Top Laser Surgery Expert Dr. David Robinson

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A Comparison of LASIK Vs SMILE

• Dr. David Robinson M.B. B.S. B.Sc. (MED)
  F.R.A.N.Z.C.O. F.R.A.C.S

david_at_sydneyvision.com.au www.sydneyvision.com.au
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Techniques Being Compared

• SMILE Small-incision Lenticule Extraction
• LASIK Wavefront Guided Femtosecond
  Laser-assisted Laser in Situ Keratomileusis

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Literature Reviews

• LASIK articles published between 2008 and 2015
  containing clinical outcomes were reviewed and
  graded. (Sandoval et al.)
• All studies of SMILE, and wavefront guided
  femtosecond laser-assisted LASIK published from
  January 2012 to September 2015 were reviewed.
  (Pinero et al.)

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LASIK Articles Reviewed (Sandoval et al.)

• LASIK articles published between 2008 and 2015
  containing clinical outcomes were reviewed and
  graded.
• There were 97 relevant articles (67,893 eyes)
• Conventional (standard) treatment, and Advanced
  treatment (wavefront-guided, wavefront-optimized,
  or topography-guided) were catagorized

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LASIK History

• LASIK is one of the most commonly performed
  elective procedures
• More than 16 million LASIK procedures performed
  globally
• LASIK was introduced by Pallikaris et al. in
  1990.
• Excimer laser approved by FDA in 1995
• LASIK approved by FDA in 1999

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LASIK Visual Outcomes
Loss or gain of CDVA

• In aggregate, more than twice as many eyes gained
  2 or more lines of CDVA (1.45) as lost 2 or more
  lines of CDVA (0.61)
• The percentage of eyes with a loss of 2 or more
  lines was statistically significantly lower in
  advanced group (0.6), than in the conventional
  group (0.94)
• The percentage of eyes with a loss of 2 or more
  lines was statistically significantly higher in
  eyes treated for hyperopia (2.13), than myopia
  (0.95)

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LASIK Visual Outcomes
UDVA Results

• 90.8 of eyes had UDVA 20/20 or better p/op
• 99.5 of eyes had UDVA 20/40 or better p/op
• Postoperative UDVA statistically significantly
  better in advanced treatment results (-0.04
  logMAR), than conventional treatment results
  (0.05 logMAR) the difference being almost 1
  line

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LASIK Visual Outcomes
UDVA Results (cont)

• No difference in results between
  wavefront-guided, wavefront-optimized, or
  topography-guided treatments in the advanced
  treatment group

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LASIK Visual Outcomes
UDVA Results (cont)
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LASIK Visual Outcomes
UDVA Results (cont)
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LASIK Visual Outcomes
Residual SE Refrative Error

• 90.9 within 0.50D
• 98.6 within 1.0D
• In 95 eyes, the mean SE was within 0.25D

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LASIK Outcomes
Corneal Sensation Dry Eye

• Multiple studies have shown that corneal
  sensation returns to normal in almost all cases
  at 6 months p/op
• 0.8 incidence of dry eye 1 year p/op (Bower et
  al.)
• Preoperative dry eye predictive of postoperative
  dry eye

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LASIK Outcomes
Patient Satisfaction

• 98.7 of all patients were satisfied or very
  satisfied after LASIK surgery
• 97 of patients (in response to a survey) said
  they felt they were better off having had the
  surgery (Kezirian et al.)

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LASIK Outcomes
Advanced LASIK vs Standard LASIK

• Mean UDVA for conventional LASIK was within a
  half a line of 20/20
• UDVA in advanced treatment group was nearly 1
  line better than in the conventional group

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LASIK Outcomes
Advanced LASIK vs Standard LASIK (cont)

• The aggregate data from a large number of recent
  articles demonstrates the outcomes of modern
  LASIK are significantly better than when the
  technology was first introduced.
• Some reasons for this are likely to be
• Improved diagnostic and laser technology and
  patient selection,
• better refinement of nomograms,
• more sophisticated ablation patterns
• Introduction of new technology (femtosecond laser
  for flap creation etc)

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SMILE and LASIK Articles Reviewed (Pinero et al.)

