Docstoc

Corneal flap thickness with the Moria M2 single-use head 90

Document Sample
Corneal flap thickness with the Moria M2 single-use head 90 Powered By Docstoc
					                                                                                       Acta Ophthalmologica Scandinavica 2007




Corneal flap thickness with
the Moria M2 single-use head
90 microkeratome
Anne Huhtala,1,2 Juhani Pietila,1,2 Petri Makinen,1,2 Sakari
                               ¨            ¨
Suominen,1,2 Matti Seppanen1,2 and Hannu Uusitalo2,3
                        ¨

1
  Mehilainen Eye Surgery Clinic, Tampere, Finland
        ¨
2
  Department of Ophthalmology, Medical School, University of Tampere, Tampere,
Finland
3
  Department of Ophthalmology, University of Kuopio and Kuopio University
Hospital, Kuopio, Finland




ABSTRACT.                                                                                         of microkeratome-related flap compli-
Purpose: To analyse the accuracy of corneal flap thickness created in laser-                       cations has been reported to range
assisted in situ keratomileusis (LASIK) using the Moria Model 2 (M2) single-                      from 0.3% to 1.9% (Gimbel et al.
use head 90 microkeratome.                                                                        1998; Tham & Maloney 2000; Jacobs
Methods: The corneal thickness of 300 (266 myopic and 34 hyperopic) eyes of                       & Taravella 2002).
150 patients was measured by ultrasonic pachymetry preoperationally and                              There are a wide variety of micro-
intraoperationally after flap cut. The Moria M2 single-use head 90, intended                       keratomes in clinical use. These
                                                                                                  include the LSK-1, the Carriazo-
to create a flap with a thickness of 120 lm, was used in all eyes. The right
                                                                                                  Barraquer (C-B), and the Model 2
eye was always operated first and the left eye second, using the same blade.
                                                                                                  (M2) (all by Moria SA, Antony,
Results: Mean corneal flap thickness was 115.4 lm (standard deviation [SD]                         France), the Hansatome (Bausch &
12.5) in the two eyes, 115.7 lm (SD 12.4, range 73–147 lm) in right eyes and                      Lomb Surgical, Salt Lake City, UT,
115.1 lm (SD 12.6, range 74–144 lm) in left eyes. Mean horizontal flap                             USA), the Chiron automated corneal
diameter was 9.1 mm (SD 0.2) and mean hinge length 4.1 mm (SD 0.1). There                         shaper (ACS; Bausch & Lomb), the
were no free flaps, incomplete flaps or flaps with buttonholes in the study.                         Summit Krumeich Barraquer micro-
Occasional iron particles were observed in three (1.0%) eyes.                                     keratome (SKBM; Alcon Laborator-
Conclusions: As with most microkeratomes, the single-use head 90 microkera-                       ies, Forth Worth, TX, USA), the
tome cut thinner flaps than were intended. The range of the cuts was relatively                    Nidek MK-2000 (Nidek, Gamagori,
wide. However, thin flaps did not increase the rate of flap-related complica-                       Japan) and the Amadeus (Advanced
tions. The difference between the first and second eyes was not significant.                        Medical Optics, Santa Ana, CA,
                                                                                                  USA). The most common feature of
Key words: laser-assisted in situ keratomileusis – LASIK – microkeratome – single use – corneal   different microkeratomes is that the
flap thickness                                                                                     flap thickness achieved is thinner than
                                                                                                  that intended (Shemesh et al. 2002;
Acta Ophthalmol. Scand. 2007: 85: 401–406
                                                                                                  Spadea et al. 2002; Flanagan & Binder
ª 2006 The Authors
                                                                                                  2003; Pietila et al. 2005). An exception
                                                                                                               ¨
Journal compilation ª 2006 Acta Ophthalmol Scand                                                  is the Amadeus, which tends to cut
                                                                                                  thicker flaps than intended (Jackson
doi: 10.1111/j.1600-0420.2006.00838.x
                                                                                                  et al. 2003). Differences between the
                                                                                                  first (primary) and second (fellow) eye
                                                   Leaming 2003, 2005). The first step in          operated with the same blade have also
                                                   LASIK, the creation of a hinged cor-           been reported (Gailitis & Lagzdins
Introduction                                       neal flap with a microkeratome, is cri-         2002; Shemesh et al. 2002, 2004).
Laser-assisted in situ keratomileusis              tical (Wilson 1998; Ambrosio &                    The recently developed single-
(LASIK) is the most popular proce-                 Wilson 2001). In some LASIK studies            use head microkeratomes have sev-
dure in refractive surgery (Duffey &               evaluating ‡ 1000 eyes, the incidence          eral advantages compared with the


