Full text of DOI:10.1007/s00417-002-0499-2

Graefe’s Arch Clin Exp Ophthalmol
(2002) 240:639–643
C L I N I C A L I N V E S T I G AT I O N
DOI 10.1007/s00417-002-0499-2
Manfred Spitznas
Jens Eckert
Martine Frising
Nicole Eter
Long-term functional and topographic results
seven years after epikeratophakia
for keratoconus
Abstract Purpose: To analyze the
long-term effect of epikeratophakia
refractive power of the cornea de-
creased from 51.8 to 45.8 and astig-
Received: 21 December 2001
Revised: 26 April 2002
Accepted: 14 May 2002
Published online: 13 July 2002
© Springer-Verlag 2002
(EKP) on corneal topography and vi- matism from 7.2 to 3.8. SAI im-
sual acuity of eyes with keratoconus. proved from 3.2 to 0.9 and SRI from
Methods: Retrospective study of 36
eyes 7.2 years after EKP. Four eyes
underwent penetrating keratoplasty
(PKP) and were excluded from fur-
3.7 to 0.9. Mean BCVA was 0.3 pre-
operatively and 0.6 upon last follow-
up. Conclusions: EKP was able to
render PKP unnecessary in 32 of 36
ther evaluation. Best-corrected visu- eyes during the entire observation
al acuity (BCVA) values were ob-
tained from 32 eyes, corneal refrac-
tion and astigmatism from 23 eyes,
surface asymmetry index (SAI) and
surface regularity index (SRI) from
17 consecutive eyes that were oper-
ated upon after 1991, when the
Tomey Topographic Modeling
System became available.
period. It was successful in perma-
nently flattening the ectatic cornea
and reducing astigmatism while re-
storing a symmetrical and smooth
corneal surface. As a result, visual
acuity improved considerably. In
view of the young age of keratoco-
nus patients needing surgery, and the
fact that the lifetime of full-thickness
M. Spitznas ( ) · J. Eckert · M. Frising
✉
N. Eter
Department of Ophthalmology,
University of Bonn Medical Center,
Sigmund-Freud-Strasse 25, 53105 Bonn,
Germany
e-mail: umc000@uni-bonn.de
Tel.: +49-228-2875647
Fax: +49-228-2875603
Results: Only four eyes needed PKP. corneal grafts is limited, EKP should
In addition to EKP six eyes had
compression sutures and/or relaxing
incisions, and one eye underwent
photorefractive keratectomy. Mean
be considered a valuable alternative
to PKP in contact-lens-intolerant
cases of keratoconus without central
scarring.
Introduction
Materials and methods
Between 1987 and 1994 we performed EKP according to the tech-
nique described by McDonald and coworkers [4] on 38 eyes of
30 patients with different stages of keratoconus, causing various
degrees of bulging, thinning and posterior wrinkling, but no cen-
tral scarring. The study includes the eyes of eight patients who un-
derwent surgery on two eyes. This fact may induce some bias,
since observations on the two eyes of one person cannot be con-
sidered statistically independent. All eyes were contact-lens intol-
erant. The EKP tissue used was commercially prepared (Allergan
Medical Optics, Irvine, Calif.).
The average age of the patients at the time of surgery was 31
(±9.9) years. Observation period was 7.2 (±1.8) years. During this
period two patients died, reducing the number of eyes in this study
to 36. In 13 eyes of patients who lived far away from the clinic we
obtained the best-corrected visual acuity (BCVA) at the end of the
Epikeratophakia, a form of onlay lamellar keratoplasty,
for the treatment of keratoconus was first introduced by
Kaufmann and Werblin in 1982 [2]. The technique em-
ploys non-refractive, acellular, freeze-dried stromal len-
ticules prepared from donor corneas. After removing the
corneal epithelium of the recipient, the lenticules are su-
tured under tension to a peripheral trephine groove in the
patient's cornea with the aim of flattening the ectatic cor-
nea and postponing or avoiding penetrating keratoplasty
(PKP).We report on the functional and topographic re-
sults of this technique in the long term, 7 years after op-
eration.

