Deep anterior lamellar keratoplasty in post-laser in situ

TECHNIQUE
Deep anterior lamellar keratoplasty in post-laser
in situ keratomileusis keratectasia
Alberto Villarrubia, MD, Juan J. Pérez-Santonja, MD, PhD, Elisa Palacı́n, MD,
Paz Rodrı́guez-Ausı́n P, MD, Antonio Hidalgo, MD
We describe a technique using deep anterior lamellar keratoplasty (DALK) in 5 eyes that developed
keratectasia after LASIK. The technique is based on surgical manipulation that allows visualization
of the lamellar dissection depth using a posterior approach to reach the predescemetic space. The
mirror effect, indentation effect, and folding effect were used to determine proximity to Descemet’s membrane. The same diameter donor and recipient buttons were used to correct myopia.
The donor button without Descemet’s membrane was placed using 10-0 nylon sutures. No intraoperative or postoperative complications occurred. The mean best spectacle-corrected visual acuity changed from 0.16 diopter (D) G 0.05 (SD) (range 0.10 to 0.25 D) before DALK to 0.68 G 0.19 D
(range 0.5 to 1.0 D) after DALK. Deep anterior lamellar keratoplasty may be a better alternative than
penetrating keratoplasty for any pathology with healthy endothelium.
J Cataract Refract Surg 2007; 33:773–778 Q 2007 ASCRS and ESCRS
Ectatic corneal disorder (ECD) is commonly used to
refer to any condition that leads to progressive corneal
thinning and an increase in corneal curvature, with
multiple sequelae that lead to loss of best spectaclecorrected visual acuity (BSCVA).1 Corneal disorders
such as keratoconus, pellucid marginal degeneration,
keratoglobus, and corneal ectasia after laser in situ keratomileusis (LASIK) fit this definition of ECD. Representing a major health burden, ECDs are the second
most common indication for penetrating keratoplasty
(PKP) in the United States.1
Subtractive corneal procedures such as excimer laser surgery induce weakening of the cornea postoperatively that can lead to corneal ectasia (keratectasia).1,2
A reduction in the tensile strength of the cornea is considered a major risk factor for the development of keratectasia. Iatrogenic keratectasia can occur months or
years after LASIK and leads to irregular astigmatism
and visual distortion.1
Currently, the definitive treatment for iatrogenic
keratectasia is PKP. However, there are only a few reports of successful PKP in the treatment of iatrogenic
keractectasia.2–7 One significant disadvantage of PKP
is the potential for graft rejection, which can lead to
significant loss of BSCVA. An alternate approach to
the treatment of post-LASIK keratectasia is deep anterior lamellar keratoplasty (DALK), a partial-thickness graft that preserves the host endothelium and
Descemet’s membrane (DM). Deep anterior lamellar
keratoplasty has been reported for the treatment of
keratoconus,8 but to our knowledge, there are no reports of DALK for the treatment of post-LASIK keratectasia. We report our technique and outcomes
using DALK in 5 eyes that developed keratectasia after
LASIK.
Accepted for publication December 15, 2006.
SURGICAL TECHNIQUE
Surgery was performed by 2 of us (A.V., patients 1, 2,
and 3; J.J.P.-S., patient 4). The criterion for surgical intervention with DALK was reduced BSCVA with
spectacles or contact lenses. Deep anterior lamellar
keratoplasty was performed using the Melles et al.9
technique. Briefly, the technique is based on surgical
manipulation that allows visualization of lamellar dissection depth using a posterior approach to reach the
predescemetic space.10 After air is delivered into the
anterior chamber, the mirror effect, indentation effect,
From the Instituto de Oftalmologı́a La Arruzafa (Villarrubia, Palacı́n,
Hidalgo), Córdoba, VISSUM, Instituto Oftalmológico de Alicante
(Pérez-Santonja), Alicante, and the Hospital General Universitario
Gregorio Marañón (Rodrı́guez-Ausı́n P), Madrid, Spain.
No author has a financial or proprietary interest in any material or
method mentioned.
Corresponding author: Alberto Villarrubia Cuadrado, MD, Instituto
de Oftalmologı́a La Arruzafa, Avenida/Arruzafa, n 9, 14012,
Córdoba. Spain. E-mail: [email protected].
Q 2007 ASCRS and ESCRS
Published by Elsevier Inc.
0886-3350/07/$dsee front matter
doi:10.1016/j.jcrs.2006.12.035
773
774
TECHNIQUE: DALK IN POST-LASIK KERATECTASIA
Table 1. Patient data before and after deep anterior lamellar keratoplasty.