                                                                                                                                      401
Acta Ophthalmologica Scandinavica 2007


traditional metallic heads, such as lack   unit (Moria SA) was used to create              Results
of assembly requirements and trans-        corneal flaps in all eyes. This is a
parency (Pietila et al. 2006). In the
                ¨                          plastic single-use head 90 microkera-           The demographic characteristics of
present study, the accuracy of corneal     tome, designed to create a 120-lm               the 300 eyes (150 patients) that under-
flap dimensions created by the auto-        flap. The right eye was always oper-             went LASIK are presented in Table 1.
mated, plastic single-use head 90          ated first and the left eye second,              Preoperative     spherical    equivalent
Moria M2 microkeratome, designed           using the same blade. The suction               refraction varied from ) 14.00 D to
to create a thin 120-lm flap, was           ring was chosen according to the                + 5.75 D. The study included 266
evaluated in 300 operated eyes.            manufacturer’s       recommendations            myopic and 34 hyperopic eyes. Mean
                                           (nomogram) based on the keratomet-              spherical equivalent refraction in myo-
                                           ric value K1. After creation of a               pic eyes was ) 5.04 D (SD 2.26); that
                                           hinged flap, flap thickness was calcu-            in hyperopic eyes was + 2.67 D (SD
Materials and Methods                      lated by subtracting the remaining              1.49). Mean preoperative keratometric
Pre- and postoperative examinations        central stromal bed thickness from              K1 value was 44.42 D (SD 1.54, range
                                           the preoperative total central corneal          40.98–48.31 D). Mean preoperative
A total of 150 consecutive patients                                                        keratometric K2 was 43.46 D (SD
                                           thickness. Stromal thickness was
with no earlier refractive operations                                                      1.48, range 40.11–47.41 D). Mean
                                           measured immediately after flap cut.
underwent LASIK at Mehilainen Eye
                               ¨                                                           horizontal white-to-white distance of
                                           No moistening drops were used to
Surgery Clinic (Tampere, Finland)                                                          the eyes was 11.6 mm (SD 0.4, range
                                           obtain pachymetry readings. The
between September 2004 and Febru-                                                          10.5)12.6 mm). Mean preoperative
                                           horizontal white-to-white distance of
ary 2005. Mean patient age was                                                             corneal thickness was 548.9 lm (SD
                                           the eye, flap diameter and hinge
34.7 years (SD 10.7, range 18)63                                                           32.0, range 458)653 lm). The fre-
                                           length were measured using a stand-
years. All patients underwent a com-                                                       quency distribution of preoperative
                                           ard calliper. The stromal bed was
plete preoperative ophthalmological                                                        corneal thickness is presented in
                                           ablated using the Meditec MEL80
examination including biomicroscopy,                                                       Fig. 1.
                                           G-scan excimer laser (Carl Zeiss-
measurement of corneal topography                                                             The postoperative characteristics of
                                           Meditec, Jena, Germany).
(TMS 2 upgraded; Computed Anat-                                                            the 300 eyes operated with the Moria
omy Inc., New York, NY, USA),                                                              M2 single-use head 90 microkeratome
                                           Statistical analysis
