Clinical Oph halmology
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h p://dx.doi.o g/10.2147/OPTH.S99394
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ORIGINAL RESEARCH
open access o scien i ic and medical esea ch
Open Access Full Tex A icle
Fem osecond lase s o lase in si u ke a omileusis:
a sys ema ic e iew and me a-analysis
Anne Huh ala1
Juhani Pie ilä1,2
Pe i Mäkinen1,2
Hannu Uusi alo1–3
1Silmäasema Eye Hospi al, 2SILK,
Depa men o Oph halmology,
School o Medicine, Uni e si y o
Tampe e, 3TAUH Eye Cen e , Tampe e
Uni e si y Hospi al, Tampe e, Finland
Pu pose: The aim o his s udy was o e iew and me a-analyze whe he he e a e di e ences
be ween epo ed em osecond (FS) lase s o lase -assis ed in si u ke a omileusis (LASIK)
in e ms o e icacy, p edic abili y, and sa e y as p ima y ou comes and co neal lap hickness
measu emen s and p e- and pos ope a i e complica ions as seconda y ou comes.
Me hods: A comp ehensi e li e a u e sea ch o PubMed, Science Di ec , Scopus, and Coch ane
CENTRAL T ials Lib a y da abases was conduc ed o iden i y he ele an p ospec i e andom-
ized con olled ials o FS lase s o LASIK. Thi y-one a icles desc ibing a o al o 5,404 eyes
we e included.
Resul s: Based on e icacy, In aLase FS 10 and 30 kHz ga e he bes esul s. Based on p e-
dic abili y and sa e y, he e we e no di e ences be ween a ious FS lase s. FEMTO LDV and
In aLase FS 60 kHz p oduced he mos accu a e lap hicknesses. In aLase and Wa eligh
SF200 had he ewes in aope a i e complica ions. In aLase, Visumax, and Wa eligh FS200
had he mos seldom pos ope a i e complica ions.
Conclusion: The e we e dissimila i ies be ween di e en FS lase s based on e icacy and
in aope a i e and pos ope a i e complica ions. All FS lase s we e p edic able and sa e o
making co neal laps in LASIK.
Keywo ds: em osecond lase , lase in si u ke a omileusis, LASIK, me a-analysis
In oduc ion
Lase -assis ed in si u ke a omileusis (LASIK) is he mos commonly used e ac i e
su ge y echnique o he co ec ion o myopia, hype opia, and as igma ism.1,2 The
i s phase o LASIK, he c ea ion o a co neal lap, is he mos c i ical s ep o LASIK,
and i a ec s he isual ou come o he whole p ocedu e. The lap c ea ion is ollowed
by excime lase abla ion o he exposed s oma a e which he lap is eposi ioned.
The echnological e olu ion o lap c ea ion has eme ged om mechanical manually
guided mic oke a omes o au oma ed mic oke a omes and single-use mic oke a omes,
and mos ecen ly o em osecond (FS) lase echnology.3,4 In he FS lase echnology,
FS lase pho odis up s issue a a p ese dep h and p oduces mic oca i a ion bubbles
consis ing o wa e and ca bon dioxide.5 The expansion o hese bubbles sepa a es he
co neal lamellae and o ms a esec ion plane.5
The e a e se e al FS lase s on he ma ke . In aLase, now p oduced by Abbo Medical
Op ics Inc. (San a Ana, CA, USA), was he i s FS lase ke a ome in oduced in he USA
in 2001.6 Technolas Fem osecond Wo ks a ion, o me ly known as Fem ec, by Technolas
Pe ec Vision (Munich, Ge many), was in oduced immedia ely a e he ma ke launch
o In aLase.7 FEMTO LDV by Zieme Oph halmic Sys ems (Po , Swi ze land) was
in oduced in he la e 2005, and Visumax by Ca l Zeiss Medi ec AG (Jena, Ge many)
in he all 2006.7 Wa eligh FS200 by Alcon Labo a o ies, Inc. (Fo Wo h, TX, USA)
Co espondence: Anne Huh ala
Silmäasema Eye Hospi al Tampe e,