• All studies of SMILE and wavefront-guided
  femtosecond laser-assited LASIK published from
  January 2012 to September 2015 were reviewed

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Visual Outcomes (cont)
Comparison of studies

• SMILE 66.7 of studies reported 80 or more
  eyes achieving 20/20 or better UDVA
• LASIK all studies reported 80 or more eyes
  achieving 20/20 or better UDVA
• (Figure 2)

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Visual Outcomes (cont)
Comparison of studies

• SMILE 40 of studies reported 90 or more eyes
  achieving 20/20 or better UDVA
• LASIK 75 of studies reported 90 or more eyes
  achieving 20/20 or better UDVA
• (Figure 2)

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Visual Outcomes (cont)
Figure 2
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Visual Outcomes (cont)
CDVA

• No clear difference in loss of lines of CDVA
• Higher percentage of eyes gained lines of CDVA
  with LASIK than SMILE (possibly due to less
  corneal backscatter present early post LASIK)

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Refractive Outcomes
Spherical Equivalent

• SMILE Mean P/OP SE of -0.01D to -0.33D
• LASIK Mean P/OP SE of -0.02D to -0.17D
• (figure 5)

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Refractive Outcomes
Spherical Equivalent (Cont)

• SMILE 67.6 - 100 within 0.50D of target SE
• LASIK 80 - 100 within 0.50D of target SE
• SMILE 95 - 100 within 1.0D of target SE
• LASIK 96 - 100 within 1.0D of target SE
• (figure 5)

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Refractive Outcomes (SE)
Figure 5
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Refractive Outcomes
Spherical Equivalent (Cont)

• Suggests a slight trend toward myopic residual SE
  in SMILE which would explain the lower UDVA

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Refractive Outcomes
Mean P/OP Astigmatism at 12 months

• SMILE -0.40D 0.32D (Gyldenkerne et al.)
• SMILE -0.36D 0.38D (Qian et al.)
• LASIK -0.28D 0.30D (He et al.)
• LASIK -0.09D 0.13D (Prakash et al.)

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Refractive Outcomes
Further P/OP Astigmatism results

• SMILE 95 eyes 0.5D cyl or less (Reinstein et
  al.)
• SMILE 92 eyes 0.5D cyl or less (Sekundo et
  al.)
• SMILE 79.1 eyes 0.5D cyl or less (Yao et al.)
• LASIK 87 eyes 0.5D cyl or less (He et al.)
• LASIK 95 eyes 0.5D cyl or less (Yu and Manche)
• LASIK 94 eyes 0.25D cyl or less (Prakash et
  al.)

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Ocular Corneal Aberrometric Outcomes
Mean Coma RMS

• SMILE 0.24um to 0.706um
• LASIK 0.15um to 0.28um
• Higher levels of coma seem to be related to mild
  levels of treatment decentration

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Corneal Sensation and Dry Eye Outcomes

• Corneal sensitivity Significantly less decrease
  in corneal sensitivity in SMILE than LASIK in
  early postoperative measures (1 week, 1 month, 3
  months)
• No significant difference in corneal sensitivity
  at 6 months post op.
• TBUT Less decrease in SMILE in the early
  postoperative period
• Schirmers Test Less decrease in SMILE in the
  early postoperative period

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Re-treatment Comparisons

• Limited evidence of the outcomes of SMILE
  re-treatments
• Results of surface ablation re-treatments in
  SMILE eyes are poor
• Successful re-treatments have been reported post
  LASIK

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Other Comparisons of note

• Increase in backscattered light intensity early
  postoperatively after SMILE compared with LASIK
  which may be the cause of the limitations in
  early postoperative SMILE outcomes
• Biomechanical changes occur after both procedures
  with no evidence supporting the superiority of
  one technique over the other
• Scientific evidence supporting the stability of
  results exists for LASIK, but does not yet exist
  for SMILE

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References

• Sandoval H.P, Donnenfeld E.D, Kohnen T, Lindstrom
  R.L, Potvin R, Tremblay D.M, Solomon K.D. Modern
  Laser in situ keratomileusis outcomes. J Cataract
  Refract Surg 2016 421224-1234
• Pinero D.P, Teus M.A. Clinical outcomes of
  small-incision lenticule extraction and
  femtosecond laser-assisted wavefront-guided laser
  in situ keratomileusis. J Cataract Refract Surg
  2016 421078-1093

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Thank You!

• Dr. David Robinson
• M.B., B.S., B.Sc. (MED), F.R.A.N.Z.C.O.,
  F.R.A.C.S.

david_at_sydneyvision.com.au www.sydneyvision.com.au