determination of refraction, measure-                                                      are shown in Table 2. Attempted cor-
ment of uncorrected (UCVA) and best        The mean values and standard devia-
                                           tions of corneal thickness, flap thick-          neal flap thickness was 120 lm; actual
spectacle-corrected visual acuity (BSC-                                                    flap thickness averaged 115.4 lm (SD
VA), measurement of intraocular pres-      ness, flap horizontal diameter and
                                           hinge length in 300 eyes were calcu-            12.5, range 73–147 lm). The fre-
sure (Topcon computerized tonometer                                                        quency distribution of flap thickness
CT-60; Topcon Corp., Tokyo, Japan),        lated. To determine the keratometric
                                           power K in the hinge direction, the             for 300 eyes is shown in Fig. 2. The
and wavefront analysis (WASCA;                                                             mean value in right eyes (operated
Asclepion-Meditec AG, Jena, Ger-           angle between the hinge and K2 was
                                           determined    and     the    difference         first) was 115.7 lm (SD 12.4); that in
many). Preoperative central corneal                                                        left eyes was 115.1 lm (SD 12.6). The
thickness was measured with ultra-         between K1 and K2 calculated. Kera-
                                           tometric power value was assumed                difference between right and left eyes
sonic pachymetry (CILCO Inc., Hunt-                                                        was      not   statistically  significant
ington, WV, USA) operating at a            to change linearly from K1 to K2.
                                           Thus, the K-value in hinge direction            (p > 0.05). Horizontal flap diameter
speed of sound of 1623 m ⁄ second.                                                         ranged from 8.6 mm to 9.6 mm. The
The pachymetry was calibrated before       was determined with the following
                                           equation:                                       mean flap diameter for both right and
each new patient.                                                                          left eyes was 9.1 mm (SD 0.2). Hinge
   Prior to the surgery, topical anaes-    Khinge ¼K2 þðK1 ÀK2 Þ                           length ranged from 3.4 mm to
thetic oxybuprocain hydrochloride                                                          4.5 mm. The mean hinge length in
                                                  Âðangle betweenK2 andhinge=90Þ
(Oftan Obucain; Santen Oy, Tampere,                                                        right eyes was 4.1 mm (SD 0.1); that
Finland) was instilled into the operated                                            ð1Þ
                                                                                           in left eyes was 4.1 mm (SD 0.2).
eyes. After the operation, 3% ofloxacin
solution (Exocin; Allergan, Eastport,
Co. Mayo, Ireland) and 1% diclofenac       Table 1. Characteristics of 300 eyes operated with the Moria M2 single-use head 90 microkera-
solution (Voltaren Ophtha; Novartis,       tome.
Copenhagen, Denmark) were applied.
Over the following 7 days, 1% dexa-        Demographic                                                     Mean                  (SD)
methason-2% chloramphenicol solu-          Patient age (years)                                               34.7                (10.7)
tion (Oftan Dexa-chlora; Santen Oy)        Spherical equivalent refraction (D)
was tapered from five times to twice           Myopic eyes (n ¼ 266)                                        ) 5.04                 (2.26)
daily. One month after surgery, UCVA,         Hyperopic eyes (n ¼ 34)                                      + 2.67                 (1.49)
BSCVA and refraction were measured.        Preoperative keratometric K1 power (D)                           44.42                 (1.54)
                                           Preoperative keratometric K2 power (D)                           43.46                 (1.48)
Microkeratome and surgical techniques      Mean preoperative keratometric power (D)                         43.94                 (1.47)
                                           Horizontal white-to-white distance of the eye (mm)               11.6                  (0.4)
The Moria M2 microkeratome with
the ME-LSK evolution 2 control             SD ¼ standard deviation.