Pre-LASIK
Pt/Eye
Sex
Age (Y)
Eye
Spherical Equivalent (D)
1/A
2/B
3/C
4/D
5/E
M
M
M
F
F
32
28
40
31
31
OD
OS
OS (ectasia both eyes)
OD
OS
8.00
6.00
5.00
12.75
14.25
Central Pachymetry (mm)
Topographic Pattern
BSCVA
523
Unknown
Unknown
531
554
Unknown
Unknown
Unknown
FFK
FFK
0.6
1.0
0.8
0.6
0.6
BSCVA Z best spectacle-corrected visual acuity; DALK Z deep anterior lamellar keratoplasty; FFK Z forme fruste keratoconus
and folding effect are used to determine the proximity
of the knife to DM.10 At the predescemetic space, spatulas (2110, DORC International BV) were used to dissect this space up to the limbus, followed by delivery
of an ophthalmic viscosurgical device (OVD). On
maintenance of this pseudo anterior chamber, trephination was performed until the OVD emerged. Finally,
scissors were used to remove residual stroma from the
recipient bed and the donor button without DM was
placed using 10-0 nylon sutures.9
Postoperatively, the patients were initially instructed
to instill topical fluorometholone 4 times a day,
with a tapered schedule over 4 months. Sutures were
removed 4 months after surgery if needed.
Results
Four patients (5 eyes) had DALK between 2002 and
2005 for the treatment of post-LASIK keratectasia. The
mean age of the 3 men and 1 woman at the time of
DALK was 32.4 years between G 4.51 (SD) (range 28
to 40 years). Three eyes of 3 patients (1, 2, and 3) and
both eyes of 1 patient (4) had DALK (Table 1). Before
LASIK, patient 1 had a spherical refractive error; patients 2 and 3 denied the existence of astigmatism.
The pre-LASIK corneal topography of eyes A, B, and
C were not available as LASIK had been performed
at another institution. Patient 4 had forme fruste keratoconus (FFK) in both eyes before LASIK (Table 1). Eye
E was retreated for a residual refractive error 6 months
after primary LASIK. Patients 1 and 2 developed unilateral keratectasia after LASIK; patients 3 and 4 developed bilateral keratectasia (Table 1). Patient 3 had
DALK in the left eye due to reduced BSCVA; the right
eye has retained excellent BSCVA and has not had
DALK.
The mean time from LASIK to the clinical diagnosis
of keratectasia was 19.2 G 17.60 months (range 6
months to 4 years) and from the diagnosis to the
performance of DALK, 3.3 G 1.3 years (range 2.0 to
5.5 years). The time to DALK differed because keratectasia progressed at different rates, which reduced the
BSCVA at different time points. As all eyes presented
with an axial length longer than 24.0 mm, the same diameter was used for the donor button and the recipient
bed to correct some myopia.
The mean manifest refractive spherical equivalent
(MRSE) was 9.20 G 4.11 D (range 5.00 to 14.25 D)
before LASIK, 12.85 G 6.22 D (range 7.00 to 21 D)
before DALK, and 7.1 G 5.67 D (range 1.50 to
13.50 D) after DALK. The mean BSCVA was 0.72 G
0.20 (range 0.6 to 1.0) before LASIK, 0.16 G 0.05 (range
0.1 to 0.25) before DALK, and 0.68 G 0.19 (range 0.5
to 1.0) after DALK. Eyes C and E experienced a
1-line loss of BSCVA after DALK (Table 1); however,
only 6 months of follow-up were available for eye C
(Table 1). No intraoperative or postoperative complications occurred.
Case Reports
Eye A The corneal topography before DALK showed
curvature changes consistent with ectasia (Figure 1,
A); after DALK, it showed a more regular astigmatism
pattern, with significantly reduced steepening (Figure 1, B). Slitlamp examination of the cornea 12
months after DALK showed folds in DM inferiorly,
sparing the pupil (Figure 1, C). Histology of the recipient cornea showed integrity of Bowman’s lamina,
a thick flap, and the absence of DM and endothelium
(Figure 1, D).
Eye E The keratometric corneal topography before
LASIK showed a pattern consistent with FFK (Figure 2,
A). Keratometric corneal topography after LASIK and
before DALK showed a pattern consistent with inferior ectasiadsteep curvature changes inferiorly (Figure 2, B). The keratometric corneal topography after
DALK showed a reduction in corneal curvature
changes (Figure 2, C). Twelve months after DALK,
the interface was not visible (Figure 2, D).
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TECHNIQUE: DALK IN POST-LASIK KERATECTASIA
Pre-DALK
Time from LASIK
to Ectasia
Diagnosis (Mo)
Time from Ectasia
Diagnosis
to DALK (Y)
6
24
48
9
9
3
3
5.5
3
2
Post-DALK
BSCVA
Refractive
Error (D)
Size
Recipient
Donor (mm)
Examination (Mo)
BSCVA
0.15
0.25
0.1
0.15
0.15
6.0 6.0 130
5.0 4.0 65
7.5 3.5 130
18.0
20.0 2.0 10
8.5–8.5
8.0–8.0
8.5–8.5
8.0–8.0
8.0–8.0
12
12
6
24
18
0.6
1.0
0.7
0.6
0.5
Refractive
Error (D)
4.5
4.0
0.5
11.5
11.0
3.0 170
4.0 175
2.0 130
2.0 40
5.0 180
Figure 1. Eye A (first patient). A: Orbscan corneal topography before DALK showing central and inferior ectasia. B: Orbscan corneal topography
after DALK. C: The cornea 12 months after DALK showing folds in the intrapupillary part of DM. D: Histology of the recipient cornea showing
integrity of Bowman’s lamina, thick flap, and absence of DM and endothelium.
