Cool laser blasts way to micro-incision
NICE - Cataract extraction using the Dodick Laser PhotolysisTM system
(ARC, Switzerland) is as fast as conventional ultrasound phacoemulsification
and allows the surgeon to work with ultra-small incisions with minimal
trauma and no risk of burns to the eye.
More than that, new specially designed IOLs also allow for completion
of the procedure without enlarging the wound, inventor and developer
Jack Dodick MD, FACS told the XX ESCRS Congress.
He noted that the Dodick Laser Photolysis system is now being used
in over 100 centres worldwide and over 5,000 cases have been performed
with it. It is currently the only FDA-approved laser system for
"The Dodick Laser Photolysis system for cataract removal should
no longer be categorised as experimental or investigational but
as alternative to ultrasound phacoemulsification," he asserted.
The laser cataract removal system uses an indirect Nd:YAG laser
to generate shock waves by striking a titanium target at the end
of an aspirating hand piece.
The flexible quartz fibre probe does not generate heat, which eliminates
the risk of corneal burn. As a result, the probe may be inserted
through a 1.4 mm or smaller incision, since no sleeve is necessary.
New intraocular lenses which can be inserted through such tiny incisions
have provided further impetus for the adoption of the micro-incision
technology, Dr Dodick pointed out.
He noted, for example, that German specialist Wolfram Wehner MD
currently performs 80% of his cataract procedures from beginning
to end with ultra-small incisions using Dodick Photolysis and AcriTec™
IOLs which he inserts without enlarging the wound.
"Before these new lenses were available, people would ask what
the advantage was of being able to remove a cataract through a 1.4
mm incision when you are going to have to implant the lens through
a 3.0 mm.
"Now, like history repeating itself with ultrasound phacoemulsification,
there is a small-incision lens and that is an excellent motivation
to adapt to the newer technology," he said.
Dr Wehner uses a bi-manual procedure. He inserts the combination
laser/aspiration probe, which has an outside diameter of 1.2 mm,
through a 1.4 mm incision.
In a second 1.4 mm incision, he inserts a special irrigating chopper
which he designed himself called the Wehner Spoon, Dr Dodick explained.
In his first 849 cases using the Dodick photolysis system, Dr Wehner
was able to complete the procedures in cataracts between grades
one to four from beginning to end in under 10 minutes and in grades
one to two in nine minutes or less.
"One of the biggest misconceptions about laser cataract surgery
is that all lasers are the same and it is slow. It is not, at least
with this technology, and the procedure time drops dramatically
with new high vacuum tubing advances.
"So I can make a categorical claim that this procedure is as
fast and sometimes faster in 1+ and 2+ cataracts," Dr Dodick
In addition, the laser system releases very little energy into the
eye. In 225 consecutive cases measured by Andrew Miller MD in New
York, 185 cataract extractions required 1.0 J or less of laser energy,
38 required 1.0 J to 2.0 J and only two required more than 2.0 J.
"The only report in the literature concerning ultrasound energy
is a four-year-old study by DeVries and at that time cataract extractions
involved between 700 J and 1,100 J depending on the technique.
"I'm sure that has dropped tremendously with the focus on high
vacuum but the input energy with the laser cataract removal really
is infinitely small," Dr Dodick noted.
The Dodick Laser Photolysis system has a Venturi phacoemmulsifation
unit. It also has combined features for posterior segment surgery
including vitrectomy light pipe and silicone oil injection.
Recent modifications include a smaller 0.9 mm probe now undergoing
beta testing that may be inserted through a 1.0 mm incision. The
new probe is completely disposable after one use and should become
available in the first quarter of 2003.
Another advance which has now been implemented is new high vacuum
tubing. The tubing provides greater vacuum creation and 'hold' with
less total fluid flowing through the eye and has increased both
the efficiency and safety of the procedure.
