3-Year follow-up after Lasik: assessing the risk factors for retreatment

Article (PDF Available)inInternational Ophthalmology 36(1) · May 2015with 139 Reads
DOI: 10.1007/s10792-015-0084-4 · Source: PubMed
Abstract
The purpose of this study was to evaluate the correlation of important risk factors for LASIK retreatment and the retreatment rate. A retrospective cohort study was conducted. Records of patients who underwent LASIK between January 2011 and January 2012 at the Zambrano-Hellion Medical Center, Tec de Monterrey (México), and posteriorly underwent LASIK retreatment were identified and risk factors to receive retreatment were assessed using relative risk. Main outcomes were retreatment rate, risk factors for retreatment, and uncorrected distance visual acuity (UDVA). 482 eyes from 241 patients were available for a 36-month follow-up analysis. 68.5 % had primary myopic LASIK; 37 % were ≤2 diopters (D), 52 % were >2 and <6 D, and 11 % were ≥6 D of myopia. 31.5 % of the eyes had hyperopic LASIK. Retreatment was performed in 6.85 % eyes. Myopia >6 D (RR 4.13), hyperopic refraction (RR 3.18), and age >40 (RR 3.07) were the most important risk factors for retreatment (P = 0.004, P = 0.007, P = 0.006, respectively). UDVA was ≥20/40 in 92.1 % and ≥20/20 in 81.6 % of the retreated eyes and 82 % of the eyes within ±0.50 D of target refraction. Increasing degrees of myopia, followed by hyperopic refraction, and age were the most important associated factors to retreatment. LASIK retreatment was safe and effective.
ORIGINAL PAPER
3-Year follow-up after Lasik: assessing the risk factors
for retreatment
Jorge E. Valdez-Garcı
´
a
.
Julio C. Hernandez-Camarena
.
Rosa Martı
´
nez-Mun
˜
oz
Received: 26 January 2015 / Accepted: 11 May 2015
Ó Springer Science+Business Media Dordrecht 2015
Abstract The purpose of this study was to evaluate
the correlation of important risk factors for LASIK
retreatment and the retreatment rate. A retrospective
cohort study was conducted. Records of patients who
underwent LASIK between January 2011 and January
2012 at the Zambrano-Hellion Medical Center, Tec de
Monterrey (Me
´
xico), and posteriorly underwent
LASIK retreatment were identified and risk factors to
receive retreatment were assessed using relative risk.
Main outcomes were retreatment rate, risk factors for
retreatment, and uncorrected distance visual acuity
(UDVA). 482 eyes from 241 patients were available
for a 36-month follow-up analysis. 68.5 % had primary
myopic LASIK; 37 % were B2 diopters (D), 52 %
were [2 and \6 D, and 11 % were C6 D of myopia.
31.5 % of the eyes had hyperopic LASIK. Retreatment
was performed in 6.85 % eyes. Myopia [6 D (RR
4.13), hyperopic refraction (RR 3.18), and age [40
(RR 3.07) were the most important risk factors for
retreatment (P = 0.004, P = 0.007, P = 0.006,
respectively). UDVA was C20/40 in 92.1 % and
C20/20 in 81.6 % of the retreated eyes and 82 % of
the eyes within ±0.50 D of target refraction. Increas-
ing degrees of myopia, followed by hyperopic refrac-
tion, and age were the most important associated
factors to retreatment. LASIK retreatment was safe and
effective.
