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学会・論文発表 |
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 A.D.
Semyonov, A.V.Doga, G.F.Kachalina,
K.Okuyama, I.A.Alisov, N.A.Semyonova
Specific Features of Clinical Course in Photoastigmatic Refractive
Keratectomy with the "Profil-500"at Different Terms Postoperatively
The work analyzes the clinical course of PARK performed using
the "Profil-500" in 250 eyes with compound myopic astigmatism
to 5.0D with myopia to 10.0D. Operation was done through transepithelial
access. ln all cases complete epithelialization of the cornea
was recorded within 24−48h. By 6−12 months postoperatively and
until 3years of follow−up the cornea of eyes operated on was
comPletely transparent in 91.2％ of cases; opacities of 0.5−1
degree Were found in 8.8％ of cases which did not affect final
refractive result.
Numerous studies investigating the condition of the cornea
at different terms after photorefractive keratectomy(PRK) and
photoastigmatic refractive Keratectomy(PARK) indicate tnat tne
corneal syndrome is the typical feature of clinical course in
the early postoperative period of these excimerlaser interventions
in myopia and myopic astigmatism. The degree of syn drome indetermined
by the type and area of erosion surface，time and period of cornea
epithelialization，and condition of corneal epithelium anu stroma
by the moment of completing epithelialization. Many authors
consider the above facts to play an important role in the further
development of subepithelial fibroplasia which forms corneal
opacities of different degrree leading to unpredictable regression
of postoperative refractive result[1,3,6,9,12,13]
Notably, from literature, the techniques of PRK and PARK with
different foreign excimer laser devices are performed with preliminary
scarification of the corneal epithelium [4,5,7,8]. Thus, it's
necessary to stress that the device "Profil-500" elaborated
at the Center of Laser Surgery of the Eye Microsurgery Complex,
like all previous Profil models of several generations ,allows
transepithelial correction of myopia and myopic astigmatism
i.e., without preliminary scarification of epithelium.
The objective of the work is to study clinical course of the
postoperative period after transepithelial PARK with "Profil-500"
on the basis of postoperative results.
Material and methods
PARK was performed in 250 eye sof 131 patients aged 18 to 45
years with compound myopic astigmatism to 5.OD with myopia to
1O.OD. The follow−up was 3 years.
In all cases the operation was performed by transepithelial
method, i.e., with subsequent evaporation of epithelium, Bowman's
membrane and superficial layers of the corneal stroma. The operation
lasted not more than 1.5 min. No intraoperative complications
were recorded．
Biomicroscopy of the anterior sector in eyes operated on was
performed using slit-lamp("opton”,Germany). To evaluate tne
pattern and duration of corneal epithelialization and find defects
in it, we used fluorescein probe according to routine method
with the
use of 1% fluorescein solution.
We evaluated in the postoperative period(a) the degree of corneal
syndrome and subepithelial fibroplasia according to the classification
developed at the Eye microsurgery Complex(Kornilovsky I.M.,1995)
[2]; (b) degree of corneal opacities according to the world
numeric classification accepted in excimer laser practice.
Results and discussion
In most eyes operated on (184eyes-73.6%)，irrespective of the
degree of initial astigmatism and sphere equivalent(SE)，We found
epithelial form of corneal syndrome manifested by minimal involvement
of corneal stromal layers adjacent to ablation zone. In these
cases ablation zone was completely covered with epithelium within
24−36h postoperatively; edema of superficial corneal stromal
layeres adjacent to intervention zone was rather mild or almost
absent. Photophobia and lacrimation disappeared 1-2 days postoperatively
as a rule. In 66 eyes(26.4%) stromal type of the corneal syndrome
was recorded which was accompanied by moderate edema of all
stromal layers in ablation zone. Notablv, in these eves the
initial SE varied from 8.25 to 15.0 D, being more than 10.0
D on average. This required the removal of great volume of tissue
and, thus, the use of greater energy and pulse number for photochemical
evaporation of the cornea. Complete epithelialization in these
eyes was recorded 36-48 h postoperatively; stromal edema gradually
decreased with epithelialization and almost disappeared by day
5-7 postoperatively. Notably, we found no cases of mixed type
of the corneal syndrome consisting in longer epithelialization
to 72 and more hours postoperatively and pronounced stromal
edema of entire ablation zone with signs of descemetitis. This
was confirmed by fluorescein probe allowing detailed evaluation
of corneal epithelialization and exclusion of uneven and chaotic
epithelialization with poorly fixed and mobile epithelium. Thus,
uncomplicated postoperative course after transepithelial PARK
was recorded in almost all cases By day 5-7 postoperatively
the anterior eye sector was calm, the cornea was smooth, bright
and transparent. Only in some cases biomicroscopy revealed slightly
thickened epithelial layer of the cornea with mild subep ithelial
opalescence; its intensification accompanied by appearance of
whitish inclusions in the cornea are considered to be the first
signs of development of subep ithelial fibroplasia [2]. We analyzed
clinical course of transepithelial PARK at different terms of
postoperative period and recorded no visible signs of fibroplasia(degree
0) in 136(54.4%) eyes from the first days after surgery and
during the whole follow-up to 3 years. As a rule, SE in these
cases did not exceed 8.5 D. In 92(36.8%)eyes 8-14 days postpperatively
and irrespective of the value of initial refraction, reversible
form of subepithelial fibroplasia was recorded. Its symptoms
intensified during 1-3 months postoperatively and gradually
disappeared by 6-12 months postoperatvely. From our viewpoint,
timely and correct topical corticosteroid and resolving therapy
affected the rate of fibroplasia regression that in agreement
with data of other authors[10, 11] Partially reversible type
of fibroplasia was recorded in 22(8.8%) eyes. Average SE was
higher tnan 10.0 D ln these eyes. Due to medication (corticosteroid
and resolving therapy) only delicate and spotty opacities of
0.5-1 degree remained at tne periphery and in tne center of
ablation zone by 6-l2 months after PARK which almost did not
affect postoperative visual acuity and did not cause its decrease
as compared to that with glasses preoperatively.
We found irreversible subepithelial fibroplasia with signs of
pronounced fibrosis in the corneal stroma and accompanied by
significant decrease of refractive effect in none of the cases.
This data correlate with results of clinical observations at
the Center of Laser Surgery of Eye Microsurgery Complex analyzing
40,000 PRK and indicating that this type of fibroplasia is rather
rare and its occurrence is not more than 1.4% of cases. The
degree of manifestation of postoperative corneal opacities in
ablation zone is presented in Table.
Thus, 6-12 months after PARK and during the further follow-up
until 3 years corneal opacities caused by subePithelial fibroplasia
were recorded in only 8.8% of cases. Transepithelial access
in PARK technique using "Profil-500" allows significant degrease
of degree and duration of corneal syndrome and decreases 1.5-2
times the period of complete epithelialization of the cornea
that, in turn, sharply reduces the degree of subepithelial fibroplasia
in postoperative period and significantly increases the percentage
of high and stable refractive results.
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