Hämeenka u 6, FIN-33100 Tampe e,
Finland
Tel +358 50 304 0458
Email [email p o ec ed]
Jou nal name: Clinical Oph halmology
A icle Designa ion: ORIGINAL RESEARCH
Yea : 2016
Volume: 10
Running head e so: Huh ala e al
Running head ec o: Fem osecond lase s o LASIK
DOI: h p://dx.doi.o g/10.2147/OPTH.S99394
Numbe o imes his a icle has been iewed
This a icle was published in he ollowing Do e P ess jou nal:
Clinical Oph halmology
7 Ma ch 2016
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Huh ala e al
ecei ed he US Food and D ug Adminis a ion clea ance o
ma ke ing in he USA in he la e 2010.8
FS lase echnology has been inc easingly used in
LASIK. Acco ding o a poll conduc ed in 2006, .30% o he
LASIK laps we e c ea ed by FS lase ,9 while acco ding o a
Ma ke Scope’s second-qua e su ey o he yea 2010, ∼70%
o he LASIK laps we e c ea ed using an FS lase .10 As he
published me a-analysis s udies o FS lase s o LASIK ha e
been concen a ed only on In aLase,10,11 he cu en s udy
was unde aken o e iew and me a-analyze whe he he e a e
di e ences be ween epo ed FS lase s o LASIK in e ms o
e icacy, p edic abili y, and sa e y as p ima y ou comes and
co neal lap hickness measu emen s (di e ence om he
a ge lap hickness and combined s anda d de ia ion [SD])
and complica ions as seconda y ou comes.
Ma e ials and me hods
Li e a u e sea ch s a egy
Comp ehensi e li e a u e sea ches o PubMed and Science
Di ec da abases we e i s conduc ed on Decembe 2, 2013.
The li e a u e sea ch o Scopus da abase was conduc ed
on Ma ch 10, 2014, and ano he li e a u e sea ch o he
Coch ane CENTRAL T ials da abase on Oc obe 4, 2014.
A e he e iew p ocess, all he da abases we e echecked
on Decembe 28, 2015, o newe publica ions. The li e a-
u e sea ches we e conduc ed by using he ollowing e ms:
“ em osecond lase lasik clinical con olled andomized”
and “ em osecond lase lasik lap hickness con olled an-
domized” wi hou da e limi a ions. Language was es ic ed
o English. Ci a ions ini ially selec ed we e i s e ie ed
as i les by one e iewe (AH). A e he ini ial sc eening,
po en ially ele an a icles we e e ie ed as abs ac s and
sc eened by all au ho s. A e his s ep, ele an a icles we e
e ie ed as comple e pape s and assessed o compliance.
Quali y sco ing
The quali y o each s udy was assessed using he Jadad
e al12 sco e wi h a scale o 0–5. Each s udy was assessed by
h ee main aspec s o s udy design: andomizing, masking,
and pa icipan wi hd awals/d opou s. One poin was gi en
o he p esence o andomizing, masking, and pa icipan
wi hd awals/d opou s. I andomizing and blinding we e
app op ia e, one addi ional poin was added o each. S udies
sco ing ,3 poin s we e conside ed o be o low quali y.
Ou come measu es
The p ima y ou come measu es we e e icacy, p edic abili y,
and sa e y. The e icacy measu e was he p opo ion o eyes
achie ing an unco ec ed dis ance isual acui y (UDVA), an
UDVA o 20/20 o be e . The p edic abili y measu e was
e ac ion wi hin ±0.5 diop e s (D) o mean a ge sphe ical
equi alen e ac ion. The sa e y measu e was a loss o $2
Snellen lines o CDVA, a co ec ed dis ance isual acui y.
Seconda y ou come measu es we e lap hickness measu e-
men s (mean lap hickness and lap p edic abili y as SD),
and in aope a i e and pos ope a i e complica ion a es. Fo
p ima y ou come measu es, hype opic eyes we e excluded
om he analysis.
