Very dense and hard nuclei

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16 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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IC
-
102:
Strategies for Very Dense Nuclei and other
Challenging & Complicated cases; a Video Course


Micro
-
coaxial Torsional Phaco for challenging cases; Tips
& Settings


Khiun Tjia MD


Intrepid FMS

The Intrepid FMS® has a significant lower compliance
tubing than the original FMS.

Contraction/expansion of aspiration tubing in response to (high vacuum) occlusion
break is a main contributor to surge flow. Surge flow is the main cause of anterior
chamber instability. It is therefore very logical to minimi
ze surge flow by reducing the
compliance of the aspiration tubing.

With Intrepid FMS, surge flow volume on occlusion break is significantly lower than
with the original FMS.

At the moderately high vacuum levels 300H
g
currently used with Torsional
ultrasoun
d, the surge flow volume is extremely low with Intrepid FMS, resulting in
very good anterior chamber stability and a further increased margin of safety.


The use of Intrepid FMS is highly recommendable in complicated
phaco surgery


Very dense and hard nuc
lei


Tip choice for Torsional ultrasound and Dense nuclei


For very dense nuclei, 45º bevel tips are more efficient compared to 30º bevel tips.

The 45º tips have a larger surface and make the nuclear pieces tumble around their
axis whilst being emulsified.

30º tips drill more easily into the nucleus (lollipop) and
emulsification halts when the sleeve obstructs further movement.



Our experience with Traditional Longitudinal ultrasound and very dense nuclei is that
Flared Tip designs were prone to potentia
l clogging of the tip. Clogging of a tip could
lead to insufficient cooling of the tip and possible heating / burn of the corneal tunnel.


Because of the sideways ultrasonic movement of a tip with Torsional ultrasound, the
nucleus is emulsified in a differ
ent manner. The nuclear material at the tip and inside
of a flared phaco tip is probably less emulsified compared to Longitudinal ultrasound.
There is also no significant repulsion and subsequent repositioning of the nucleus
relative to the tip.

This could

be an explanation for the higher incidence of clogging of Flared Tip
designs with Torsional ultrasound.


If a surgeon still prefers to work with a
45 mini
flared tip, a
high minimum amplitude of
about 60
-
70% (software 2.03 version) should be used or a
mix
of longitudinal and
torsional ultrasound to reduce the potential for clogging of the tip.

A Tapered Tip design rarely clogs, even with dark brown nuclei. Microtip has identical
dimensions from Tip end to Tip shaft and has theoretically no chance for cloggi
ng at
all.


Personally, I prefer to use a
45 Kelman Micro

Tip for cataract cases with very dense
nuclei.

Cataracts with less nuclear density can also be handled with Mini Flared Tips.

In the rare case of a sign of stalling or clogging of a Mini Flared tip,

I use a mix of
Torsional and Longitudinal ultrasound , which I have preset in a separate grade.


OZil IP
S
oftware


In September 2009
,

a software upgrade was released.

OZil IP software allows the
user to momentarily supplement torsional amplitude with

very brief bursts of
longitudinal ultrasound when a programmable vacuum threshold is exceeded. These
short bursts of conventional ultrasound help to minimize occlusions and hence further
improve fluidic stability.
They

also help to keep nuclear material at

the ideal position
of the phaco

tip end, where the shaving action of
t
orsional ultrasound
occurs
.

The
OZil IP feature can be enabled for each individual procedure step and for each
cataract grade.


Cracking
or Chop Technique

for Dense Nuclei

Another chall
enge of handling Dense Nuclei cases is the nucleus disassembly
before emulsification. Although my routine procedure still involves a modified Divide
& Conquer technique (Fast Crack Phaco), I switch to a Chop technique for very
dense and rubbery nuclei, w
hich are very hard to divide in quadrants by a
conventional cracking maneuver. A classic horizontal Nagahara Chop technique is a
good option in my experience to chop the nucleus in multiple smaller pieces.

Vertical Chop techniques are also widely used. The

rounded Olson chopper
combines efficacy with safety and is a very effective and easy instrument for vertical
chop.


Personal Settings recommendations (
45 Kelman Micro

Tip

+

Ultra
sleeve)

or 45
Kelman Tapered Tip
:

2.2


2.4 mm

incision

for very dense nuclei



Chop, for impaling and chopping the nucleus only:

Bottle height :

9
0 cm


Aspiration Flow :

25

ml/min
fixed


Vacuum :


5
0
0mmHg fixed

Power :


Burst Mode,
2
0msec, 50% Fixed Longitudinal US


Quadrant Removal, for emulsification of the nuclear pieces:

Bottle height :

9
0 cm


Aspiration Flow :

1
5 ml/min
linear


Vacuum :


30
0mmHg fixed

Power :

Continuous mode,
minimum 50%
linear
to maximum
100%

amplitude

Torsional Ultrasound







Personal Settings recommendations (
45 Miniflared

Tip

+

Ultra
sleeve):

2.2


2.4 mm

incision

for very dense nuclei


Chop, for impaling and chopping the nucleus only:

Bottle height :

9
0 cm


Aspiration Flow :

25

ml/min
fixed


Vacuum :


5
0
0mmHg fixed

Power :


Burst Mode,
2
0msec, 50% Fixed Longitudinal US


Quadrant Removal, for emulsification of the nuclear pieces:

Bottle height :

9
0 cm


Aspiration Flow :

1
5 ml/min
linear


Vacuum :


30
0mmHg fixed

Power :

Continuous mode,
minimum 60%
linear
to maximum

8
0%

amplitude

Torsional Ultrasound


Low Fluidics
parameters strategy for
Challenging Cataract surgery with

Torsional

U
ltrasound


Challenging and complicated cases like:


-

Zonular weakness / partial dehiscence

-

Posterior capsular rupture

-

Floppy iris syndrome

-

Corneal endothelial dystrophy

-


s
hare one common
problem: Higher intracameral fluid streams have a negative effect
on the outcome of these procedures.