Keywords LASIK LASIK retreatment Risk
factors Refractive surgery
Introduction
Although sometimes overlooked by the clinician, the
undercorrection rate is a very important parameter of
quality assurance [13]. High rates may indicate that
changes need to be done to the physician’s nomogram
and will naturally result in a higher number of
unsatisfied patients [3]. Given the high satisfaction
rates of LASIK and the widespread use of the
procedure, it is quite possible that patients have high
expectation. It is therefore important to identify sub-
populations of patients with high risk of undercorrec-
tion. Awareness of belonging to a high-risk group, as
well as the alternative of enhancement and its results,
could create more realistic expectations on the
patients, therefore, reducing anxiety and dissatisfac-
tion. This paper discusses the correlation of some
common, although disputed, risk factors for LASIK
J. E. Valdez-Garcı
´
a(&) J. C. Hernandez-Camarena
Service of Cornea and Refractive Surgery,
Ophthalmology and Visual Sciences Institute, School of
Medicine of the Tecnologico de Monterrey, Morones
Prieto 3000 Pte., Los Doctores, 64710 Monterrey,
Nuevo Leon, Mexico
e-mail: jorge.valdez@itesm.mx
R. Martı
´
nez-Mun
˜
oz
School of Medicine of the Tecnologico de Monterrey,
Monterrey, Mexico
123
Int Ophthalmol
DOI 10.1007/s10792-015-0084-4
retreatment in a Hispanic population with a 3-year
follow-up after the initial LASIK treatment and
reports the results of the enhancement procedures.
Methods
A retrospective analysis was performed on the records
of Hispanic patients who underwent LASIK between
January 2011 and January 2012, at the Zambrano-
Hellion Medical Center, Tec de Monterrey (Monter-
rey, Me
´
xico). The analysis followed the tenets of the
Declaration of Helsinki, and informed consent was
obtained from all patients after details of the procedure
were explained. Inclusion criteria for the initial
treatment were age over 18 years; stable refraction
with spherical component in the range of -10.00 to
?6.50 D, and a cylindrical component between 0.00
and 6.50 D; corrected visual acuity of 20/20 (Snellen
visual acuity chart); and at least 36-month follow-up
after the initial treatment. Patients with keratoconus,
post-LASIK ectasia, previous eye surgery, and eye
trauma were excluded. Patients who underwent
LASIK retreatment during this period were identified
and charts were analyzed.
Retreatment was defined as a second LASIK proce-
dure due to residual refractive error or patients who
were not satisfied with the uncorrected visual acuity due
to regression ([0.5 D between two visits separated by
at least 2 months) or undercorrection (undercorrection
[0.5 D of target refraction the first week after the
primary procedure). Initial LASIK procedures were
performed by the same surgeon using a Technolas-217
Excimer workstation (Technolas Perfect Vision GmbH,
Mu
¨
nchen, Germany) using the standard technique.
Briefly, under topical anesthesia with tetracaine
chlorhydrate 0.5 % (Ponti ofteno, Sophia Ò,Jalisco,
Me
´
xico), the cornea was marked with gentian violet
and a superior hinge was performed using a Hansatome
XP Microkeratome (Bausch & Lomb, Rochester, NY).
When indicated both eyes were operated the same day,
with the refractive target to emmetropia. A 6.0-mm
optical zone was used in every case, with a 120 microns
flap with a superior hinge, and average diameter of
9.5 mm (an 8.5-mm-diameter ring was used in eyes
with mean keratometries [45) was created. Postop-
erative medication consisted on moxifloxacin 0.5 %
ophthalmic solution (Vigamoxi Ò, Alcon Laboratories,
Fort Worth TX, US) every 6 h for 7 days and
fluorometholone 0.1 opthalmic suspension (Flumetol,
Sophia Ò, Jalisco, Me
´
xico) in dose reduction for
2weeks.
The amount of residual refractive error treated was
based on subjective refractive measurements. LASIK
retreatments were done only when the estimated
residual stromal thickness was C300 lm. Enhance-
ment was performed by identifying and lifting the
prior flap using a Fukasaku LASIK spatula. Statistical
analysis was performed with the SPSS software
(version 20.0, IBM Inc., NY, USA) for Windows,
using Relative Risk (RR) and Chi-square test to
determine the association between categorical vari-
ables. Visual acuity was measured using Snellen
´
s
visual acuity chart and then converted to LogMAR for
statistical analysis.