S a is ical me hods
The da a we e pooled oge he o di e en FS lase s. Pe cen -
age alues we e calcula ed back o basic coun alues in o de o
make nonpa ame ic analysis possible. S a is ical signi icance
o e icacy, p edic abili y, sa e y, and in a- and pos ope a i e
complica ions was e alua ed wi h he chi-squa e es . Co neal
lap hickness measu emen s we e also pooled oge he and
analyzed wi h he one-way analysis o a iance (ANOVA)
(SigmaPlo ; Sys a So wa e Inc., San Jose, CA, USA). In his
me a-analysis, which included se e al p e iously published
s udies, P- alue ,0.001 was conside ed signi ican .
Resul s
Resul s o he li e a u e sea ch
Figu e 1 shows he lowcha o he s udies om he ini ial
li e a u e sea ch o he inal inclusion. Based on he ull pape
e iew, 21 con olled andomized ials and en p ospec i e
o e ospec i e non andomized s udies we e included in
he me a-analysis.
P ima y ou come measu es
Table 1 shows he main p eope a i e cha ac e is ics o he
31 s udies desc ibing a o al o 5,404 eyes included in he
me a-analysis. S udies w i en in bold (nine s udies) ha e
been included in he p e iously published me a-analysis
s udies10,11 conce ning FS lase o LASIK. Pos ope a i e
cha ac e is ics o p ima y and seconda y ou comes a e
p esen ed in Table 2.
E icacy
Among he di e en In aLase ypes, he e icacy
anged om 85.1% (In aLase FS 60 kHz, se en s udies
included13–19) o 100% (In aLase FS 1020 and 30 kHz,21
Figu e 2). Fo he mos commonly epo ed In aLase FS
60 kHz, he a e age e icacy was 85.1%. In one s udy,
In aLase FS 60 o 150 kHz22 was used and i s e icacy
was 98.3%. Fo In aLase 150 kHz,19,23–25 he a e age
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Fem osecond lase s o LASIK
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Figu e 1 Flowcha o s udy selec ion.
e icacy was 93.7%. Fo FEMTO LDV,26,27 he a e age
e icacy was 91.3%. Fo Visumax18,24,28 and Wa eligh
FS200,29,30 he a e age e icacy a es we e 79.1% and
83.6%, espec i ely.
P edic abili y
The a e age p edic abili y o he di e en In aLase ypes
anged om 91.0% (In aLase FS 60 kHz14–19) o 95.9%
(In aLase FS 30 kHz;21,31 Figu e 3). FEMTO LDV26,27 had
he a e age p edic abili y o 89.4%. Fo Visumax18,24 and
Wa eligh FS200,29,30 he a e age p edic abili ies we e 87.1%
and 90.5%, espec i ely.
Sa e y
The a e age sa e y pe cen age was ze o o e y close
o ze o o all he s udied FS lase ypes (Figu e 4). Fo
In aLase FS 1532–36 and 30 kHz,21,31,37 he a e age sa e y was
0.4% and 0.7%, espec i ely. Fo In aLase FS 60 kHz,13–18 i
was 0.2%. Fo Wa eligh FS 200,29,30 i was 0.5%.