640
Table 1 Number of patients receiving epikeratophakia (EKP). RI
Relaxing incisions, CS compression sutures, PRK photorefractive
keratectomy, PKP penetrating keratoplasty
Procedure
No. of patients
EKP only
25
5
EKP + RI
EKP + RI + CS
EKP + PRK
EKP + PKP
1
1
4
Total
36
Fig. 2 a Mean keratometric astigmatism before and after treat-
ment. b Individual keratometric astigmatism before and after treat-
ment
date. These topographic measurements were taken with the Tomey
Topographic Modeling System (TMS 1). Findings were compared
to the values obtained preoperatively and 3 months postoperative-
ly. Statistical analysis was performed using the signed rank test
and Spearman rank correlation.
Results
Of the 36 eyes originally available for evaluation, 4
(3 checked by the local ophthalmologist and 1 by us) un-
derwent PKP 7 months to 3 years after EKP and were
excluded from further evaluation.
Of the remaining 32 eyes, 7 had further surgical inter-
ventions, namely relaxing incisions (5 eyes) at 7 to 74
months after EKP, relaxing incision + compression su-
tures (1 eye) 39 months after EKP, and PRK 19 months
after EKP (1 eye) (Table 1). No complications occurred,
and removal of the graft was not necessary in any of the
cases.
Fig. 1 a Mean refractive power of cornea before and after treatment.
b Individual refractive power of cornea before and after treatment
observation period from the local ophthalmologists. In the remain-
ing 23 eyes the late follow-up examination was carried out at our
institution. In addition to BCVA these eyes were also examined
for corneal refraction, astigmatism, and, after the technical prereq-
uisites had become available to us in July of 1991, both surface
asymmetry index (SAI) and surface regularity index (SRI) were
obtained from all 17 consecutive eyes operated upon after this
Mean refractive power of the cornea (n=18) decreased
from 51.8 dpt (±6.5) preoperatively to 45.0 dpt (±4.9) at

641
Fig. 3 a Mean surface asymmetry index (SAI) before and after
treatment. b Individual surface asymmetry index before and after
treatment
Fig. 4 a Mean surface regularity index (SRI) before and after
treatment. b Individual surface regularity index before and after
treatment
3 months postoperatively and was 45.8 dpt (±3.1) upon
late follow-up (Fig. 1). The changes were statistically 3-month results did not differ significantly compared to
significant (P<0.001).
baseline, the late follow-up values did (P<0.001).
Mean astigmatism in diopters in the 23 eyes checked
at our institution was 7.2 (±4.1) preoperatively, 6.3
(±3.4) 3 months postoperatively, and 3.8 (±2.2) upon late Discussion
follow-up (Fig. 2). Whereas the 3-month results did not
differ significantly compared to baseline, the late follow- McDonald et al. [4] reported favorable short-term results
up did (P<0.001).
after EKP for keratoconus. However, it was not clear at
Mean SAI (n=17) improved from 3.2 (±2.0) preopera- that time whether and how long the effect was going to
tively to 1.2 (±0.7) 3 months postoperatively and further last. In our material we were able to confirm that EKP
to 0.9 (±0.4) upon late follow-up (Fig. 3). The changes did in fact flatten and reinforce the ectatic cornea. This
were statistically significant (P<0.05; P<0.001).
becomes evident when comparing the preoperative re-
Mean SRI (n=17) was 3.7(±1.9) preoperatively. It im- fractive power of the cornea (51.5 dpt) with an average
proved to 1.9 (±1.5) 3 months postoperatively and fur- corneal refraction of 45.2 dpt measured 3 months post-
ther to 0.9 (±0.3) upon late follow-up (Fig. 4). The operatively. The effect was long-lasting and remained
changes were statistically significant (P<0.05; P<0.001). stable over the entire observation period.
Mean BCVA (n=32) was 0.3 (±0.2) preoperatively.
At the same time, preoperative keratometric astigma-
After 3 months it had improved to 0.4 (±0.2) and further tism improved from 7.2 to 3.8. This improvement was
to 0.6 (±0.2) upon late follow-up (Fig. 5). Whereas the not yet very pronounced 3 months postoperatively (6.3),