Results
A total of 482 eyes from the records of 241 patients
were available for a 36-month follow-up analysis. One
hundred and fifty patients (62 %) were female and 91
(38 %) were males. The mean age for the primary
intervention was 33.3 (±12.1) years. Patient demo-
graphics and refraction at the time of the primary
treatment are given on Table 1. Three hundred and
thirty eyes (68.5 %) had primary myopic LASIK; 122
eyes (37 %) were B2 D, 172 eyes (52 %) were[2 and
\6 D, and 36 eyes were C6 D of myopia. One
hundred and fifty two eyes (31.5 %) had hyperopic
LASIK. The uncorrected distance visual acuity after
1 year of the primary procedure was C20/40 in 81.1 %
of patients and 20/20 in 72.2 %. Retreatment was
performed in 33 (6.85 %) eyes. The age at the time of
the retreatment was 39.1 (±10.9), 45 % were female.
The mean time between the primary treatment and the
enhancement was 40.5 (±38.2) months, with a mean
follow-up after retreatment of 4.2 (±2.1) months
(Table 2). The mean corneal thickness measured at
retreatment time was 540 ± 30.2 lm. Of the retreated
eyes, 15 (45.5 %) were myopic and 18 (54.5 %)
hyperopic corrections. Of the myopic enhancements,
one eye (6.2 %) had a baseline refraction \-2D,
eight eyes (56.2 %) were between -2 D and -6D,
and six eyes (37.6 %) were initially [-6 D. The
uncorrected distance visual acuity was C20/40 in
92.1 % of the eyes and 20/20 in 81.6 % after 3 months
of the enhancement treatment. Of the retreated eyes,
Int Ophthalmol
123
82 % were within ±0.50 D of the target refraction.
None of the patients lost lines of corrected distance
visual acuity and none of the patients presented
epithelial ingrowth or corneal ectasia at the last
follow-up.
An association between undercorrection and in-
creasing degrees of myopia (P = 0.004) was observed,
with eyes [6 diopters of myopia having four times
more likely to be retreated (RR = 4.13). Hyperopic
refraction had a RR of 3.18 respective to myopia to
receive enhancement (P = 0.007). Of the patients with
an enhancement treatment, 52 % were over 40 years.
Age over 40 years old was also significantly associated
to undercorrection (P = 0.006), and patients in this
age group were three times (RR = 3.07) as likely to get
excimer surgery enhancement (Fig. 1). Post-treatment
visual acuity had no effect on the risk for retreatment
(P = 0.99). There was no gender difference in the risk
for retreatment.
Discussion
Over the past two decades, LASIK has proved to be a
safe, an efficient, and a predictable method to correct
myopia, astigmatism, and hyperopia, though the
results for the latter are generally less predictable
[46]. However, enhancement rates still are high
Table 1 Patient demographics and refraction
Preoperative (n = 482) 1 year postoperative (n = 482)
Gender % (n) Female 62 % (150)
Age (years) 33.3 (±12.1)
UCVA
a
(SD) 0.9 (±0.4)
[20/25]
0.1 (±0.3)
[20/25]
CDVA
a
(SD) 0.0 (±0.1)
[20/20]
0.0 (±0.2)
[20/20]
SE
b
(SD; range) -3.25 (±4.50; ?6.25 to -8.50) -0.50 (±1.50; ?2.25 to -1.50)
CYL
b
(SD; range) -1.75 (±1.50;-0.25 to -5.25) -0.75 (±0.75;-0.25 to -2.25)
UCVA uncorrected distance visual acuity, CDVA corrected distance visual acuity, SE spherical equivalent, CYL refractive cylinder,
SD Standard deviation
a
Expressed in LogMAR/[Snellen]
b
Expressed in diopters (D)
Table 2 Patient demographics and refraction at retreatment and 3 months postoperative
At retreatment (n = 33) 3 months after retreatment (n = 33)
Gender % (n) 45 % (15)
Age (years) 39 (±10.9)
UCVA
a
(SD) 0.2 (±0.3)
[20/30]
0.1 (±0.1)
[20/25]
CDVA
a
(SD) 0.1 (±0.2)
[20/25]
0.09 (±0.1)
[20/25]
SE
b
(SD; range) -0.50 (±1.75; ?2.50 to -1.75) -0.50 (±1.25; ?1.00 to -1.00)
CYL
b
(SD; range) -0.75 (±1.00; -0.25 to -2.25) -0.55 (±0.55; -0.25 to -1.25)
UCVA uncorrected distance visual acuity, CDVA corrected distance visual acuity, SE spherical equivalent, CYL refractive cylinder,
SD Standard deviation
a
Expressed in LogMAR/[Snellen]
b
Expressed in diopters (D)
Int Ophthalmol
123
ranging from 3.8 to 30 % in eyes with high myopia or
hyperopia [710]. Retreatment procedures in an
attempt to eliminate residual refractive error or to
compensate for refractive regression are mostly
encouraged by patient visual dissatisfaction in the
postoperative period. The current study analyzes the
association of the risk factors found in 482 eyes over a
period of 3 years after the primary LASIK to receive
an enhancement treatment or retreatment.