402
                                                                                                                          Acta Ophthalmologica Scandinavica 2007


                             120                                                                                                    patients). The number of eyes within
                                                               99                                                                   ± 0.50 D of target refraction 4 weeks
                             100
                                                                                                                                    after LASIK was 244 (92.4%) in the
                              80                                          72                                                        myopia group and 33 (97.1%) in the
                No of eyes



                                                                                                                                    hyperopia group. After 1 month,
                              60                                                    49
                                                      46                                                                            97.3% of myopic eyes achieved
                              40                                                                                                    UCVA ‡ 20 ⁄ 40 (Table 3). The corres-
                                               15                                         14                                        ponding percentage for hyperopic eyes
                              20
                                     3                                                                1          1                  was 88.2%. Mean BSCVA improved
                               0                                                                                                    slightly compared with baseline val-
                                    451- 476- 501- 526- 551- 576- 601- 626- 651-                                                    ues. The change in BSCVA at
                                    475 500 525 550 575 600 625 650 675                                                             1 month is presented in Fig. 3. None
                                                               Pachymetry (µm)                                                      of the eyes lost ‡ 2 Snellen lines. One
                                                                                                                                    (0.4%) myopic eye gained 2 lines and
Fig. 1. Frequency distribution of preoperative corneal thickness (pachymetry, lm) for 300 eyes
                                                                                                                                    68 (25.8%) myopic eyes gained 1 line.
operated with the Moria M2 single-use head 90 microkeratome.
                                                                                                                                    Two (5.9%) hyperopic eyes gained 1
                                                                                                                                    line. In 205 eyes (68.3% of all eyes),
                                                                                                                                    no changes were noted in Snellen lines
Table 2. Characteristics of 300 eyes operated with the Moria M2 single-use head 90 microkera-
                                                                                                                                    for BSCVA.
tome.
                                                                                                                                       Preoperative spherical equivalent
Demographic                                                                                   Mean                         (SD)     refraction did not correlate with pre-
                                                                                                                                    operative corneal thickness (r ¼
Preoperative corneal thickness (pachymetry, lm)                                               548.9                        (32.0)
                                                                                                                                    ) 0.040, all operated eyes) (Fig. 4).
Flap thickness both eyes (lm)                                                                 115.4                        (12.5)
Flap thickness right eyes (lm)                                                                115.7                        (12.4)   Table 4 shows the correlation coeffi-
Flap thickness left eyes (lm)                                                                 115.1                        (12.6)   cients of the main variables versus flap
Horizontal flap diameter (mm)                                                                    9.1                         (0.2)   thickness. Figure 5 shows the negative
Hinge length (mm)                                                                               4.1                         (0.1)   correlation of patient age and corneal
                                                                                                                                    flap        thickness       (r ¼ ) 0.194,
SD ¼ standard deviation.
                                                                                                                                    p < 0.001). The younger the patient,
                                                                                                                                    the thicker the flap. Figure 6 shows
                                                                                                                                    the relationship between preoperative
                             100
                                                                               87                                                   corneal thickness and flap thickness in
                                                                                         81
                              80                                    72                                                              the right (operated first) and left
                                                                                                                                    (operated second) eyes. It demon-
                No of eyes