DISCUSSION
Keratectasia after LASIK is a progressive condition
that eventually leads to loss of BSCVA and reduction
in visual quality.1 The first case of post-LASIK
keratectasia was described in 1998.2 However, accurate estimates of the number of eyes that develop ectasia after LASIK are not available due to the lack of
reliable data (Cornea Clinical Committee, ‘‘Corneal
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TECHNIQUE: DALK IN POST-LASIK KERATECTASIA
Figure 2. Eye E (fourth patient). A: Corneal topography before LASIK showing a pattern similar to that of FFK. B: Corneal topography before
DALK showing a pattern consistent with inferior ectasia. C: Corneal topography after DALK. D: Twelve months after DALK, the interface is not
visible.
Ectasia After LASIK,’’ presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, San
Francisco, California, USA, April 2003). The onset of
ectasia after LASIK varies between 3 months and 5
years.11,12 In our series of 4 patients, the earliest diagnosis of ectasia was 6 months after primary LASIK
and the latest was 4 years. Keratectasia has been reported to occur more frequently after retreatments,13
as seen in the left eye of patient 4 in our study.
The disruption of corneal integrity by a combination
of the flap cut and excess tissue removal leaving less
than 250 mm of residual stromal bed depth is considered a significant precipitating factor for the development of ectasia.13 The lack of consistency in flap
thickness and stromal dehydration can lead to variable
residual stromal bed depth postoperatively. Collagen
fibers in corneal stroma are organized from limbus to
limbus perpendicularly. The tensile strength of the organized stromal tissue is reduced by the creation of the
flap during LASIK. Coupled with tissue removal, this
could trigger corneal irregularity due to intraocular
pressure (IOP).
A significant risk factor for the development of keratectasia is preoperative FFK. Histologic studies of explanted ectatic corneas that had LASIK show
structural alterations in Bowman’s lamina that are
highly indicative of keratoconus.2–6 From these studies, it is clear that LASIK was performed in a cornea
with preexisting FFK. However, there are other reports in which Bowman’s lamina had no structural
changes consistent with keratoconus,4–7 similar to
the case that we present (Figure 1, D). It is likely that
in this case, keratectasia developed due to a thicker
flap than intended and/or a predisposing factor that
is currently unknown. We are not able to determine
whether eyes A, B, and C presented with FFK prior
to LASIK because these patients were referred from
elsewhere and pre-LASIK corneal topography was
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TECHNIQUE: DALK IN POST-LASIK KERATECTASIA
not available. Corneal topography of eyes D and E
(both eyes of the same patient) do show FFK before
LASIK (Figure 2, A).
A wide range of therapies are available for keratectasia, from rigid gas-permeable (RGP) contact lenses
to surgical intervention such as PKP.14 Therapy is
usually initiated based on the severity of the condition. We recommend an initial trial with ocular hypotensive agents (eg, timolol) as complete reversal of
keratectasia has been described with this treatment.15
If this trial is not successful, we opt for optical correction with spectacles or RGP contact lenses. If optical
correction does not yield optimal visual acuity, surgical treatment is warranted. The recent introduction
of corneal collagen crosslinking may be a less invasive, temporary therapy for the progression of
keratoconus.16
Intrastromal corneal ring segments (Intacs, Addition Technology; Ferrara, Visiontech Medical Optics)
represent a surgical alternative. Intacs can correct myopic regression after LASIK as well as keratectasia after LASIK.17–21 Our experience is that Intacs are
a successful treatment for central ectasia rather than inferior ectasia. In cases of inferior keratectasia, greater
success has been achieved by implanting 1 inferior Intacs segment instead of 2.22 If ectasia is central, 2 Intacs
segments are required.22
If Intacs are not successful, corneal transplantation
(penetrating or lamellar) is the next logical option.
Successful results have been reported with PKP.2–7
However, to our knowledge, there are no reports
of DALK for the treatment of post-LASIK ectasia.
There are reports of DALK for the treatment of keratoconus.8 The advantages of DALK over PKP for
any corneal pathology with healthy endothelium
have been described.23 Advantages of DALK over
PKP include faster functional outcomes because sutures can be removed sooner than in PKP; there is
no risk for endothelial rejection, and the survival
of the transplant is longer since endothelial density
declines slowly over a period of years after PKP.
The main disadvantage is that DALK is a technically
demanding and time-consuming procedure. Additionally, poor quality of vision may be likely due
to the light scatter between the 2 interfaces. Although we agree that poor quality of vision is a possibility, in our opinion, the benefit of faster visual
rehabilitation and easier postoperative management
are reasons to select DALK over PKP. This is especially true in patients with keratoconus and with
post-LASIK ectasia, who are generally young and
socially active. The BSCVA after DALK is similar
to that obtained after PKP for the treatment of keratoconus.8 If exposure of DM has been performed
777
without intraoperative complications, the BSCVA
outcomes should be similar for DALK and PKP,
which is what we found in this series of 5 eyes.
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J CATARACT REFRACT SURG - VOL 33, MAY 2007
First author:
Alberto Villarrubia, MD