FEMTO-LASIK and BEYOND - Carl Zeiss, Inc.

14
Ophthalmology WORLD REPORT
tures of Femto-DALK and Femto-DSEK procedures and
showed results for the VisuMax-ALK done for a post-
PRK scarring. Post-op a 20/40 was obtained.
He then showed a second patient with granular dystrophy
and previous PRK with 20/60. The patient attained 20/40
unaided on postop day 1. In the view of Dr Tan, stromal bed
quality, rim cut quality and accuracy of depth with femtosecond
can exceed microkeratome quality but further optimization
is needed. The endothelial morphology appears
unaffected in the presence of laser ablation 150 microns
from Descemet’s membrane. “Femtosecond laser ablation
of the deep corneal stroma is close to being a viable alternative
to microkeratome for donor preparation for DSEK and
DALK. The next major advance we would like to see is to
have a topographic link-up using anterior segment optical
coherence tomography (AS-OCT) for accurate ablation
profiles in reference to the posterior corneal surface. I think
the femtosecond laser for DSEK and DALK are currently
on horizon now,” he said.
Singapore ReLEx Study: Dr Tan discussed the results of
30 ReLEx flex and 10 ReLEx smile cases of which 17 were
analyzed. There was no algorithm adjustment. All cases
were followed up for at least 1 month and 33 for 3 months.
Speaking about the wide range of myopia, he said, “We
went up to -10D and the average mean spherical equivalent
was about -5.5D. The range was up to -9.75D and cylinder
went up to -2.75D.”
At 1 month postoperative, the mean spherical equivalent
was 0.33. This hyperopic mean was good as most patients
were young. And at 3 months postoperatively (33 eyes), the
mean spherical equivalent was 0.22 (1.75 to -0.63). There
was a case of hyperopic surprise and there wasn’t much
myopic regression. Speaking about safety, he said that there
does occur loss of lines. The results though are far better at
3 months. He shared his learning experience about suction
loss in a 30 year old female, -8.75D/-1.25D. According to
him, the ReLEx was stable and predictable without nomogram
adjustments unlike the excimer laser nomograms.
Talking about the reasonable efficacy he said that the results
at 3 months were appreciable with 95% at 1D visual acuity.
ReLEx smile results (6 eyes): These had a full ReLEx
ablation profile, but the flap was only partially opened
(about 1/3) and the lenticule extracted. According to him,
“Enhancement could be done and it was easier.” The
encouraging results seemed better than ReLEx. He further
explained that the advantage of ReLEx smile was the
easier enhancement.“I shifted the hinge to 160 degrees, as
I am a right-handed surgeon,” he said. Comparing these
with ReLEx, he said that ReLEx smile is a bit more challenging.
He feels that ReLEx smile is good in the hands
of surgeons who are experienced. For an average surgeon,
who has not done many cases, there is a learning curve. He
showed the various dissectors they have used in lamellar
surgery and his favored DSAEK forceps. He shared a video
of the ReLEx smile procedure and showed how centration
is the key to visual acuity.
ReLEx experiences and research at SERI: According to
Dr Tan, ReLEx seems to be a promising new modality
which may well challenge the superiority of LASIK, further
clinical studies including direct comparison with LASIK
are underway. Early clinical results with no nomogram
adjustment appear to confirm good refractive efficacy,
predictability, stability and safety though more cases need
to be done. Preliminary results of ReLEx smile are also
highly promising, with major advantages of better tectonic
strength and possibly less dry eye and ocular surface
disturbance. Lastly, the potential reversibility of ReLEx
procedures may be a reality. “We have a cornea wound
healing laboratory at the Singapore Eye Research Institute
and the main role is to explore new surgical and therapeutic
modalities for selective lamellar keratoplasty and corneal
lamellar laser refractive surgery. We do have facilities for
small and large animal primates with dedicated ophthalmic
theatres, surgical microscopes, confocal microscopy, AS-
OCT, immunohistochemistry, range of methodologies like
EM, microkeratome, femtosecond laser and excimer laser
platforms. He also said that the VisuMax platform is a part
of the Translational Clinical Research (TCR) Flagship
Program (TRIOS) funded by Government National
Research Foundation Grant in collaboration with Carl Zeiss
Meditec and discussed the changing trends of selective
lamellar keratoplasty at SNEC.
Storage of lenticules: He discussed the potential of
reversibility of ReLEx and shared that SERI has filed
a patent (#61/382,037) for the technique of storage of
lenticules following femtosecond refractive lenticule
procedures.
SERI studies in rabbit eyes: SERI is experimenting in
rabbit eyes for Femto-LASIK and ReLEx. Dr Tan showed
the comparable results of in-vivo confocal microscopy
for lamellar interface and anterior stroma in LASIK
and ReLEx. He then discussed the ongoing studies to
investigate the various markers for inflammation (CD
11b), cell proliferation (Ki-67), wound healing response
(Fibronectin) and cell death. He showed the ReLExlenticule
re-implantation technique wherein the lenticule
placed on RGP CL and stored at -80 degree centigrade was
replaced in correct anatomical orientation at 1 month after
a flap relift. “We have tested the proof of concept that we
can re-implant at least in rabbits,” he affirmed. He showed
the topographies before ReLEx, 3 days after ReLEx and
3 days and 7 days after re-implantation of lenticule. He
showed the AS-OCT imaging obtained after reimplantation