Late-Onset Dehiscence of LASIK Flap

1
Late-Onset Dehiscence of LASIK Flap

• Poster Number P-190
• Authors Hyunjin Jane Kim, Cary M. Silverman
• Category Keratorefractive
• Authors have no financial interest or disclosures

2
Introduction Corneal flap displacement within 1
to 2 days following laser in situ keratomileusis
(LASIK) is a well recognized complication.1-3
However, stability of the flap remains largely
unknown as flap dehiscence has been reported as
late as 7 years after LASIK.4 We report cases of
flap dislocation 4 years and 9 years after laser
LASIK, following trauma during routine domestic
activities. We also review 33 known case reports
of late flap dehiscence, most of which are single
case reports. Largest case series described 4
patients with flap dislocadtion.5
3
Case 1 A 30-year-old Black man had a LASIK
procedure on July 8, 2004. Patient had an
uncomplicated post operative course with
uncorrected visual acuity (UCVA) of 20/20 in both
eyes, and best spectacle corrected vision (BSCVA)
was 20/15 with refractive error of -0.25-1.00 x
165 and plano -0.75 x 170, respectively. On June
23, 2008, 4 years post LASIK, patients right eye
was struck with a piece of wood from a window
trim. He presented two days after complaining of
pain and slight decrease in vision in the right
eye. Exam showed UCVA of 20/25 with a mild
displacement of flap creating a fold and staining
at the superior edge (Figure 1A). Because the
injury involved the periphery of the flap and
vision was good, patient was treated medically
with Vigamox (Alcon, Fort Worth,Texas) and
Lotemax (BauschLomb, Tampa, Florida) four times
daily. Three days later, pain resolved and the
UCVA was 20/30. By biomicroscopy, patient had
persistent folds but the staining had improved.
Drops were discontinued a week later. Five weeks
after trauma, UCVA was 20/20-1 with no staining
on slit lamp. Folds persisted as seen on Figure
1B.
4
Figure 1A. Color photos of right eye 2 days after
being struck by a piece of wood from a window
trim. Note a mild displacement of flap creating
folds and staining at 12 oclock position.
Figure 1B. Color photo of right eye after medical
treatment of peripheral flap dehiscence. Flap
folds persist just superior to the visual axis.
5
Case 2 A 29 year-old man underwent bilateral
LASIK on February 1, 1999. Two years
postoperatively, UCVA was 20/30 and 20/40 and the
BSCVA was 20/25 (plano -0.50 x 175) in the right
eye and 20/20 (-0.50 -0.75 x165) in the left eye.
On March 18, 2008, after 9 years and 1.5 months
since the uncomplicated LASIK, the patient
presented to emergency room 3 days after getting
struck with a dogs paw in his left eye. Patient
experienced a sharp pain and sudden decrease in
vision. Patient was discharged from the
emergency room on antibiotic drops as treatment
for corneal abrasion, and was seen by an
optometrist the next day, who then referred the
patient to the author (CMS). Upon first visit to
our service, 5 days after initial trauma, the
UCVA was count fingers and the slit lamp exam
showed complete flap dislocation with mild flap
edema without tears (Figure 2A). Stromal bed of
the flap was epithelialized and interface did not
have debris. Immediate removal of epithelium from
stromal bed was completed under laser microscope.
The flap interface was irrigated with balanced
salt solution and the flap was repositioned using
irrigating cannula, Weck-Cel sponges and a patent
spatula. No alcohol glue or sutures were used.
The field was then irrigated with vancomycin
fortified solution. A bandage contact lens
secured the flap (Figure 2B) and patient was
maintained on Vigamox and Omnipred (Alcon, Fort
Worth,Texas), both at four times daily for 10
days. Patient was seen in follow up in 1 day, 1
week, and 1 month, and 3, months. Final UCVA was
20/25, with no evidence of epithelial ingrowth,
folds or diffuse lamellar keratitis
.
6
Figure 2A. Color photo of left eye 3 days after
being struck by dogs paw. Flap is totally
dislocated toward the nasal canthus, attached at
the nasal hinge without a tear. Whitish debris
represents epithelial ingrowth that is
encompassing about 30 of stromal bed involving
the visual axis.
Figure 2B. Color photo of left eye with bandage
contact lens after surgical repair of the flap
dislocation and epithelial ingrowth. There was no
residual epithelial ingrowth and cornea was clear
(note photographic artifact on inferonasal
cornea).
7