High Flow in the anterior chamber disadvantageous

A high Aspiration Flow will inadvertently attract vitreous or a floppy iris to the
phacotip
, which can
lead to further complications and potential visual loss
.

In endothelial dystrophy cases, high flow and turbulence in the anterior chamber will
evacuate viscoelastic substances, which protect the fragile corneal endothelium from
further damage by ultrasoun
d energy
.


Also, the d
irect impact of bouncing nuclear fragments and excessive fluid turbulence
by itself

can also cause endothelial cell loss with subsequent corneal
decompensation.

High vacuum setting possibly dangerous

A high vacuum setting will cause s
ignificant Surge flow on occlusion break with
anterior chamber instability as a result. Such a sudden chamber pressure change
c
an

destabiliz
e a complicated situation. (e.g. in case of a capsular rupture,

nuclear
pieces dropping into the vitreous or additio
nal zonules tearing from their base
in a
zonular dehiscence case
)
.





Low Fluidics settings mandatory for successful outcomes

Low fluid dynamics settings are mandatory for a successful outcome in these cases.

A
low aspiration flow of 20 ml/min or less and a low bottle height helps to prevent
vitreous or iris to be caught by the phacotip.

A

low/
moderate

Vacuum setting of
200
mm Hg
will
show no
surge flow on occlusion
break

and less pressure variance during the proc
edure
.

In combination with the low
compliance Intrepid FMS, the anterior chamber will remain very stable after occlusion
break.


Very low fluidics settings still very effective

with Torsional ultrasound

With the use of Torsional ultrasound, a very low aspi
ration flow setting of 20ml/min or
less, a bottle height of 50 cm

and a low vacuum setting of
25
0
mmHg or less, the
efficiency of Torsional ultrasound for nucleus emulsification is still amazingly good.


In the case of weak zonules, a posterior capsular rup
ture or a floppy iris, the greatly
reduced fluid turbulence will help to prevent vitreous or floppy iris to be drawn to the
phacotip.

A dispersive viscoelastic, which is injected to push back vitreous or iris (or to
sequester a nuclear piece to prevent it

from falling into the vitreous), will not be
aspirated easily.
In this way, a safe working distance can be maintained between the
phacotip and vitreous or floppy iris.

This
will help the surgeon to control very difficult situations and prevent complicati
ons

and

t
he surgeon will feel much more confident in handling these complicated cases.


Personal experience

Posterior capsular rupture

I have had to deal with remaining nuclear quadrants after an early posterior capsular
rupture on several occasions.

After

stabilizing the situation by injecting Viscoat (Alcon laboratories) behind the
nuclear pieces, I always try to bring one quadrant superior to the iris plane with a
bimanual technique (Injecting Viscoat behind the piece with one hand and a second
instrumen
t for manipulation of the piece centrally and upward into a safe zone above
the iris plane)

I then introduce the phacotip underneath the quadrant and emulsify it very slowly and
in a very controlled fashion without washing out the viscoelastic underneath
.


Personal Settings recommendations (
MiniFlared

Tip

+

Ultras
leeve):

2..2 mm incision

for posterior capsular rupture


Quadrant Removal, for emulsification of the nuclear pieces:

Bottle height :

5
0 cm


Aspiration Flow :

1
2
ml/min
linear


Vacuum :


2
0
0mmHg

fixed

Power :

Continuous mode,
minimum 35%
linear
to maximum
8
0%

amplitude

Torsional Ultrasound


I bring every quadrant into the safe zone by injecting additional viscoelastic and
emulsify them one by one without any significant fluid tu
rbulence or pressure drops.



Zonular weakness & Floppy iris

For Zonular weakness and Floppy iris cases, I used similar fluidics settings to
minimize fluid streams and pressure variance
. I have been able to complete all
procedures without any major
problems.



Corneal endothelial dystrophy
: Use of Viscoat highly recommendable


Personal Settings recommendations (
MiniFlared

Tip

+

Ultras
leeve):

2..2 mm incision

for corneal endothelial dystrophy


Quadrant Removal, for emulsification of the nuclear pieces
:

Bottle height :

75

cm


Aspiration Flow :

1
5 ml/min
linear


Vacuum :


30
0mmHg fixed

Power :

Continuous mode,
minimum 35%
linear
to maximum
8
0%

amplitude

Torsional Ultrasound


At the end of quadrant removal, a thick layer of Viscoat

is still
visible which reassures
me that the endothelial cells are protected during the entire procedure.