Laser-Assisted Subepithelial Keratectomy (LASEK) as a Treatment for Post-Radial Keratotomy Hyperopia

1
Laser-Assisted Subepithelial Keratectomy (LASEK)
as a Treatment for Post-Radial Keratotomy
Hyperopia

• Wendy V. Anandajeya, BS
• S. A. Erzurum, MD, FRCS

2
Financial Interest

• 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

3
Purpose

• 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.

4
Background

• 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.

5
Methodology

• Patients and Setting Five patients with a total
  of seven eyes had LASEK 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.
• Intervention LASEK was completed by using an
  alcohol solution (20) on 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 patients
  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.

6
Methodology

• 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
  students t test with statistical significance
  assumed at a lt 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.

7
Results

• 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 Students 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 Students t test 3.718, p 0.01).

8
Results

• 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 Students 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.

9
Conclusions

• 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.

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Biography

• 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

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