The overall retreatment rate in the current study
was 6.8 %, which is significantly lower than the
reported by other authors for moderate to high myopia
(ranging from 20 to 30 %) [7, 8, 10] or hyperopia
alone (12.8–29 %) [11, 12] and is slightly higher that
the reported by other authors for large cohort of post-
LASIK eyes (Watson et al. and Yuen et al., retreat-
ment rates of 4.9 and 3.8 %, respectively) [5, 13]. The
latter authors explain their low rate of retreatments, as
we also could do so, because of the predominance of
low to moderate refractive error since regression
(especially in myopic eyes) increases with higher
corrections. We found the increasing risk for
retreatment with a baseline hyperopic refraction (RR
3.18), this is in agreement with the findings of
Randleman et al. who concluded that eyes with
hyperopic refractions or astigmatism (C1 D) were
more likely to undergo retreatment [11]. An asso-
ciation between increasing degrees of myopia and
retreatment was also found. In this matter, Saeed et al.
found that baseline degree of myopia was a significant
predictor for regression after both the initial LASIK
and retreatment [14]. This is in agreement with Hersh
et al. who also defined high initial corrections ([6D)
as risk factors for LASIK retreatment [15]. With
regards to age, we found association between older age
([40 years old) and retreatment. In contrast with the
results found in the work of Febbraro et al. and
Randleman et al. who did not find correlation between
age and LASIK retreatment, and in agreement with the
results of Hersh et al. who found patients over 40 years
at greater risk for retreatment [11, 15, 16]. The
retreatment rate was not influenced by the gender, this
is in agreement with the results reported by other
authors [11].
Fig. 1 Risk factors for
LASIK retreatment. a Eyes
with high myopia (C6
diopters) were four times
more likely to be retreated
(RR 4.32, P = 0.004).
b Eyes with hyperopic
refraction were three times
more likely to be retreated
(RR 3.18, P = 0.007).
c Patients over 40 years old
were three times more likely
to be retreated (RR 3.07,
P = 0.004)
Int Ophthalmol
123
The UDVA [Snellen] of the retreated eyes in our
study was 20/40 or better in 92.1 % (30 eyes) and
20/20 or better in 81.6 % (27 eyes), with 82 % of the
eyes within ±0.50 D of the target refraction. These
results reach and agreement with the reports of Saeed
et al. who found and UDVA [Snellen] of 20/30 of
better in 88 % of the eyes and 77 % of the eyes within
±0.50 D of the target refraction, considering that his
analysis was over a 4-year follow-up after retreatment
[14]. Kashani et al. reported a final UCVA [LogMAR]
of 0.06 ± 0.13 (Snellen equivalent 20/22) for myopic
retreatment and 0.06 ± 0.16 (Snellen equivalent
20/22) for hyperopic retreatment after a mean fol-
low-up of 17.7 months [17]. This is in accordance with
the reported UDVA [LogMAR] of 0.1(± 0.1) (Snellen
equivalent 20/25) at an early 3-month follow-up in our
work. Similarly, McAlinden et al. reported the
retreatment results of residual refractive errors with
flap lift LASIK. In this study after a 6-month follow-
up, 73 and 88.3 % of the eyes had an UDVA [Snellen]
of 20/20 and were within ±0.50 D of emmetropia,
respectively [18]. Although it was not the main
purpose of the study, since the follow-up time after
retreatment is short (3 months) and data are insuffi-
cient to assure refractive and visual stability, the short-
term visual outcomes were excellent and comparable
to the reported results of other authors.