"Most of the publications on endothelial cell loss after ultrasound
phacoemulsification are based on the premise that it correlates
with the amount of energy put into the eye but I don't think that
that is necessarily so. I think the amount of fluid passed through
the eye is a contributing factor," Dr Dodick said.
One surprising and as yet unexplained possible advantage the laser
system may have over ultrasound is a reduced rate of posterior capsule
In a study carried out by Lindsey Smithen MD in New York, the PCO
detection and treatment rates in 100 eyes undergoing cataract removal
with Dodick Photolysis were only 1.0%. That compared with PCO detection
and treatment rates of 7.5% in 100 eyes undergoing conventional
"We don't know why this occurs but we are investigating it
further. Perhaps the laser also has an effect on the germinal epithelium
in the equatorial zone of the eye.
"And while these are early days, it's worth pointing out that
we have here a technology that could enable us to purposely ablate
the germinal epithelial cells in the periphery after cataract removal.
In this way, we might perhaps cure PCO and that's very much on our
front burner right now," Dr Dodick said.
One argument against learning to operate the Dodick Laser Photolysis
system is the development of enhanced forms of ultrasound phacoemulsification
which also allow for micro-incision cataract removal.
Several proponents of such systems voiced their scepticism about
the usefulness of the laser method when ultrasound can achieve the
same results and do so in cataracts of every degree of hardness.
Spanish ophthalmologist, Carlos Verges MD told the conference that
he has used all three types of laser cataract removal procedures
- the Dodick Photolysis System, the Nd:YAG laser direct ablation
and the erbium laser.
However, in his opinion the broader applicability of newer ultrasound
systems, particularly the AMO Sovereign WhiteStarTM, made them easier
to use than the laser systems.
"For me, the best arrangement is the one that is most simple.
If I have one system that enables me to perform all kinds of cataracts,
it is better. We complicate all our surgery if we need more than
one system even if it is in the same place," Dr Verges said.
Richard Packard MD, who is also a proponent of the WhiteStar, concurred
with Dr Verges and suggested that the time when laser could have
contributed in a useful way to cataract surgery may have already
"I think we need to analyse why laser phacoemulsification exists
at all. The first time I saw Dr Dodick describe the procedure was
actually in the late 1980s. It was of interest then because of the
way ultrasound was performed at that time and because laser at that
stage was going to give us the possibility of small-incision surgery.
"Since that time ultrasound has moved on and as a result most
if not all of the arguments for laser cataract removal have virtually
disappeared," Dr Packard said.
Israeli ophthalmologist Ehud Assia MD suggested the strongest point
in favour of laser cataract removal was its novelty.
"Currently, the only advantage for laser machines is their
name. Patients love lasers. Otherwise, ultrasound does better in
all other parameters but the future will tell which type of system
prevails," Dr Assia said.
Dr Dodick countered these arguments by pointing out that his laser
system is a rapidly developing technology and can already perform
as well if not better in the removal of most cataracts. In addition,
he noted that the reduction of energy, less risk of PCO and absolutely
no risk of corneal burns were advantages that could not be denied
nor for that matter could be deliverable by ultrasound.
Many surgeons are using the WhiteStar programming with a sleeve
and many have noted that their wounds seal better. This re-introduces
the idea of low-grade corneal burns existing at a higher rate than
clinically noted and may be a source of unexpected postoperative
"I'm a student of history and ultrasound was invented at my
hospital by Charlie Kelman in 1967. I was there on the day the first
ultrasound procedure took 61 minutes of ultrasound time and four
hours and five minutes of surgery.
"Many surgeons took the position that there was no reason to
bother. The remarks of Dr Packard remind me so much today of those
same comments made of phacoemulsification some 35 years ago. So
I have the patience to develop and adopt a promising new technology,"
Dr Dodick said.
He added that it will not be for a handful of ophthalmologists to
decide which technology will bring true reproduceable microincision
cataract surgery. The best technology will obviously prevail, he