Known and Potential Complications of SMILE

Walter Sekundo

Philipps University Marburg/Germany

The author have no financial interest in any topics related to this study. Prof. Sekundo is a member of the scientific board of Carl Zeiss Meditec AG

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pre-laser cut

•  Failure to obtain an adequate suction

•  Correct treatment pack size (S in myopic cases)

•  Use speculum with suction

•  VisuMax internal settings o.k.? (Hotline)

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•  Watch the 1st Purkinje projection (obeservation mode) •  Apply suction after ≅ 85-90% applanation

•  Do not apply suction > 3 times

*Lazaridis & Sekundo, JRS 2014

pre-laser cut

Decentration (mm) from corneal apex

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42

10

1

9

35

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2

0

5

10

15

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25

30

35

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45

0-0,2 0,2-05 0,5-1 >1

•  ReLEx •  Fs-Lasik

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32

12

1

9

28 31

1 0

5

10

15

20

25

30

35

0-0,2 0,2-05 0,5-1 >1

Decentration (mm) from pupil centre

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Pre-operative

•  Centration: minor nasalisation is normal (angle κ)

*Lazaridis & Sekundo, JRS 2014

ReLEx Mean Decentration: 0.326mm Nasalisation of the fixation in relation to the pupil centre = positive angle κ

fs-LASIK Mean Decentration: 0.452mm Centration is randomly distributed

-1,50

-1,00

-0,50

0,00

0,50

1,00

1,50

-1,50 -1,00 -0,50 0,00 0,50 1,00 1,50

OD, OS

-1,50

-1,00

-0,50

0,00

0,50

1,00

1,50

-1,50 -1,00 -0,50 0,00 0,50 1,00 1,50

OD, OS

•  Control of cyclorotation is a problem unless adjusted manualy by Contact Glass rotation

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•  Suction loss

•  intermittend laser stop (fluid in interface)

•  Poor dissection

•  Incomplete cut (e.g. incomplete sidecut)

During laser cut

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Suction loss: 3.2%*

1.Convert to ReLEx FLEx or continue with SMILE with a larger cap, if the bottom plane has been accomplished

2. Abort procedure, if „suction loss“ occurred during the first cut: perform microkeratome Lasik or PRK with MMC or phakic IOL later

3. A vertical opening cut is possible at any time

4. Software „flap making tool“ can be used later in time

1) Lamellar ring 2) Overlap 3) Side Cut with Hinge

Hinge width

Coutesy of R.Shah

VisuMax® software assists you in decision making:

* Wong CW et al , JCRS 2014

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•  Epithelial slugh off (basement membrane dystrophy): Contact lens, steroids (DLK!)

•  Cap perforation & tear: I usually use >120µm cap, adapt and leave: usually heals well

•  Tear at the incision site for SMILE: usually not a big problem

•  Incomplete side cut: always keep a micro-blade in the OR

•  „Wrong plane“: -  use „hook movement“ from anterior lip

or invert the edge (incisions >3.5mm) -  separate from distal end with Mehta reversed

dissector*

Dissection

tear

*Liu Y-C, Pujara T, Mehta JS, PLOS One 2014 8

Microstriae after SMILE?

•  ReLEx SMILE does not induce any microstriae in the cap when examined by slit-lamp, unless stained with fluorescein (D. Reinstein)

•  Manual stretching + ironing toward the periphery at the conclusion of procedure helps

I

BLMD Grade 2

BLMD Grade 0

* Messerschmidt-Roth & Sekundo 2013

Bowman‘s Layer Microdistorsions (BLMD)

•  can be detected by OCT after SMILE •  correlate with the extent of correction* •  BLMD do not produce visual symptoms in the mid-term

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Post-op 1.  Epithelial plug

2.  Lenticule "left-overs" and debris in the interface

3.  DLK

4.  „Haze" in the interface

5.  Ectasia

6.  Infection 7.  Unusual cases

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•  Always only a plug (so far) •  Observe •  Intervene only if progressive •  Put a stich

Epithelial ingrowth

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•  Very serious complication, if –  Within optical zone (more

prone in hyperopic treatments) –  Usually at the edge in myopic

treatment •  Irregular astigmatism •  „Central island“ in hyperopia

treatment (experimental) –  Dissect from the middle

toward the periphery, respect counter-action

–  Use curved dissector –  Use forceps only after

complete dissection

Lenticule remains

Courtesy J. Gertnere

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•  Usually at the edge •  Do not affect vision •  Consider a longer course of

steroids to prevent local inflammation

Debris

Courtesy J. Gertnere

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•  DLK –  Incidence 1.6%*

•  erosion at the opening incision •  thin lenticules ≈ 100µm

–  Use steroids vigorously

•  Haze –  After DLK –  As „primary scarring“ –  Usually does not affect vision –  Consider a longer course of

steroids (e.g. FML) after difficult dissection

Haze/DLK

Courtesy J. Gertnere

*Zhao J et al, JCRS 2015

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•  Decentration (has been discussed above): never saw clinical significance. Otherwise topography guided excimer ablation (Ivarsen et al.)

Decentration

Courtesy J. Gertnere

My worst case

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Ectasia

Courtesy J. Gertnere

True ectasia: only one case reported after FLEx (Blum M. et al). Misdiagnosed form fruste Keratoconus: CXL done

Ectasia secondary to forceful dissection („via falsa“): RGP, DALK, if CL intolerance

•  Infection: no reports in the literature, but

probably not very different from fs-Lasik •  *Simultaneous uneventful SMILE for -6D

•  Post-op UDVA

•  OD=0.8

•  OS=1.4

•  Deterioration of vision OD

•  Unchanged OS

* Courtesy of K. Shimizu, Kitasato University/Japan

Infection/unusual cases

DDx: 1) Pressure induced interlamellar keratitis 2) low grade infection

CDVA=0.4 (-3.75 cyl -3.00 Ax10) IOP = 9.7 mmHg, IOPcc = 27 mmHg

Edema and interface fluid collection

Shimizu, Kitasato University/Japan

Courtesy Prof Shimizu

3/12 post-op

CDVA=0.5 (-3.75 cyl -3.00 Ax 10) IOP = 9.0 mmHg, IOPcc = 20.9 mmHg

Residual edema and interface fluid collection

2/52 after re-intervention

Shimizu, Kitasato University/Japan

Courtesy Prof Shimizu

2/52 after 1) Pocket irrigation 2) Steroids discontinued 2) IOP lowering medication

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Conclusion

•  Despite its novelty, complications after SMILE are rare, even with new users

•  In the vast majority they are similar to fs-Lasik and can be addressed accordingly

•  However, SMILE requires more manual work and has a steep learning curve

•  Surgeons novel to this technique should stick to the suggested training protocol