                              60
                                                                                                                                    strates that the thicker the cornea, the
                              40                                                                                                    thicker the flap. There were no differ-
                                                        25                                         22                               ences between right eyes (r ¼ 0.576,
                              20
                                     2
                                               6                                                                 5                  p < 0.0001) and left eyes (r ¼ 0.536,
                               0                                                                                                    p < 0.0001). Figure 7 (A, B) shows
                                   71-80   81-90    91-100 101-110 111-120 121-130 131-140 141-150                                  the relationship between preoperative
                                                               Flap thickness (µm)                                                  keratometric power K1 and corneal
                                                                                                                                    flap thickness. In myopic eyes, flap
Fig. 2. Frequency distribution of corneal flap thickness (lm) for 300 eyes operated with the
                                                                                                                                    thickness was not correlated with
Moria M2 single-use head 90 microkeratome. Intended thickness was 120 lm.
                                                                                                                                    keratometric power K1 (r ¼ ) 0.039),
                                                                                                                                    but in hyperopic eyes increasing flap
Table 3. Uncorrected visual acuity preoperatively and 1 month after LASIK.                                                          thickness was associated with flatter
                                           Myopic eyes                                        Hyperopic eyes                        keratometric power K1 (r ¼ ) 0.530;
                                                                                                                                    p < 0.01). A similar relationship was
                                           Baseline                 1 month                   Baseline               1 month        noted between preoperative kerato-
                                                                                                                                    metric power K2 and corneal flap
Visual acuity                              n          (%)           n          (%)            n         (%)          n     (%)
                                                                                                                                    thickness (myopic eyes r ¼ ) 0.015,
20 ⁄ 20                                      0                      210        (79.5)          0                     18    (52.9)   hyperopic eyes r ¼ ) 0.449; p <
< 20 ⁄ 20 but ‡ 20 ⁄ 40                      2         (0.8)         47        (17.8)          7        (20.6)       12    (35.3)   0.01), mean preoperative keratometric
< 20 ⁄ 40 but ‡ 20 ⁄ 100                    21         (7.9)          7         (2.7)         22        (64.7)        4    (11.8)   power K and corneal flap thickness
< 20 ⁄ 100 but ‡ 20 ⁄ 200                   14         (5.3)          0                        3         (8.8)        0             (myopic eyes r ¼ ) 0.028, hyperopic
< 20 ⁄ 200                                 229        (86.1)          0                        2         (5.9)        0
                                                                                                                                    eyes r ¼ ) 0.499; p < 0.01) and preo-
                                                                                                                                    perative keratometric power K in
                                                                                                                                    hinge direction and corneal flap thick-
   There were no free or incomplete                                      Refractive, UCVA and BSCVA out-                            ness (myopic eyes r ¼ ) 0.029, hyper-
flaps, or flaps with buttonholes in the                                    comes 1 month after LASIK with the                         opic eyes r ¼ ) 0.393; p < 0.05).
study. Occasional iron particles were                                    Meditec MEL80 G-scan excimer laser                            Increasing corneal flap diameter cor-
observed in three (1.0%) eyes.                                           were available for 298 eyes (149                           related significantly with preoperative


                                                                                                                                                                        403
Acta Ophthalmologica Scandinavica 2007


                               100                                                                                         is important in LASIK surgery. Thus,
                                                                30
                                                                                                                           establishing corneal flap thickness and
                                80
                                                          175                                                              predicting its variations both play sig-
             % of eyes

                                60                                                                Myopia                   nificant roles in LASIK surgery. The
                                     n = number of eyes                                                                    flap thickness created with different
                                                                                                  Hyperopia
                                40
                                                                          68                                               microkeratomes has been shown to
                                20                                                                                         vary from intended values (Pietila     ¨
                                               20 2                            2
                                                                                        1                                  et al. 2005). Undercutting (i.e. cutting
                                 0                                                                                         corneal flaps that are thinner than
                                       -2        -1       0         +1                  +2
                                                Change in Snellen lines
                                                                                                                           intended) appears to be the most com-
                                                                                                                           mon problem with most microkera-
Fig. 3. Change in best spectacle-corrected visual acuity 1 month after LASIK, in myopic and                                tomes (Flanagan & Binder 2003;
hyperopic eyes.                                                                                                            Pietila et al. 2005, 2006) other than
                                                                                                                                  ¨
                                                                                                                           the Amadeus (Jackson et al. 2003),
                                                                                                                           which tends to cut thicker flaps than
                                                                                                                           intended. In this study, the Moria M2
                               640
                                                                                                                           automated single-use head 90 micro-
             Pachymetry (µm)




