried out as two distinct steps, but rather as a single continuous profile, mitigating the risk of dehydration the profile uniquely applies the stromal component of the ablation first, over the epithelium, prior to the additive epithelial profile

12 Difference with conventional Trans-PRK PTK+PRK ASLA

13 Our experience with ASLA (since 2010)

14 Corneal Biodynamics The cornea behaves as a micro dome, subject to a uniform pressure from inside to outside.

15 Corneal Biodynamics The cornea behaves as a micro dome, subject to a uniform pressure from inside to outside.

16 Corneal Biodynamics The parameters necessary to study the corneal dynamics and to evaluate the entity of its deformations are: Corneal diameter Corneal mean curvature Corneal thickness (pachymetry) Intra-ocular pressure Scleral indentation Corneal Elasto-plastic modulus Corneal Viscosity

17 Corneal Biodynamics Corneal Diameter is the most relevant parameter which affects the deformation The corneal deformation can be approximately related to the 4 th power of the total length L1 L2

18 Corneal Biodynamics The deformation induced by the thickness is proportional to the 3 rd power of the thickness. S1 S2

19 Corneal Biodynamics The average curvature of the cornea is also an important parameter to evaluate the corneal dynamic R1 R2

20 Corneal Biodynamics The intra-ocular pressure provides a linear contribution to corneal deformation

21 Corneal Biodynamics Scleral indentation cannot be taken in adequate account in the analysis due to a lack of objective data. Nevertheless, any possible scleral indentation defect can be considered as a dome based on weak foundation

22 Corneal Biodynamics The Elastic modulus has a linear contribution to corneal deformation The elastic deformation recedes when the applied force are ter minated, while the plastic defor mation has a permanent nature. However, the cornea, due to its geometry, generally operates in the elastic range. σ Elastic phase plastic phase ε

23 Corneal Biodynamics The viscosity of the corneal structure may induce a progressive deformation over the time It has a progressive nature and manifests over time under the presence of a permanent stress action, as the intraocular press ure A typical case of a progressive visco-elastic deformation is represented by the keratoconus pathology

24 Corneal Biodynamics At early stages, a local area of weakness of the elastic modulus, may be identified (due to local deficiencies in the crosslinking of the stromal collagen fibers???)

25 Corneal Biodynamics Later stages Stress induced by the IOP Corneal thickness decrease Viscous slipping of the stromal fibers Further local increase of deformation Local reduction of the corneal thickness Further increase of the local stress is induced

26 Why ASLA/cTEN fewer complication risks steeper learning curve long-term results comparable to or even better than LASIK and is: cost efficient quick Practically for EVERY refractive surgeon

27 Why ASLA/cTEN All patients have LASIK procedure in their mind Chair-time Marketing tools

28 Why ASLA/cTEN Suitable for: myopia astigmatism thin corneas suboptimal topography hyperopia???

29 Problems we face Haze Epithelial healing Visual rehabilitation Pain

30 Problems we face

31 Going forward/solutions Beam profiles causing less thermal effect and tissue damage (post-operative stromal surface than before) Pharmaceutical reduction of the pain (CLs soaked with eye drops, tabs e tc.) Healing moderators (RGTAs e.g. Cacicol) Mitomycin-C Combination with CXL TES (Temporary Epithelial Substitute)? Utilize artificial intelligence/computational methods (simulated biomechanical models)

32 Evidence based medicine Results regarding the safety, efficacy and stability of ASLA have been published by lots of groups around the world The results of ASLA for myopic patients are equal to those for LASIK1,own data after one month. The long-term results may even be superior to LASIK. 2,3 There are fewer dry eyes in comparison to LASIK treatments. 4 There are no flap complications, because there is no corneal flap. Through the use of MMC the cornea remains clear. Serious haze is a rarity. 5 1Arbelaez MC, Aslanides IM, Barraquer C, Carones F, Fueremannova A, Neuhann T, Rozsival P. LASIK for Myopia and Astigmatism Using the SCHWIND AMARIS Laser: An International Multicenter Trial. Refract Surg 2010;26: Miyai T, Miyata K, Nejima R, Honbo M, Minami K, Amano S. Comparison of laser in situ keratomileusis and photorefractive keratectomy r esults: Long-term follow-up. Cataract Refract Surg 2008; 34: Luger MHA, Ewering T, Arba-Mosquera S. Consecutive myopia correction with trans epithelial versus alcohol-assisted photorefractive kera tectomy in contralateral eyes: One year results. Cataract Refract Surg 2012; 38: Reynolds A, Moore J, Naroo S, Moore C, Shah S. Excimer laser surface ablation a review. Clinical and Experimental Ophthalmology 2010; 38: Leccisotti A. Mitomycin-C in hyperopic photorefractive keratectomy. Cataract Refract Surg 2009; 35:

33 Evidence based medicine The corneal surface needs an average of 2.5 days to heal. 6 After the surface heals, good vision is rapidly restored for myopic patients 7 (8-9/10 in Snellen lines, 1 week after the treatment) Using modern bandage contact lenses and topical anesthetics, the discomfort time has been reduced. 8 Because we use just one laser in a one-step, no-touch procedure, with very few instruments, the treatment is very cost-efficient. 6 Fadlallah A, Fahed D, Khalil K, Dunia I, Menassa J, El Rami H, Transepithelial photorefractive keratectomy: Clinical results. Catarac t Refract Surg 2011; 37: Aslanides IM, Kymionis GD., Trans advanced surface laser ablation (TransPRK) outcomes using SmartPulseTechnology, Cont Lens Anterior Eye Feb;40(1): Aslanides IM, Selimis VD, Bessis NV, Georgoudis PN, A pharmacological modification of pain and epithelial healing in contempo rary transepithelial all-surface laser ablation (ASLA), Clin Ophthalmol Apr 15;9:685-90

34 Evidence based medicine We have published our own experience and results with ASLA Cataract & Refractive Surgery Today, Europe, June 2011

35 Evidence based medicine We have published our own experience and results with ASLA Clin Ophthalmol 2012;6: Epub 2012 June 27 J Optom Jan-Mar;8(1):27-32 Epub 2014 Jun 13

36 Evidence based medicine We have published our own experience and results with ASLA Open Ophthalmol J Oct 18;7:63-8 ecollection 2013 Clin Ophthalmol Dec 30;9:33-41 ecollection 2015

37 Evidence based medicine We have published our own experience and results with ASLA Clin Ophthalmol Apr 15;9: ecollection 2015 Cont Lens Anterior Eye Feb;40(1): Epub 2016 Nov 22

38 Refractive market Global demand for refractive surgery Annual growth of 5.5% annual procedure volume (in millions) Source: Market Scope, 2016 Refractive Surgery Report: A Global Market Analysis for 2015 to 2021

39 Refractive market Excimer laser revenues at the manufacturer level (including equipment sales, procedure fees, and maintenance) will show slight growth at a compounded rate of 1.9% over the next five years Femtosecond laser revenues will grow at a hefty compounded growth rate of 15.5% as the devices continue to increase in popularity and surgeons expand their use of Zeiss small incision lenticule extraction (SMILE). It has secured crucial approvals in the US and Europe and gaining popularity in India and China. Femtosecond flap-making devices are used in approximately 55% of total LASIK procedures worldwide, and we expect this share to grow during the next five years, especially in markets outside the US. Source: Market Scope, 2016 Refractive Surgery Report: A Global Market Analysis for 2015 to 2021

40 Refractive market Average payment for laser refractive surgery will decline at a compounded rate of 0.2% due to increasing competition among laser centers and doctors, plus growth in demand in Asia and other emerging markets where laser refractive surgery is lower in price. Some of this decline will be offset by an increase in premium procedure share due to a higher share of femtosecond laser procedures, new advanced ablation patterns, and newer technology adoption. The number of refractive surgeons and laser centers to grow in step with changes in demand. Most of the growth is expected in China, India, and other emerging market areas. Overall, we look for the number of laser centers worldw ide to grow at a compounded rate of 3.2 percent and the number of refractive surgeons to grow at 1.4 percent over the next five years. Source: Market Scope, 2016 Refractive Surgery Report: A Global Market Analysis for 2015 to 2021

41 What do my patients demand Safety Predictability Fast visual recovery Cost-effectiveness No pain

42 Who is the most important in your theatre? The patient? THE ENGINEER The surgeon? The nurse?

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44 Thank you for your attention!!! Parodos Anopoleos, Plateia Eleftherias Heraklion, Crete,