Seconda y ou come measu es
Flap hickness measu emen s
The a e age di e ence om he a ge lap hickness
o In aLase FS 3031,37 and 60 kHz13,14,16,38–40 was +0.8
and +0.6 µm, espec i ely (Figu e 5). Fo In aLase FS
15 kHz,33,34,41 he a e age di e ence om he a ge lap
hickness was much bigge , +6.7 µm. Fo FEMTO LDV,26,40,42
he a e age di e ence om he a ge lap hickness was
5.3 µm less han in ended. Fo Visumax,28,40 he di e ence
om he a ge was 10.6 µm mo e han in ended. Wa eligh
FS20029,30 p oduced co neal laps ha we e close o he
in ended alue (di e ence om he a ge lap hickness
was +0.03 µm). The a e age SD o In aLase FS 15 and
30 kHz was 15.5 and 13.8 µm, espec i ely. Fo he mos
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Huh ala e al
Table 1 Cha ac e is ics o he s udies included in he me a-analysis o em osecond lase s o LASIK
Re e ences
(au ho , yea )
Su gical p ocedu e Coun y Eyes (n) P eop mean SE (D) ± SD Follow-up
(mo)
Design Jadad e al12
quali y sco e
T an e al, 200520 In aLase FS 10 kHz USA 9 −2.58 3 Randomized 2
Du ie and S ahl, 200432 In aLase FS 15 kHz USA 30 −4.66±1.73 (Cus om Co nea) 1 Randomized 3
30 −4.83±1.71 (Zyop ix)
Ja aloy e al, 200733 In aLase FS 15 kHz Spain 100 −3.98±1.89 3 Randomized 4
Chan e al, 200834 In aLase FS 15 kHz USA 51 −3.76±1.41 12 Randomized 3
Du ie and Kezi ian, 200550 In aLase FS 15 kHz USA 51 −3.59 3 Randomized 3
Mon es-Mico e al, 200721 In aLase FS 30 kHz Spain 100 −2.85±1.79 6 Randomized 4
Pa el e al, 200741 In aLase FS 15 kHz USA 21 −4.02±1.61 6 Randomized 3
Munoz e al, 201035 In aLase FS 15 kHz Spain 48 3.98±2.35 (de ocus)a48 Randomized 4
S oneciphe and Kezi ian, 200836 In aLase FS 15 kHz USA 188 – (WF guided) 3 Randomized 1
186 – (WF op imized)
Alio and Pine o, 200831 In aLase FS 30 kHz Spain 22 −4.11±1.10 3 Randomized 5
P ae l e al, 200837 In aLase FS 30 kHz Ge many 287 −4.1±3.6 In aop P ospec i e in e en ional
case s udy
1
Rosa e al, 200938 In aLase FS 60 kHz Po ugal 20 −4.48±2.55 3 P ospec i e coho 1
20 −5.60±1.05
Slade e al, 200913 In aLase FS 60 kHz USA 50 −3.96 6 Randomized 3
P akash e al, 201014 In aLase FS 60 kHz India 60 −5.70 1 Randomized 5
60 −6.09
60 −5.98
60 −5.13
Ha ch e al, 201115 In aLase FS 60 kHz USA 26 −4.34 6 Randomized 5
P akash e al, 201116 In aLase FS 60 kHz India 385 −6.08±2.7 12 Randomized 5
385 −5.99±2.8
He e al, 201417 In aLase FS 60 kHz USA 55 −4.75±2.22 (WF guided) 12 Randomized 3
55 −4.81±1.95 (WF op imized)
Zhai e al, 201339 In aLase FS 60 kHz People’s Republic
o China
59 −7.15±2.87 1 Randomized 4
Tanze e al, 201322 In aLase FS 60 o
150 kHz
USA 544 −2.56 3 P ospec i e noncompa a i e
wo-si e s udy
1
57 −0.34
30 +1.86
Yu and Manche, 201519 In aLase FS 60 kHz USA 61 −4.66±2.30 12 Randomized 3
In aLase FS 150 kHz 61 −4.62±2.32
Sales and Manche, 201323 In aLase FS 150 kHz USA 36 −4.04±1.67 (WF guided) 12 Randomized 3
36 −3.99±1.71 (WF op imized)