One important limitation of this study is absence of
cycloplegic refraction during the postoperative visits
after LASIK; therefore, in the cases of hyperopic
treatments, the analysis of whether the retreatment
were due to regression or to facultative hyperopia.
Finally, larger sample size and longer follow-up will
be necessary for a higher certainty in the visual
outcomes after LASIK enhancement.
In conclusion, our retreatment rate was low
(6.85 %) and as other authors, we can explain this
because of the predominance low to moderate refrac-
tive error in our series. Also, the results suggest that in
our population increasing degrees of myopia, followed
by hyperopic refraction, and age were the most
important associated factors to retreatment. These
risk factors should always be considered when study-
ing a patient who is a candidate for LASIK surgery in
order to set up realistic expectations and to achieve a
proper patient selection, finally improving patient
satisfaction.
Acknowledgments The authors do not report any funding or
grant used in the elaboration of this paper.
Conflict of interest The authors declare that they have no
conflict of interest.
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    To analyze and compare retreatment rates after wavefront-optimized photorefractive keratectomy (PRK) and LASIK and determine risk factors for retreatment. A retrospective chart review was performed to identify patients undergoing PRK or LASIK with the wavefront-optimized WaveLight platform from January 2005 through December 2006 targeted for a piano outcome and to determine the rate and risk factors for retreatment surgery in this population. Eight hundred fifty-five eyes were analyzed, including 70 (8.2%) eyes with hyperopic refractions and 785 (91.8%) eyes with myopic refractions. After initial treatment, 72% of eyes were 20/20 or better and 99.5% were 20/40 or better. To improve uncorrected visual acuity, 54 (6.3%) eyes had retreatments performed. No significant differences in retreatment rates were noted based on age (P = .15), sex (P = .8), eye (P = .3), PRK versus LASIK (P = 1.0), room temperature (P = .1) or humidity (P = .9), and no correlation between retreatment rate and month or season of primary surgery (P = .4). There was no correlation between degree of myopia and retreatment rate. Eyes were significantly more likely to undergo retreatment if they were hyperopic (12.8% vs 6.0%, P = .006) or had astigmatism > or = 1.00 diopter (D) (9.1% vs 5.3%, P = .04). Retreatment rate was 6.3% with the WaveLight ALLEGRETTO WAVE excimer laser. This rate was not influenced by age, sex, corneal characteristics, or environmental factors. Eyes with hyperopic refractions or astigmatism > or = 1.00 D were more likely to undergo retreatment.
  • Article
    To assess the long-term safety, predictability, and efficacy of wavefront-guided laser in situ keratomileusis (LASIK) retreatment in myopes and hyperopes following primary wavefront-guided LASIK. Retrospective nonrandomized case series. Wavefront-guided retreatment was performed by a single surgeon (D.G.). A cohort of 63 eyes of 41 patients were studied, investigating refractive outcome, uncorrected visual acuity (UCVA), and best-corrected visual acuity before and after wavefront-guided LASIK retreatment. The mean spherical equivalent (MSE) prior to primary LASIK in the myopic group (46 eyes) was -5.4 +/- 2.5 diopters (D) (range, -1 to -11.25 D). After the final retreatment the MSE was -0.08 +/- 0.45 D (range, +1.25 to -1.25) with 82.6% achieving +/-0.5 D and 95.6% +/-1 D of emmetropia. The initial MSE in the hyperopic group (17 eyes) was +1.91 +/- 1.13 D (range, +0.25 to +5.73 D). After the final retreatment the MSE was +0.23 +/- 0.43 D (range, -0.5 to +1.25) with 88.2% achieving +/-0.5 D and 100% +/-1 D of emmetropia. Logarithm of the minimal angle of resolution UCVA was 0.22 +/- 0.21 prior to primary LASIK and -0.06 +/- 0.13 after final retreatment for myopes and 0.14 +/- 0.15 prior to primary LASIK and 0.06 +/- 0.16 after final retreatment for hyperopes. The mean follow-up time after LASIK enhancement was 17.75 months in the myopic and 14.6 months in the hyperopic group. Our results suggest that wavefront-guided retreatment following initial wavefront-guided treatment in myopes and hyperopes has favorable outcome with respect to safety, predictability, and efficacy.