642
Another quantitative descriptor of the optical quality
of the corneal surface is the surface regularity index
(SRI), which is calculated from the local regularity of
the surface over the area of the cornea enclosed by an
approximate average virtual pupil of 4.5 mm. Like the
SAI, the SRI of normal corneal surfaces is relatively low,
and higher values indicate surfaces of lesser optical qual-
ity. In our patients the SRI improved from 3.7 to 0.9,
showing that the corneal surface had not only become
symmetrical, but smooth as well.
Best-corrected visual acuity, averaging 0.3 preopera-
tively and 0.6 at long term, obtained after EKP alone in
25 eyes and after additional minor surgery in 7 eyes, was
very satisfactory. These values confirm the findings of
Waller et al. [7] on ten patients 5 years after EKP.
Seven years after EKP only 11% of the eyes in our
study had needed PKP. In view of the lasting visual re-
habilitation after EKP and the fact that the life span of
transplanted corneas is limited [5], this is an excellent
result. This is especially true when considering that the
average age of the patients at the time of surgery was
only 31 years. Our positive findings are confirmed by
the recent report by Haugen et al. [1], who described
good results of EKP in mentally retarded patients with
keratoconus. However, in contrast to us, Haugen and co-
workers prefer to perform PKP in patients under the age
of 40.
In conclusion, epikeratophakia should be considered a
valuable alternative to penetrating keratoplasty in con-
tact-lens-intolerant cases of keratoconus without central
scarring. So far, long-term results on a large series of
eyes are available only for commercially prepared, lyo-
philized lenticules. Such lenticules are still commercially
available and can be purchased from Cryo-Optics (Hous-
ton, Texas, USA). Recently, Vajpayee and Sharma [6]
Fig. 5 a Mean best-corrected visual acuity (BCVA) before and af-
ter treatment. b Individual best-corrected visual acuity before and
after treatment
but the rate of change was gradual with a maximum dur- followed 11 eyes for 4 years and Krumeich et al. [3] 8
ing the first postoperative year followed by a slow de- eyes for 2 years in which the donor lenticules had been
crease (unpublished personal observation). An identical manually prepared by the surgeon from living eye-bank
observation was made by Waller et al. [7], and these tissue, employing a manual lamellar dissection technique
findings may indicate a slow progression of the conic or cutting with a specially designed instrument. If further
process.
follow-up of a larger series produces equally favorable
Normally, power distribution across a corneal surface results, such fresh lenticules might be as useful as the
is highly symmetrical. In keratoconus this is not the case. commercially available tissue.
The asymmetry can be measured and expressed as the
Acknowledgements We are grateful to Dr. R. Fimmers from the
surface asymmetry index (SAI), which is defined as the
centrally weighted sum of the differences in corneal
Institute of Medical Biometrics, Computer Science and Epidemi-
ology for his help with statistical analysis. This study was support-
ed in part by Aktion Kampf der Erblindung.
power between corresponding points on theTMS-1 mires
180° apart. Normal corneas generally have SAI values
less than 0.5, whereas the highly asymmetrical corneas
in keratoconus may reach values above 5.0. In our 17
consecutive patients operated upon after the TMS had
become available in 1991, the SAI improved from 3.2
preoperatively to 0.9 upon last follow-up, indicating that
EKP had been successful in permanently restoring the
highly asymmetrical cornea of the patients to almost nor-
mal values.

643
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