Yu and Manche, 201425 In aLase FS 150 kHz USA 50 −3.89±1.67 (Alleg e o Wa e Eye-Q) 12 P ospec i e compa a i e
case se ies
3
50 −4.18±1.73 (Visx S a Cus om ue S4 IR)
V yghem e al, 201026 FEMTO LDV Belgium 111 −4.91±2.45 6 P ospec i e, consecu i e 1
Zhou e al, 201242 FEMTO LDV People’s Republic
o China
360 −6.58±2.86 1 wk Randomized 2
Rosman e al, 201324 Visumax 500 kHz Singapo e 45 −4.94±2.08 3 Randomized 5
In aLase FS 150 kHz 45 −4.91±2.09
Ang e al, 201318 Visumax 500 kHz Singapo e 381 −5.41±2.22 3 Re ospec i e case e iew 1
In aLase FS 60 kHz 362 −5.34±2.28
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Fem osecond lase s o LASIK
Lim e al, 201328 Visumax 200 kHz Ko ea 36 −5.25±1.53 6 Randomized 5
36 −4.89±1.40
Kymionis e al, 201329 Wa eligh AG/Alcon
FS200
G eece 50 −4.15±1.69 6 P ospec i e non andomized
in e en ional case se ies
3
Cummings e al, 201330 Wa eligh FS200 I eland 378 −4.03±2.29 3 Re ospec i e consecu i e
case se ies
1
53 +2.20±1.23
Ahn e al, 201140 In aLase FS 60 kHz Ko ea 50 K=42.37±2.0 2 Compa a i e case se ies 3
Visumax 40 K=43.38±1.77
FEMTO LDV 64 K=43.31±1.48
A belaez e al, 200927 FEMTO LDV Sul ana e o
Oman
50 −3.08±2.32 (de ocus)a6 Re ospec i e 1
No es: aMean mani es de ocus e ac ion as epo ed by he au ho s. S udies w i en in bold ha e been included in he p e iously published me a-analyses.10,11
Abb e ia ions: D, diop e s; LASIK, lase -assis ed in si u ke a omileusis; SD, s anda d de ia ion; SE, e ac i e sphe ical equi alen ; mo, mon hs; WF, wa e on ; wk, weeks; p eop, p eope a i e; in aop, in aope a i e.
Table 2 Pos ope a i e ou come measu es in he s udies included in he me a-analysis o em osecond lase s o LASIK
Re e ences
(au ho , yea )
Su gical p ocedu e P ima y ou comes Seconda y ou comes
Eyes
(n)
E icacy (%) P edic abili y
(%)
Sa e y (%) Eyes
(n)
Ta ge lap
hickness
(µm)
Measu ed lap
hickness (µm) ± SD
( ange)
Me hod In aop
complica ion
(%)
Pos op
complica ion
(%)
T an e al, 2005
20
In aLase FS 10 kHz 7 100 –0 8 120 – – 0 37.5
Du ie and S ahl,
2004
32
In aLase FS 15 kHz 30 93 83 0 30 110 – – – –
30 90 93 0 30 110
Ja aloy e al,
2007
33
In aLase FS 15 kHz 100 80
a
83 1 20 120 130.14±1.70 CM 0 17
Chan e al, 2008
34
In aLase FS 15 kHz 40 98 93 3 51 120 118.7±12.2 SUP 0 28 (,1 mo)
Du ie and
Kezi ian, 2005
50
In aLase FS 15 kHz 51 98 90 –51 118 – – – –
Mon es-Mico
e al, 2007
21
In aLase FS 30 kHz 100 100 98 0 100 120 – – – –
Pa el e al, 2007
41
In aLase FS 15 kHz 21 0.01±0.11
LogMa
(20/20) 90 0.06±0.09
LogMa
(20/15)
21 120 143±16 (110–172) CM 0 0
Munoz e al,
2010
35
In aLase FS 15 kHz 48 85.4 97.9 0 48 120 – – 0 0
S oneciphe and
Kezi ian, 2008
36
In aLase FS 15 kHz 188 93 (WF guided) 93 0 374 100–130 – – – –
186 93 (WF op imized) 94 0
Alio and Pine o,
2008
31
In aLase FS 30 kHz 22 –86.4
a
13.6
a
22 110 115.95±6.22 VHF 0 0
P ae l e al, 2008
37
In aLase FS 30 kHz 287 – – 0 287 100 100.4±13.6 (57–138) OCP 0 2.8
Rosa e al, 2009
38