  • Article
    Photorefractive keratectomy can cause corneal scarring and visual loss in highly myopic eyes. We evaluated laser in situ keratomileusis (LASIK) because it has the theoretical advantage of preserving both the corneal epithelium and Bowman's layer. In a prospective study, LASIK was performed in 62 myopic eyes (42 patients) using the Automatic Corneal Shaper (Chiron Vision) and the Keracor 116 excimer laser (Chiron Technolas). We measured refraction and visual acuity, and evaluated corneal topography (TMS 1) and corneal clarity after 4 to 8 weeks and 4 to 6 months. Four- to 6-month follow up was completed in 51 eyes. The mean preoperative spherical equivalent refraction was -14.80 diopters (D) (range, -6.00 to -29.00 D). Postoperatively, the mean deviation from the target refraction was -1.70 D (range, -9.00 to +2.50 D) at 4 to 8 weeks and -1.90 D (range, -9.50 to +2.25 D) at 4 to 6 months. At 4 to 6 months, 19 eyes (37%) were within +/- 0.50 D of the target refraction, 24 (47%) within +/- 1.00 D, 33 (65%) within +/- 2.00 D, and 40 (78%) within +/- 3.00 D. From 4 to 8 weeks to 4 to 6 months, the mean regression of myopia was -0.20 D (0.50 D or less in 24 eyes [47%], 1.00 D or less in 32 [63%], and 2.00 D or less in 42 [82%]). In six eyes (12%), the stromal interface was not visible, in 38 (74%) it was barely visible, and in seven (14%) it was clearly visible. Corneal topography revealed only small variations in clear-zone size and dioptric value, demonstrating a very stable correction 4 to 6 months postoperatively. LASIK may be a safe and effective procedure to correct high myopia. Further research is required to develop satisfactory microkeratome technology, effective laser algorithms, and to determine long-term stability of refraction.
  • Article
    To evaluate the effectiveness, predictability, and safety of laser in situ keratomileusis (LASIK) in 143 eyes with myopia from 8.00 to 20.00 diopters (D). Alicante Institute of Ophthalmology, University of Alicante School of Medicine, Alicante, Spain. This prospective study comprised 143 eyes (94 patients) that had LASIK with the Chiron Automated Corneal Shaper and the VISX 20/20 excimer laser using a multizone profile and a sutureless hinged corneal flap technique. Uncorrected visual acuity of 20/40 or better in 45.0% of eyes 3 months postoperatively and in 46.4% at 6 months. Best corrected visual acuity (BCVA) improved by 0.07 at 3 and 6 months and was stable after 3 months. Mean spherical equivalent was -13.19 diopters (D) +/- 2.89 (SD) preoperatively and +0.51 +/- 1.63 D at 3 months and +0.18 +/- 1.66 D at 6 months postoperatively. At 3 months, spherical equivalent was within 1.00 D of emmetropia in 57.5% of all eyes, 71.0% of eyes with a baseline refraction from -8.00 to -11.99 D (n = 59), 44.4% with a baseline refraction from -12.00 to -15.99 D (n = 54), and 53.0% of eyes with a baseline refraction from -16.00 to -20.00 D (n = 30). The respective 6 month percentages were 60.0, 72.4, 46.0, and 50.0%. The regression of effect was similar in all groups (approximately 0.50 D) between 1 and 3 months, although the high myopia group had further regression. Significant corneal steepening and an increase in corneal thickness occurred between 1 and 3 months. Flap thickness was always less than predicted with both the 130 microns plates, and achieved laser ablation was deeper than programmed. The relationships between postoperative refraction and preoperative keratometry and postoperative refraction and the difference in achieved versus programmed ablation were significant. Complications at 6 months included epithelial ingrowth, corneal flap melting, decentered ablation, and irregular astigmatism with loss of BCVA, although none was vision threatening. In this study, LASIK was effective and predictable in the correction of high myopia but was more accurate for myopia up to 12.00 D. Current surgical algorithms must be modified to improve predictability in higher corrections. Longer follow-up is necessary to evaluate long-term incidence of vision-threatening complications.
