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Intra-operative complications are surgical complications
that occur during the procedure itself.
Microkeratome-Related
Complications
Patients should understand that the incidence of such
complications is generally low. If one occurs, most
surgeons will not proceed with the laser ablation at
that time. Irregular cuts rarely lead to significant
visual loss, and most of the time the surgeon will simply
end the procedure that day and re-schedule the surgery
a few months later.The incidence of all microkeratome-related
complications reported in the literature range from
0.7% to 11.8%, but studies with the largest sample sizes
demonstrate complication rates of 2.2% or less.1
| Study |
Complication
Rate |
| CRS-USA LASIK Study (n=1800)2 |
1.2% |
| Emory Study (n=1,062)3 |
1.8% |
| Lin & Maloney (n=1,019)4 |
2.2% |
| Tham & Maloney(n=3998)5 |
0.7% |
As of April 1, 1998, the CRS-USA LASIK Study that considered
1,800 eyes noted two complications that arose during
the procedures themselves resulting from the microkeratome:
irregular cuts damaging the stromal bed (experienced
by 0.03% of the patient population) and damage to the
epithelium (0.47%). Two types of complications required
patients to forgo treatment or return another day but
did not cause loss of visual acuity: flaps were too
small (0.38%) or too thin (0.38%). All of the aforementioned
complications produced temporary effects. After 3 months,
the visual results of the group experiencing Intra-operative
complications were no different from the group who experienced
no such complications.2
In January, 1999, the Emory group published a study
on the results 1530 surgical procedures on 1062 eyes,
and noted a 1.8% intra-operative complication rate.
Seventeen eyes had to forgo treatment that day due to
flap complications. Only 3 eyes (0.28%) lost 2 or more
Snellen lines of best complications. Only 3 eyes (0.28%)
lost 2 or more Snellen lines of best corrected visual
acuity (BCVA).3 It
should be noted that this study was based on procedures
done well before the study's publication in 1999 and
that the procedures used microkeratome and laser technology
that has since been improved.
A 1999 study conducted by Doctors Robert Lin and Robert
K. Maloney that considered 1,019 eyes for which a flap
was created by means of a microkeratome noted a 2.2%
intra-operative complication rate. However, no eyes
suffered permanent decrease in visual acuity because
of flap complications.4
A study of 3998 eyes noted a 0.68% flap complication
rate - 27 eyes. Five had buttonholes (small tears or
cuts), 2 had free caps (incisions that resulted in "flap"
being cut off), 4 had irregular flaps, 7 had incomplete
flaps, 9 had thin flaps and 5 had small flaps. Five
eyes had more than one complication. Upon laying down
the flap, twenty-six of the eyes recovered to within
one line of best corrected visual acuity, and one eye
lost two lines. Sixteen eyes had repeat LASIK, and all
eyes that were retreated recovered to within one line
of pre-operative best corrected visual acuity.5
Excimer
Laser Ablation-Related Complications
Decentered ablations and central islands were considered
in reports that appeared in 1999 or earlier. Incidence
ranges from 1.2% for myopia (2 of 396 eyes)6
to 6.8% for early hyperopic astigmatic treatment (4
of 58 eyes).7 Eyes
with decentered ablations and central islands generally
required the use of rigid contact lenses for best vision
correction.
As excimer laser technology and the surgical technique
have been refined and advanced, these two complications
are rarely seen today. Of the clinical studies submitted
to the US FDA for approval of excimer laser systems,
none reported decentered ablations or central islands.8
Recent advances in laser technology, called wavefront
custom ablations, hold the promise of treating these
conditions and alleviating the visual problems associated
with them. For more information on custom ablations,
please see our Technology
section.
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