Transcript PRK over LASIK – a case series

PRK Enhancement with
Mitomycin - C after LASIK a case series
Dr G.B.Kaye MD,FRCSC
Dr R. Dalvi MS,DNB
Gimbel Eye Centre
Edmonton,Canada
The Authors have no Commercial Interest to declare
INTRODUCTION
Laser in situ keratomileusis (LASIK) is a procedure
commonly used for the correction of ametropia.
Photorefractive Keratectomy (PRK), however, is often
preferred when limited corneal bed thickness is an
issue. In this case series, PRK was performed over
LASIK due to insufficient residual bed depth for a
LASIK enhancement procedure.
PURPOSE
To evaluate the efficacy and safety of PRK
for the treatment of refractive errors which
were residual, or due to regression following
previous LASIK surgery in which
insufficient bed remained for LASIK
enhancement.
MATERIALS & METHODS
In this single center, retrospective, observational case
series, 6 eyes of 5 patients (mean age 46.6 years) were
evaluated that had had PRK for the treatment of residual
refractive error or refractive error due to regression
following previous myopic LASIK surgery. The NIDEK EC
5000 (Gamagori, Japan) was used for the enhancement
procedures. All eyes underwent slit-lamp biomicroscopy,
refraction, pachymetry, pupillometry, and corneal
topography pre- and post-operatively. All eyes were
followed up at 3 days, 1 week, and monthly for 6 months.
Mitomycin-C (0.02%) was used in all cases, immediately
following the PRK procedure.
TECHNIQUE
PRK
The standard technique was used as in the case of PRK enhancements.
The epithelium was removed using a Paton spatula after soaking the
epithelial surface with 50% alcohol for 10 seconds. Care was taken to
scrape the epithelium from the corneal surface in the direction away
from the hinge of the LASIK flap. This was followed by laser treatment
done with the NIDEK EC 5000 laser.
Mitomycin – C (0.02%) was applied to the corneal surface for 30
seconds after completion of the laser treatment.
A bandage contact lens was placed after instillation of Vigamox, FML
0.1% and Voltaren drops. The eyes were seen again on the third post
operative day. All eyes were placed on a tapering schedule of FML 0.1%
drops for 3 to 6 months following the PRK enhancement procedure.
Two eyes had had Intralase LASIK rather than blade LASIK as the
primary procedure.
RESULTS
The mean interval between the LASIK surgery and the
PRK enhancement was 35 months (range: 9 to 84 months).
At 4 months follow-up (post-PRK), the average UCVA had
improved from 20/60(range: 20/25 to 20/125) preoperatively to 20/25(range: 20/20 to 20/40).
Two eyes had grade 1 sub-epithelial haze observed at 2
months postoperatively which resolved spontaneously over
the ensuing months.
One patient (2 eyes) was diabetic but did not show any
post operative complication.
Mean spherical equivalent attempted correction with PRK
was - 2.00 diopters (D) (range: - 1.00 to - 3.1D) which
improved post-operatively to a spherical equivalent of
- 0.61D (range: +0.5 to - 0.87D).
SUMMARIZING TABLE
Initial
Pachymetry
Flap thickness
Post
LASIK
Bed
Depth
Pre
LASIK
Post
LASIK
Post
PRK
SE (D)
SE (D)
SE(D)
Initial
UCVA
Pre PRK
Final
UCVA,
4 months
Post
PRK
Final
BCVA,
4 months
Post
PRK
DF
538 microns
160 microns
268
microns
-7.5
-3.125
-0.67
20/125
20/30
20/20
DF
553 microns
160 microns
263
microns
-6.67
-1.75
-0.25
20/125
20/40
20/20
DG
485 microns
160 microns
223
microns
-5.00
-2.00
-0.87
20/70
20/25
20/15
LH
528 microns
160 microns
237
microns
-7.87
-2.50
1.00
20/40
20/30
20/25
KH
509 microns
110 microns
276
microns
-6.12
-1.00
0.00
20/25
20/20
20/15
SS
532 microns
110 microns
289
microns
-6.87
-1.625
-0.12
20/50
20/30
20/20
CONCLUSION
PRK enhancement with the adjunctive use
of Mitomycin-C (0.02%) is safe for treating
myopic regression and residual refractive
error following previous LASIK. There was
no long term clinically significant haze in
any of the eyes in the study. All eyes showed
improvement in UCVA following the
procedure.
REFERENCES
1 Photorefractive keratectomy retreatment after LASIK.
Neira- Zalentein W , et al. J Refractive Surg 2008
Sep;24(7):710-2
2 Photorefractive keratectomy with 0.02% Mitomycin C for
treatment of residual refractive errors after LASIK. Srinivasan
S,Drake A, Herzig S. J Refractive Surg 2008 Jan;24(1):S64-7
3 Surface ablation after laser in situ keratomileusis: retreatment
on the flap. Beerthuizen JJ, Siebelt E . J Cataract Refractive
Surg 2007 Aug;33(8):1376-80