Transcript Laser-Assisted Subepithelial Keratectomy(LASEK) as a

Laser-Assisted Subepithelial
Keratectomy (LASEK) as a
Treatment for Post-Radial
Keratotomy Hyperopia
Wendy V. Anandajeya, BS
S. A. Erzurum, MD, FRCS
Financial Interest
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Authors acknowledge the financial support of the Polena Trust for Ocular Research at
the St. Elizabeth Development Foundation, Youngstown, Ohio, and David Gemmel,
PhD for manuscript assistance. Statements are the sole responsibility of the authors.
Authors have no financial conflict of interest associated with products described in the
report
Purpose
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Purpose: To demonstrate operative experience
with laser-assisted subepithelial keratectomy
(LASEK) treatment for post-radial keratotomy
hyperopia and describe literature-reported
treatments for this error.
Background
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A common long term complication of RK has included a
hyperopic shift.1 According to the Prospective Evaluation of
Radial Keratotomy study (PERK), 25%-43% of patients
developed hyperopia of 1.00 diopter (D) or more on follow-up
of 0.5 to 10 years postoperatively.2
Numerous treatment modalities have been suggested to correct
for this post-RK hyperopia: pharmacological measures, special
suturing techniques, hyperopic automated lamellar keratoplasty,
photorefractive keratectomy (PRK), and laser in situ
keratomileusis (LASIK).
As far as the authors are aware, no studies have assessed the
safety, efficacy and predictability of LASEK as a treatment
modality for post-RK hyperopia. We describe our operative
experience of LASEK for post-radial keratotomy hyperopia.
Methodology
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Patients and Setting: Five patients with a total of seven eyes had LASEK
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Intervention: LASEK was completed by using an alcohol solution (20%) on
to correct for post-RK hyperopia. All patients underwent LASEK in order to
treat post-RK hyperopic shift. All LASEK procedures were performed at the
same refractive office by the same surgeon. However, previous radial
keratotomy procedures were completed by different surgeons.
the cornea for 40 seconds to create an epithelial flap. After the epithelial flap
was reflected, a VISX Star S4™ laser (Visx Inc., California) was used to
create the ablation and reshape the cornea. The laser was programmed prior
to each procedure for the ablative “cut” based on the patient’s pre-operative
refractive error. Once the laser ablation was completed, the surgeon replaced
the epithelial flap back on the eye and a contact bandage lens was used to
cover the eye and facilitate healing.
Methodology
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Measurements: Preoperatively, corneal curvatures were measured using
keratometry and topography. Visual acuity with and without correction were
evaluated using standard clinical assessments. Visual acuities were tested
using standard BVAT measurements. Patients’ visual acuity was tested
uncorrected and best corrected on each visit. Preoperatively, cycloplegic
refractions were performed on all patients. Postoperatively, manifest
refractions were performed. Results reported were the last achieved
uncorrected and best-corrected visions. Refractions were recorded on each
visit.
Analysis: For standardization and subsequent analysis, visual acuity was
converted to LogMar, and refraction was converted to spherical equivalent.
Descriptive statistics, including mean, standard deviation and SEM were
tabulated for pre- and post-operative visual acuity in LogMar spherical
equivalent and diopter astigmatism. Differences between pre- and post
measurement were analyzed using the two-tailed student’s t test with statistical
significance assumed at α < 0.05. Because bilateral procedures were
conducted in two patients, a sensitivity analysis was conducted in which only
left and only right measurements were retained. When compared to all eye
analysis, statistical decisions for non-independent eye yielded the same results.
Results
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On pre-operative measurement average cycloplegic spherical
equivalent was 1.79 + 1.39 (SEM = 0.53)
On postoperative measurement average manifest spherical
equivalent was 0.14 + 0.74 (SEM = 0.28).
Mean change in spherical equivalent was 1.64 + 1.79 (SEM =
0.67), which was clinically significant (2 tailed paired Student’s t
test = 2.435, p = 0.051).
Preoperative diopter of astigmatism was 1.29 + 0.70 (SEM =
0.26)
Postoperatively, astigmatism was 0.43 + 0.28 (SEM = 0.11).
Mean improvement in diopter of astigmatism was 0.86 + 0.61
(SEM = 0.23), demonstrating statistically significant
improvement (2 tailed paired Student’s t test = 3.718, p = 0.01).
Results
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On pre-operative measurement, average uncorrected LogMar
was 0.32 + 0.09 (SEM = 0.04).
On postoperative measurement, average uncorrected LogMar
measurement, obtained 17.7 months after the procedure (range
4-35 months), improved to 0.07 + 0.10 (SEM = 0.04).
Mean change in Log Mar uncorrected visual acuity, 0.24 + 0.11
(SEM = 0.05), significantly improved (2 tailed paired Student’s t
test = 5.793, p = 0.001). ). When this mean change was analyzed
to account for non-independent eyes the improvement remained
statistically significant (p = 0.01).
Except in two eyes, all Log Mar best corrected acuities were 0.
Both of these patients showed improvement in final, best
corrected visual acuity, with one patient exhibiting improvement
from 0.1 to 0 LogMar and the other patient exhibiting
improvement from 0 to –0.12 LogMar.
Conclusions
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In the current series, LASEK improved all of our patients’ uncorrected visual
acuity and they all maintained best corrected visual acuity.
All patients were spectacle free after their LASEK procedure and had a high
satisfaction level.
Hyperopia and refractive error were reduced in all patients as demonstrated
by improvements in measured diopter.
In all eyes, marked improvement in UCVA was notable in the series -- eyes in
this study reached uncorrected VA of 20/30 of better.
Likewise, LogMar improvement was statistically significant. All eyes of this
study received a postoperative BCVA acuity of 20/20 or better.
All patients were evaluated 1-3 months postoperatively via slip lamp exam and
exhibited clear cornea with no sign of haze or recurrent erosions.
Most patients have also been evaluated on long-term followup, at 2 years, with
sustained visual improvement and no long-term sequelae.
Biography
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Wendy Anandajeya is currently a fourth year medical
student at Northeastern Ohio Universities College of
Medicine (NEOUCOM). She will continue her
ophthalmology training in Washington D.C. at
Georgetown University/Washington National Hospital
starting in 2009.
Dr. Sergul Erzurum is Chief of Ophthalmology in the
Department of Surgery at Forum Health in
Youngstown, Ohio and Professor of Surgery at
NEOUCOM. She is in private practice at Eye Care
Associates in Youngstown, Ohio
References
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