Transcript Introduction(continued)

Prevention of corneal
haze following PRK
using extended wear
contact lens
Khakshoor Hamid
Eslampoor Alireza
Saffarian Ladan
The authors have no financial interest in the subject matter
of this e-poster.
Page 1
Introduction
• Excimer laser photorefractive keratectomy (PRK)
with adjunctive mitomycin C (MMC; MMC–PRK)
has recently been used as an alternative to laser
in situ keratomileusis (LASIK) for surgical
correction of refractive errors.
• Corneal haze is a major disadvantage of PRK.
• It is characterized by subepithelial fibrosis caused
by abnormal wound healing.
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Introduction(continued)
• Mitomycin C is an alkylating agent that
inhibits DNA and RNA replication and protein
synthesis.
• It regulates fibroblast proliferation and
differentiation, and subsequently blocks
myofibroblast formation, which is responsible
for corneal haze after PRK.
• Some concern exists for MMC long-term
toxicity to keratocytes, endothelial cells, and
intraocular structures.
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Introduction(continued)
• Confocal microscopy has been employed by
several investigators to monitor changes in
keratocyte density during contact lens wear
and showed keratocyte loss.
• These studies suggested that contact lens
induced keratocyte loss could be attributed to
hypoxic, cytokine-mediated, and mechanically
induced effects.
• Stapelon et al. showed that extened-wear
contact lens inhibit PMN recruitment.
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Purpose
To evaluate the efficacy and
safety of using extended
wear contact lens in inhibiting
haze formation after excimer
laser photorefractive
keratectomy (PRK).
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METHODS
•A prospective, comparative
interventional case series was
conducted of 20 eyes (10 patients) with
moderate myopia of 4 to 7 diopters.
•There were 1 man and 9 women with
mean age of 27.7 years old.
•All eyes were evaluated preoperatively
using complete ocular examination,
corneal imaging by Orbscan and
specular microscopy.
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METHODS(Continued)
•Completely normal patients with pure myopia
or myopic astigmatism with spherical
equivalent of 4 to7 diopters were treated with
PRK.
•For prevention of haze formation following
PRK randomizely one eye of any patient was
treated with MMC (0.02%) using a soaked
cellulose sponge placed over the ablated
area for about 35 seconds and an extended
wear soft contact lens was applied to other
eye for one month without using
intraoperative MMC.
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METHODS(Continued)
•All patients were followed for 3-7 months
with mean follow-up time of 4.9 months.
•Refraction, uncorrected visual acuity
(UCVA), best spectacle-corrected visual
acuity (BSCVA), slit-lamp evidence of
corneal opacity (haze) and specular
microscopy were evaluated at 1 month, 3
months and last examination.
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Results
•Corneal haze was not seen in none of eyes in
both groups.
•Postoperatively the spherical equivalent
decreased from -5.25 +/- 1.25 to -0.25 +/- 0.5
diopters (D) in MMC group and from -5.00 +/0.75 to -0.30 +/- 0.50 in contact lens group (P
< 0.001).
•All eyes achieved uncorrected visual acuity of
20/20, 3 months postoperatively.
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Results(Continued)
•There was no significant difference between
last uncorrected visual acuities and
remained refractive error in both groups.
•The difference between pre and post
operatively endothelial cell count was not
significant.
•Bacterial keratitis and other complications of
bandage contact lens were not found in any
eyes.
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Conclusion
•Using extended wear bandage
contact lens is an efficacious and
safe method for inhibiting corneal
haze following PRK.
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References
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