In aLase FS 60 kHz 20 0.02±0.04
LogMa
––20 120 143.1±18.4 (107.2–172.5) SUP – –
20 0.04±0.03
LogMa
20 120 115.5±12.5
(91.6–147.8)
20 minu es
(Con inued)

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Huh ala e al
Table 2 (Con inued)
Re e ences
(au ho , yea )
Su gical p ocedu e P ima y ou comes Seconda y ou comes
Eyes
(n)
E icacy (%) P edic abili y
(%)
Sa e y (%) Eyes
(n)
Ta ge lap
hickness
(µm)
Measu ed lap
hickness (µm) ± SD
( ange)
Me hod In aop
complica ion
(%)
Pos op
complica ion
(%)
Slade e al, 2009
13
In aLase FS 60 kHz 50 92 – 0 25 100 112±5 (87–118) OCT 0 0
P akash e al,
2010
14
In aLase FS 60 kHz 60 97 91.6 0 60 90 89.97±4.12 OCT 3.3 1.7
60 80 90 0 60 100 99.96±5.30 5 3.3
60 82 91.6 0 60 110 110.01±4.50 6.7 1.7
60 87 93.3 0 60 120 119.26±4.94 3.3 1.7
Ha ch e al, 2011
15
In aLase FS 60 kHz 25 92 88 0 26 90 – – 11.5 23.1
P akash e al,
2011
16
In aLase FS 60 kHz 368 82 95.1 0 368 90 90.1±6.7 (76–102) OCT 0 0
368 81 94.02 0 368 100 100.6±6.9 (85–114) 0 0
He e al, 2014
17
In aLase FS 60 kHz 54 87 80 0 54 105 – (WF guided) SUP 0 0
54 78 72 1.9 54 105 – (WF op imized)
Zhai e al, 2013
39
In aLase FS 60 kHz 59 – – – 59 110 111±3 (104–120) OCT – –
Tanze e al, 2013
22
In aLase FS 60 kHz o
150 kHz
497 98.2 – 0.4 544 – – – 0.2 0.2
48 100 – 0 57 – – –
23
b
95.7
b
– 0
b
30 – – –
Yu and Manche,
2015
19
In aLase FS 60 kHz 61 93 95 2 61 105 – – 0 0
In aLase FS 150 kHz 61 95 90 0 61 105 – – 0 0
Sales and Manche,
2013
23
In aLase FS 150 kHz 34 97 94 0 34 105 – (WF guided) SUP – –
34 97 85 0 34 105 – (WF op imized)
Yu and Manche,
2014
25
In aLase FS 150 kHz 50 97.9 100 0 50 105 – (Alleg e o Wa e
Eye-Q)
SUP – –
50 91.5 92 0 50 105 – (Visx S a Cus om ue
S4 IR)
V yghem e al, 2010
26
FEMTO LDV 111 94.6 95.5 0 111 110 106.68±12.68 (84–149) SUP 17.1 14.4
Zhou e al, 2012
42
FEMTO LDV 360 – – – 360 110 103.95±6.11 OCT – –
Rosman e al,
2013
24
Visumax 500 kHz
In aLase FS 150 kHz
39 79.5 89.7 0 45 115 – SUP 13.3 0
39 82.1 84.6 0 45 110 – 2.2 0
Ang e al, 2013
18
Visumax 500 kHz 381 75.5 86.9 – 381 110–120 – – 2.1 0.3
In aLase FS 60 kHz 362 75.0 87.3 – 362 100–110 – 0.3 0.6
Lim e al, 2013
28
Visumax 200 kHz 36 95.8 100
c
0 36 80 83.46±3.50 (73–95) OCT Only OBL
36 100 97.1 0 36 120 122.93±3.55 (107–131) Only OBL
Kymionis
e al, 2013
29
Wa eligh AG/Alcon
FS200
42 86 86 0 42 105 102.98±6.33 (91–114) OCT 4.8 0
Cummings
e al, 2013
30
Wa eligh FS200 378 83.4 91.0 0.3 431 120 120.23±13.94 (73–176) SOP 0 0
53
b
46.4
b
71.0
b
7.5
b
Ahn e al, 2011
40
In aLase FS 60 kHz 50 – – – 50 110 103.3±13.2 OCT – –
Visumax 40 – – – 40 110 133.9±13.9
FEMTO LDV 64 – – – 64 110 105.8±8.2
A belaez e al, 2009
27
FEMTO LDV 50 84 76
d
0 50 110 – SOP 0 0
No es: –, no epo ed;
a
es ima ed om a igu e;
b
hype opic eyes we e excluded;
c
e ac ion wi hin he ±0.25 D o a ge e ac ion;
d
only as igma ism co ec ion. S udies w i en in bold ha e been included in he p e iously
published me a-analyses.