Discussion Absence of scar formation in the
lamellar interface explains rapid restoration and
persistence of post-LASIK visual acuity.6, 7
Consequently, early displacement of LASIK is a
well known phenomenon documented in large
studies. Gimbel and associates reported 12 eyes
of 1000 (1.2) that had slipped flap within a day
postoperatively.1 Similarly, Lin and Maloney
reported 20 eyes out of 1019 (2.0) that had
displaced flap within 24 hours of LASIK.2
Stulting and associates repositioned 13 eyes out
of 1062 (1.2) within 2 days of surgery for
dislocated flaps.3 Smaller case reports and
series have been published on late (postoperative
week one or more) presentation of flap
dislocation. Our case is the first report in the
English literature of flap displacement after
over 9 years following LASIK, and a second report
of late flap dehiscence treated medically without
surgical repair. 33 cases have been reported on
late onset unilateral flap displacement.4-26 Mean
age was 35 years and there were 19 men and 15
women. Mechanisms of flap displacement ranged
from spontaneous8, iatrogenic9, to traumatic
displacement due to domestic tools4, 10-13,
finger injury4, 5, 14, 15, airbag12, 16, 17,
ball5, 18, 19, and animals5, 20, 21. The onset of
flap slippage ranged from 10 days to 7 years.
Most common presentation was immediate visual
loss associated with pain. Slit lamp
biomicroscopy revealed partial dehiscence of the
flap in all but one case in which there was a
total loss of flap.15 Sixteen cases (48)
presented with flap folds, and 10 cases had
epithelial ingrowth, which was associated with
delayed presentation after injury.
8
Discussion Continued Only 2 cases of epithelial
ingrowth were seen within 24 hours of injury
and the rest presented 2 to 26 days after the
injury. Twenty-two cases (67) achieved final
uncorrected or best spectacle corrected visual
acuity of 20/20. Seven eyes (21) went down in
vision with the worst visual loss of 3 lines
corresponding to the total loss of LASIK flap.15
All but 4 eyes underwent surgical repair at the
first presentation following trauma. Two of the 4
cases underwent surgery later21, 22, one case was
treated medically only22, and the last case had
total flap loss.15 After initial treatment, 11
eyes developed diffuse lamellar keratitis, and 14
eyes epithelial ingrowth. Eleven of the 14 cases
required additional surgery to remove epithelium
ingrowth. Lack of stability of the flap can be
attributed to the same reasons that give rise to
the optical clarity of flap. Animals as well as
human studies have shown that adhesion between
the flap-stromal bed interface is limited to the
edge of the wound.6-7 We postulate that if enough
force is applied tangential to the flap
undermining tissue adhesions at the edge of the
flap, the rest of the flap is then at risk of
partial or total dislocation. This phenomenon is
observed when the author (CMS) lifts the flaps
more than 10 years following the original LASIK
to perform enhancement surgeries.
9
Discussion continuedWe herein report the
latest presentation of traumatic flap
dislocation, emphasizing the fact that flap
interface is vulnerable to traumatic dehiscence
for up to 9 years following LASIK. The cases
reported are comparable to 33 cases in
literature. Case 2 presented 3 days after being
struck with dogs paw, and had extensive
epithelial ingrowth. Despite delayed presentation
and the extent of the injury, he was successfully
treated and enjoyed good visual outcome. On rare
occasions, peripheral flap dehiscence may be
treated medically without surgical intervention
as shown in Case 1 and in a case reported by
Heickell and associates.22 In both cases, patient
achieved final BSCVA of 20/20 after treatment
with topical medications.All patients
undergoing LASIK should be educated about this
possible complication associated with lamellar
corneal wound and instruct patients to seek
ophthalmologic attention immediately to avoid
other complications associated with flap
dehiscence. The surgeon may also urge patients to
use protective eye wear or even consider an
alternative refractive procedure for patients
with increased occupational hazard to blunt eye
trauma, such as those who work in the military or
law enforcement, or contact sport. Prompt
surgical invention, however, is effective in
restoring visual acuity in case of flap
displacement.
10

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