                               590                                                                                         keratome, designed to achieve a cor-
                                                                                                                           neal thickness of 120 lm, was used in
                               540                                                                                         all 300 operated eyes. The results with
                                                                                                                           the M2 microkeratome averaged
                               490                                                                                         115.4 lm (SD 12.5). Flap thickness
                                                                                                                           ranged from 73 lm to 147 lm. Thin
                               440
                                 -14     -12   -10    -8   -6    -4    -2     0               2     4       6              flaps are prone to buttonholes and
                                                      Equivalent refraction (D)                                            necessitate more complicated handling
                                                                                                                           during surgery. However, in this
Fig. 4. Preoperative spherical equivalent refraction (D) and preoperative corneal thickness                                study, incomplete flaps, buttonholes
(pachymetry, lm), r ¼ ) 0.040.                                                                                             and other microkeratome-related com-
                                                                                                                           plications were not observed. The
                                                                                                                           standard deviation was relatively
Table 4. Correlation coefficients of variables versus flap thickness in 300 eyes operated with the                           small. Thick flaps can prevent appro-
Moria M2 single-use head 90.                                                                                               priate laser ablation. In the present
                                                                                                                           study, extraordinarily thick flaps,
Variable                                       Mean             (SD)               Correlation coefficient       p-value
                                                                                                                           which may significantly reduce the
Equivalent refraction (D)                      ) 4.16            (3.28)            ) 0.076                      NS         thickness of the stromal tissue avail-
  Myopic eyes                                  ) 5.04            (2.26)            ) 0.052                      NS         able for laser ablation, were not cre-
  Hyperopic eyes                               + 2.67            (1.49)            ) 0.067                      NS         ated. Only in a few cases was the
Corneal thickness (lm)                         548.94           (32.02)              0.555                      < 0.0001   thickness of the remaining untouched
  Myopic eyes                                  549.07           (32.13)              0.567                      < 0.0001   stromal bed < 300 lm. Usually, in
  Hyperopic eyes                               547.91           (31.54)              0.470                      < 0.01
                                                                                                                           the case of an unexpectedly thick flap,
Age (years)                                     34.69           (10.68)            ) 0.194                      < 0.001
  Myopic eyes                                   33.06            (9.45)            ) 0.211                      < 0.001
                                                                                                                           the size of the ablation is adjusted
  Hyperopic eyes                                47.47           (11.23)            ) 0.054                      NS         accordingly to a smaller depth. In the
K1 keratometry (D)                              44.42            (1.54)            ) 0.083                      NS         case of an exceptionally thick flap,
  Myopic eyes                                   44.55            (1.50)            ) 0.039                      NS         which occurs very rarely, the proce-
  Hyperopic eyes                                43.44            (1.51)            ) 0.530                      < 0.01     dure is aborted.
Flap diameter (mm)                               9.09            (0.17)              0.040                      NS            In the present study, thinner flaps
  Myopic eyes                                    9.09            (0.17)              0.062                      NS         (up to 73 lm) were created. It should
  Hyperopic eyes                                 9.04            (0.12)            ) 0.256                      NS
                                                                                                                           be noted that surgeons must be as
Hinge length (mm)                                4.06            (0.15)              0.091                      NS
  Myopic eyes                                    4.06            (0.15)              0.113                      NS         cautious of creating ultra-thin flaps,
  Hyperopic eyes                                 4.07            (0.10)            ) 0.129                      NS         which may cause problems in the lift-
                                                                                                                           ing and repositioning of the flap, as
SD ¼ standard deviation, NS ¼ not significant.                                                                              they are of thicker flaps. Flap thick-
                                                                                                                           ness correlated positively with corneal
                                                                                                                           thickness, as has been shown in our
corneal thickness in myopic eyes (r ¼                                                                                      earlier studies with the Moria M2
0.229, p < 0.001), but not in hypero-
                                                                       Discussion                                          metallic reusable head 130 microkera-
pic eyes (r ¼ ) 0.111, p > 0.05).                                      One of the possible longterm compli-                tome (Pietila et al. 2005, 2006) and
                                                                                                                                         ¨
Similarly, increasing hinge length was                                 cations in corneal surgery is postoper-             the plastic single-use head 130 micro-
associated with thicker corneas in                                     ative keratectasia. Therefore, keeping              keratome (Pietila et al. 2006).
                                                                                                                                            ¨
myopic eyes (r ¼ 0.216, p < 0.001),                                    the thickness of the corneal flap as                    Another common feature of micro-
but not in hyperopic eyes (r ¼ 0.273,                                  thin as possible and thus the thickness             keratomes concerns the difference that
p > 0.05).                                                             of the corneal bed as thick as possible             emerges between the first and second