10,11
Abb e ia ions: CM, con ocal mic oscopy; LASIK, lase -assis ed in si u ke a omileusis; OBL, opaque bubble laye ; OCP, op ical cohe ence pachyme y; OCT, op ical cohe ence omog aphy; SD, s anda d de ia ion; SOP,
sub ac ion online pachyme y, di e ence be ween p eope a i e co neal hickness and he hickness o co neal bed a e lap li ing; SUP, sub ac ion ul asound pachyme y; VHF, e y-high- equency digi al ul asound; WF, wa e
on ; pos op, pos ope a i e; in aop, in aope a i e; mo, mon h.
Clinical Oph halmology 2016:10 submi you manusc ip | www.do ep ess.com
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Figu e 3 P edic abili y, he p opo ion o eyes wi hin ±0.5 D o a ge e ac ion a e FS lase o LASIK.
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Figu e 2 E icacy, he p opo ion o eyes wi hin UDVA $20/20 a e FS lase o LASIK.
Abb e ia ions: χ2, chi-squa e s a is ic; CI, con idence in e al; d , deg ees o eedom; FS, em osecond; LASIK, lase -assis ed in si u ke a omileusis; UDVA, unco ec ed
dis ance isual acui y.
s udied In aLase FS 60 kHz, he a e age SD was 12.4 µm.
Fo FEMTO LDV, he ep oducibili y, he a e age SD was
8.2 µm. Fo Visumax, he a e age SD was 23.3 µm and o
Wa eligh FS200 14.3 µm.
Complica ion a es
Among he di e en In aLase ypes, In aLase FS 10 kHz20 had
no in aope a i e complica ions, bu pos ope a i e complica-
ion a e was 37.5% (one s udy was included; Figu es 6 and 7).
In aLase FS 15 kHz33–35,41 had no in aope a i e complica ions,
bu he a e age pos ope a i e complica ion a e was 18.0%.
In aLase FS 30 kHz31,37 had no in aope a i e complica ions,
while he pe cen age o pos ope a i e complica ion was 2.6%.
In aLase FS 60 kHz13–19 had he a e age in aope a i e and
pos ope a i e complica ion a es o 1.4% and 3.2%, espec-
i ely. In aLase 150 kHz19,24 had he a e age in aope a i e
complica ion a e o 0.9% and pos ope a i e complica ion
a e o 0%. FEMTO LDV26,27 had he a e age in aope a i e
complica ion a e o 11.8%. The pos ope a i e complica ion
a e o FEMTO LDV a e aged 9.9%. Fo Visumax,24,28 in a-
ope a i e and pos ope a i e complica ion a es a e aged 3.3%
and 0.2%, espec i ely. Wa eligh FS20029,30 had he lowes
Clinical Oph halmology 2016:10
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Figu e 5 Co neal lap measu emen s a e FS lase o LASIK.
Abb e ia ions: F, F ac o ; FS, em osecond; LASIK, lase -assis ed in si u ke a omileusis; ns, nonsigni ican ; SD, s anda d de ia ion.
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Figu e 4 Sa e y, he p opo ion o eyes losing wo o mo e Snellen lines o CDVA a e FS lase o LASIK.