  • Article
    This study aimed to analyze the results of laser in situ keratomileusis (LASIK) in different degrees of myopia. Three hundred consecutive eyes were divided into 4 groups according to their degree of preoperative myopia. Group I was between -3 and -6 diopters (D) (28 eyes), low myopia. Group II was between -6.25 and -10 D (138 eyes), moderate myopia. Group III was between -10.25 and -15 D (91 eyes), high myopia. Group IV was between -15.25 and -25.50 D (43 eyes), extremely high myopia. Patients were observed for 6 to 25 months. For group I, the preoperative spherical equivalent was -5.12 D +/- 0.81 standard deviation (SD), corrected visual acuity was 0.88 +/- 0.14 (SD), and keratometry was 44.09 D +/- 1.65 (SD). At the last check-up, the spherical equivalent was -0.42 D +/- 0.98 (SD), corrected visual acuity was 0.89 +/- 0.15 (SD), keratometry was 39.11 D +/- 1.61 (SD). For group II, preoperative spherical equivalent was -8.33 D +/- 1.24 (SD), corrected visual acuity was 0.72 +/- 0.22 (SD), keratometry was 44.34 D +/- 1.64 (SD). At last check-up, the spherical equivalent was -0.19 D +/- 1.22 (SD), corrected visual acuity was 0.76 +/- 0.17 (SD), keratometry was 37.56 D +/- 1.90 (SD). For group III, the preoperative spherical equivalent was -12.37 D +/- 1.49 (SD), corrected visual acuity was 0.58 +/- 0.23 (SD), and keratometry was 44.06 D +/- 1.63 (SD). At last check-up, spherical equivalent was -0.55 D +/- 1.63 (SD), corrected visual acuity was 0.61 +/- 0.18 (SD), and keratometry was 35.88 D +/- 2.18 (SD). For group IV, the preoperative spherical equivalent was -19.04 +/- 2.82 (SD), corrected visual acuity was 0.37 +/- 0.17 (SD), and keratometry was 44.02 D +/- 1.30 (SD). At last check-up, spherical equivalent was -1.49 D +/- 1.54 (SD), corrected visual acuity was 0.44 +/- 0.18 (SD), and keratometry was 33.94 D +/- 2.54 (SD). With some exceptions, LASIK results generally are acceptable and stable. Nevertheless, the scatter of some cases shows that there is room for improvement, even in the most sophisticated excimer software. The high regression of group I proves the need to sample multizone software to determine whether stability is improved. Although visual results are better in patients with lower myopia, the patients whose eyes had higher ametropia more often showed improvement in their visual acuity. This may be because of the greater postoperative size of the image on the macula.
  • Article
    To evaluate the results after enhancement of myopic laser in situ keratomileusis (LASIK) using the VISX Star excimer laser. The Buzard Eye Institute, Las Vegas, Nevada, USA. In this prospective study, 52 eyes of 40 patients had LASIK enhancement. The existing flap was lifted and the excimer laser treatment reapplied for the residual refractive error. The VISX Star excimer laser was used for the primary LASIK and the enhancement procedure. Retreatments for undercorrection, regression, and overcorrection were performed after 6 weeks and up to 40 weeks after the primary LASIK. Follow-up was 96% at 1 month, 67% at 6 months, and 71% at 12 months. Mean pre-enhancement spherical equivalent was -0.77 diopters (D) +/- 0.94 (SD) and mean uncorrected visual acuity (UCVA), 20/60. One year after the enhancement, mean spherical equivalent was -0.13 +/- 0.33 D, and mean UCVA was 20/25. Refraction remained stable during the 1 year follow-up, with no treatment required. After the enhancement, all patients had a UCVA of 20/40 or better. At 1 year, 3% of patients had lost 1 line of best corrected visual acuity and 32% had gained 1 line. No epithelial ingrowth was noted. Retreatment for LASIK beginning 6 weeks after the initial procedure proved to be effective with minimal complications and good results. The technique to raise and reposition the flap appeared safe, and complications were few.