404
                                                                                                    Acta Ophthalmologica Scandinavica 2007


                                    150                                                                    115.7 lm (SD 12.4) in right eyes and
             Flap thickness (µm)    140                                                                    115.1 lm (SD 12.6) in left eyes.
                                    130                                                                       A common source of serious com-
                                    120                                                                    plications is use of the microkeratome
                                    110                                                                    after improper assembly, which per-
                                    100                                                                    tains to the use of reusable metallic
                                     90                                                                    microkeratomes (Ambrosio & Wilson
                                     80                                                                    2001). The single-use microkeratome
                                     70                                                                    eliminates this problem because it
                                       18        28          38        48            58        68
                                                              Age (years)
                                                                                                           does not need any assembly. Due to
                                                                                                           its transparency, the plastic head pro-
Fig. 5. Patient age (years) and corneal flap thickness (lm), r ¼ ) 0.194, p < 0.001 (all eyes).             vides the surgeon with a better view
The younger the patient, the thicker the flap.                                                              of the operated eye than a metallic
                                                                                                           head does. In larger scale clinical
                                                                                                           practice, single-use heads have the
                                                                                                           potential to minimize the risk of infec-
                                    150                                                                    tion related to reusable microkera-
             Flap thickness (µm)




                                    140                                                                    tomes (Wilson 1998; Ambrosio &
                                    130                                                                    Wilson 2001; Jacobs & Taravella
                                    120                                                                    2002).
                                    110                                                                       The benefits of a thicker stromal
                                    100                                                                    bed and the potential technical pro-
                                     90                                                                    blems with ultra-thin flaps should be
                                     80
                                                                                                           taken into consideration when select-
                                     70
                                      440 460 480 500 520 540 560 580 600 620 640 660                      ing a microkeratome. In the hands of
                                                    Corneal thickness (µm)                                 an experienced surgeon, treatment
                                                                                                           with the Moria M2 single-use head 90
Fig. 6. Preoperative corneal thickness (measured by ultrasonic pachymetry, lm) and corneal                 microkeratome is a safe procedure, as
flap thickness (lm) right eyes (•) r ¼ 0.576, p < 0.0001; left eyes (s): r ¼ 0.536, p < 0.0001.             shown in this study, in which no
                                                                                                           incomplete flaps, buttonholes or other
                                                                                                           microkeratome-related complications
                                                                                                           were found.
                                    150
              Flap thickness (µm)




                                    140
                                    130
                                    120
                                    110                                                                    References
                                    100
                                     90                                                                    Ambrosio R, Jr. & Wilson SE (2001):
                                     80                                                                      Complications of laser in situ keratomi-
                                     70                                                                      leusis: etiology, prevention, and treatment.
                                       40        42           44        46           48        50            J Refract Surg 17: 350–379.
             (A)                                           K1 Keratometry (D)                              Arbelaez MC (2002): Nidek MK 2000 micro-
                                                                                                             keratome clinical evaluation. J Refract
                                                                                                             Surg 18: 357–360.
                                    150                                                                    Duffey RJ & Leaming D (2003): US trends
             Flap thickness (µm)




