ABSTRACT Background : Corneal wound healing
and tissue response have been known to have an effect on the outcome in refractive
procedures when comparing different refractive surgical modalities performed in different
subjects. The purpose of this study was to compare the visual outcome, refraction and
stability in the same subjects who were treated with excimer PRK in one eye and LASIK in
the other.
Methods : Twelve subjects treated with excimer
PRK in one eye and LASIK in the other for myopic correction were reviewed. Ten eyes in PRK
group were treated with Aesculap-Meditec, MEL 60 Excimer Laser and the other two with
Omnimed UV 200 LA Summit Excimer Laser. The Chiron automate microkeratome had been used to
create a corneal flap and the Aesculap-Meditec, MEL 60 was applied for remodeling over the
corneal bed in all LASIK treated eyes.
Results: PRK series : Five eyes (41.7%) had a
myopic regression with the spherical equivalent refraction over - 2.0 D after first
treatment and 4 eyes were retreated. One eye (8.3%) developed marked haze (grade 3) and
loss of two lines of best corrected visual acuity.
LASIK series Eleven eyes (91.7%) achieved an uncorrected visual
acuity of 20/40 or better by 1 month after surgery and this degree of visual acuity was
maintained or improve at least 12 months after treatment. Two eyes were retreated due to
initial overcorrection. Loss of two or more lines did not occur in any eye.
Conclusion LASIK seemed to be superior to PRK
by using lamellar keratectomy to gain access the corneal stroma with anterior corneal flap
and keep intact central Bowman's layer accompanied with the precision of the excimer laser
ablation. Optimal visual result was obtained with rapid recovery. The post operative
spherical equivalent refraction in LASIK group appeared to be nearly stable one month
after the procedure in low myopic eye and had a minor change since 2 months after
treatment in myopia over-6.0 D. Furthermore LASIK reduced or eliminated the problem
concerning severe pain, delayed reepithelization and the complications assoicated with
long term use of topical steroid.
Key words : excimer laser, photorefractive keratectomy (PRK), laser assisted in
situ keratomi leusis (LASIK), microkeratome, spherical equivalent refraction
(SE), best corrected visual acuity (BCVA), uncorrected visual acuity (UCVA)