Abb e ia ions: CDVA, co ec ed dis ance isual acui y; χ2, chi-squa e s a is ic; CI, con idence in e al; d , deg ees o eedom; FS, em osecond; LASIK, lase -assis ed in si u
ke a omileusis; ns, nonsigni ican .
in aope a i e and pos ope a i e complica ion a es o 0.4%
and 0%, espec i ely.
Discussion
This me a-analysis compa ed di e en ypes o FS lase s o
LASIK. In he li e a u e sea ch, we ound 109 po en ially
ele an abs ac s o e iew, bu only 47 we e sui able o
a ull pape e iew. Addi ionally, we included one s udy33
om he p e iously published me a-analyses.10,11 F om
hese 48 a icles, we excluded 17 pape s based on lacking o
duplica e da a, and he inal analysis included 31 a icles. Fo
p ima y ou come measu es, hype opic eyes we e excluded.
No s udies we e excluded om he analysis due o he low-
quali y sco ing by Jadad e al sys em.12
The di e en FS lase sys ems can be classi ied in o
wo g oups: one g oup is cha ac e ized wi h high pulse
ene gy–low pulse equency (such as In aLase and
Fem ec) and he o he wi h low pulse ene gy–high pulse
equency (such as FEMTO LDV and Wa eligh FS200).7
In he FS lase echnology in he high pulse ene gy–low
pulse equency g oup, pulse ene gies a e in he ange o
1 µJ and epe i ion a es on he o de o kilohe z.7 The
low pulse ene gy–high pulse equency sys em deli e s
only pulse ene gy on he o de o nano-joule and uses
megahe z epe i ion a es.7 F om all FS lase s on he
ma ke , In aLase was he i s in oduced and di e en
In aLase FS ypes (10, 15, 30, 60, and 150 kHz) a e he
mos commonly epo ed.
Clinical Oph halmology 2016:10 submi you manusc ip | www.do ep ess.com
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Figu e 6 In aope a i e complica ions a e FS lase o LASIK.
Abb e ia ions: χ2, chi-squa e s a is ic; CI, con idence in e al; d , deg ees o eedom; FS, em osecond; IO, in aope a i e; LASIK, lase -assis ed in si u ke a omileusis.
The pooled p ima y ou come esul s showed ha he e
was a s a is ically signi ican di e ence in he p opo ion
o eyes wi hin a UDVA o 20/20 o be e (e icacy). Based
on e icacy, In aLase and FEMTO LDV ga e he bes
esul s. The e we e also s a is ically signi ican di e ences
in he mean sphe ical equi alen e ac ion wi hin ±0.5 D
o a ge e ac ion (p edic abili y). Based on p edic abili y,
In aLase ypes FS 15, FS 30, and FS 60 kHz we e he bes .
The e was no s a is ically signi ican di e ence in he loss
o $2 Snellen lines o CDVA (sa e y) be ween di e en
FS lase s.
I was di icul o combine he esul s o andomized con-
olled ials because o di e en ollow-up imes. In he 31
s udies chosen o his me a-analysis, he ollow-up ime was #1
mon h in i e s udies.14,32,37,39,42 The mos commonly epo ed
ollow-up imes we e 3 mon hs ( en s udies) 18,20,22,24,30,31,33,36,38,50
and 6 mon hs (eigh s udies).13,15,21,26–29,41 The ollow-up ime
was $1 yea only in se en cases.16,17,19,23,25,34,35 Long ollow-up
imes should be ecommended o epo ing e ac i e esul s,
especially in con olled andomized s udies. In he me a-
analysis, di e en excime lase choices used in LASIK made
i also mo e di icul o compa e e ac i e esul s. Ano he
d awback o his me a-analysis is ha due o limi ed epo ing,
he esul s we e pooled oge he om s anda d, wa e on -
guided, and wa e on -op imized ea men s, and he e was
no compensa ion o his.
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Figu e 7 Pos ope a i e complica ions a e FS lase o LASIK.
Abb e ia ions: χ2, chi-squa e s a is ic; CI, con idence in e al; d , deg ees o eedom; FS, em osecond; LASIK, lase -assis ed in si u ke a omileusis; PO, pos ope a i e.