                                    140                                                                      in refractive surgery: 2002 ISRS Survey. J
                                    130                                                                      Refract Surg 19: 357–363.
                                    120                                                                    Duffey RJ & Leaming D (2005): US trends
                                    110                                                                      in refractive surgery: 2003 ISRS ⁄ AAO
                                    100                                                                      survey. J Refract Surg 21: 87–91.
                                     90                                                                    Flanagan GW & Binder PS (2003): Precision
                                     80                                                                      of flap measurements for laser in situ kera-
                                     70                                                                      tomileusis in 4428 eyes. J Refract Surg 19:
                                       40   41        42    43     44    45     46        47   48            113–123.
            (B)                                            K1 Keratometry (D)                              Gailitis RP & Lagzdins M (2002): Factors
                                                                                                             that affect corneal flap thickness with the
Fig. 7. (A) Keratometric power K1 (D) and corneal flap thickness in myopic eyes (lm), r ¼                     Hansatome microkeratome. J Refract Surg
) 0.039. (B) Keratometric power K1 (D) and corneal flap thickness in hyperopic eyes (lm),                     18: 439–443.
r ¼ ) 0.530, p ¼ 0.0013.                                                                                   Gimbel HV, Penno EE, van Westenbrugge
                                                                                                             JA, Ferensowicz M & Furlong MT (1998):
                                                                                                             Incidence and management of intraopera-
                                                                                                             tive and early postoperative complications
eyes when the same blade is used for                              study of the Moria M2 single-use           in 1000 consecutive laser in situ keratomi-
both eyes (Arbelaez 2002; Shemesh                                 head 90, this difference was insignifi-     leusis cases. Ophthalmology 105: 1839–
et al. 2002, 2004). However, in this                              cant: mean corneal flap thickness was       1847.



                                                                                                                                                    405
Acta Ophthalmologica Scandinavica 2007


Jackson DW, Wang L & Koch DD (2003):             Shemesh G, Dotan G & Lipshitz I (2002):           Wilson SE (1998): LASIK: management of
  Accuracy and precision of the Amadeus            Predictability of corneal flap thickness in       common complications. Laser in situ ker-
  microkeratome in producing LASIK flaps.           laser in situ keratomileusis using three dif-    atomileusis. Cornea 17: 459–467.
  Cornea 22: 504–507.                              ferent microkeratomes. J Refract Surg 18:
Jacobs JM & Taravella MJ (2002): Incidence         S347–S351.
  of intraoperative flap complications in laser   Shemesh G, Leibovitch I & Lipshitz I (2004):
  in situ keratomileusis. J Cataract Refract       Comparison of corneal flap thickness             Received on July 6th, 2006.
  Surg 28: 23–28.                                  between primary and fellow eyes using           Accepted on September 22nd, 2006.
Pietila J, Makinen P, Suominen S, Huhtala A
      ¨     ¨                                      three microkeratomes. J Refract Surg 20:
  & Uusitalo H (2005): Corneal flap mea-            417–421.                                        Correspondence:
  surements in laser in situ keratomileusis      Spadea L, Cerrone L, Necozione S & Bales-         Dr Anne Huhtala
  using the Moria M2 automated microkera-          trazzi E (2002): Flap measurements with         Medical School
  tome. J Refract Surg 21: 377–385.                the Hansatome microkeratome. J Refract          University of Tampere
Pietila J, Makinen P, Suominen S, Huhtala A
        ¨     ¨                                    Surg 18: 149–154.                               FIN-33014 University of Tampere
  & Uusitalo H (2006): Bilateral comparison      Tham VM & Maloney RK (2000): Micro-               Finland
  of corneal flap dimensions with the Moria         keratome complications of laser in situ         Tel: + 358 3 3551 7977
  M2 reusable head and single-use head micro-      keratomileusis. Ophthalmology 107: 920–         Fax: + 358 3 3551 6170
  keratomes. J Refract Surg 22: 354–357.           924.                                            Email: Anne.Huhtala@uta.fi




406

				
DOCUMENT INFO