Osher: The last video shows that anterior chamber
and posterior capsule stability are advantages
of operating at physiologic intraocular pressures.
I've been a disciple since introducing slow-motion phaco
with low parameters in the early 1980s when I worked
with an Italian company, Opticon,
to introduce surgeon control rather than machine-controlled
parameters.
The next video confirms the safety of this approach
by examining anterior vitreous face behavior,
produced by Doctors Scarfone, Riera, Rodriguez,
and Epelbaum from Argentina.
Scarfone: Cataract surgery is one
of the most common procedures performed worldwide.
It is also one of the oldest. Nowadays,
it's a very safe procedure
as a result of improved surgical techniques
and technology. Efficient fluidic settings are necessary
to obtain a safe and stable operating space inside the eye.
One primary factor in maintaining a safe
and stable anterior chamber is controlling
intraocular pressure,
ideally to stay within
or near physiological range.
Surgeons adopt different approaches based on their personal
experience, the technology they have,
their surgical technique,
and the type of eye to be operated on.
That can be differentiated by the use of high, medium,
or low aspiration flow rates,
total height, or IOP and vacuum.
Advanced or expert phaco surgeons preferentially choose higher
settings, therefore obtaining a very fast surgery
and reduced ultrasound energy consumption.
However, there's a fundamental question rarely asked
or questioned about whether this normally used higher
settings can potentially cost serious intraocular damage
During phaco surgery,
at the settings, the IOP can increase
to approximately 100 mm Hg
or even more. In another perspective, burying an IOP at
90 mm Hg
in surgery is like experiencing an episode
of acute angle closure crisis, which is known
to cause extensive damage to ocular structures.
Keep in mind that the average ocular physiological pressure
is about 16 mm Hg.
Intraocular veins function as stalling resistors.
The pressure before leaving the eye must be higher than the
IOP or the flow stops.
The mean ocular perfusion pressure is about 60 mm Hg
and is calculated
as two-thirds mean arterial pressure.
IOP during surgery influences intraocular vascular flow, and
therefore our pressure setting must be
below mean ocular perfusion pressure.
We have the feeling that we are very concerned about the
surgeon's comfort zone and from so much thinking
and thinking about it,
we have forgotten the eye's comfort zone, violating normal
physiological parameters without any concern about the
damage that could occur with it.
Beyond corneal damage
or posterior capsular rupture,
not much attention can be paid to the effects
that phacoemulsification
and its fluidic parameters can have on the posterior
segment structures,
even at the cellular
or molecular level. We propose to call that the damage
that we can't see.
Kawasaki and colleagues found that continuous elevation
or abrupt fluctuations
of IOP within the anterior chamber can lead
to anterior hyaloid membrane detachment.
Vaishali Vasavada
and colleagues show in real time
that the anterior vitreous face can be ruptured despite an
intact posterior capsule by the use
of higher aspiration flow rate
and irrigation bottle height,
Anisimova et al confirmed the hypothesis that
with age-related or pathologic weakening
of the retrolenticular apparatus precipitated
or worsened by the hydrodynamic fluctuation
during cataract surgery,
the normal vitreolenticular interface addition is disturbed,
causing an anterior vitreous detachment.
In this patient, the preoperative full-range
anterior-segment OCT shows an intact vitreolenticular interface
During an eventful phacoemulsification,
at the end of the aspiration of cortical remains,
lenticular fragments were observed
behind the posterior capsule.
We have seen in these circumstances that the posterior capsule
and the entire capsular bag become much more fragile
and flaccid, making polishing
of the posterior capsule very difficult.
We believe that this greater fragility is produced
by the loss of support that the interior vitreous
and its interior hyaloid membrane give
to the posterior capsule.
Remember that the posterior capsule alone measures only 2.8
microns thickness. In a 24-hour postoperative control,
the AC full-range OCT rebuilt changes in the anterior
vitreous with a detachment of the anterior hyaloid membrane.
These findings are consistent with studies by Kawasaki, Vasavada,
and Anisimova.
Libor Hejsek et al revealed
that using the bottle height at 100 centimeters,
a very popular bottle height setting,
the IOP exceeded 60 mm Hg up to 85%
of the time of the phacoemulsification
procedure. Zhenni Zhao et al. Extensive cellular
and molecular damage was observed in the retinas
at 90 mm Hg
IOP setting,
including cell apoptosis mainly in the outer nuclear layer,
activations of microglia cells,
blood retinal barrier impairment, and retinal inflammation.
In addition, setting below 45 mm Hg IOP
generally causes minimal,
sometimes undetectable damage.
Tong Ding et al showed a correlation
between the infusion time, infusion pressure,
and the changes in retinal structures
during cataract surgery.
When the IOP is too high, anterior-segment ischemia would
appear and lead to prostaglandin release,
which finally may result in cystomacular edema.
We must be aware that there is damage
that we do not see microscopically.
Beyond the extra care required about the most vulnerable
and pathological eyes,
this concept is extremely important
because the growing trend of phacoemulsification
for purely refractive purposes
where we operate completely healthy eyes
and makes the concept of risks
and potential damages much more critical and less tolerable.
Therefore, we are facing a new paradigm
that means prioritizing the comfort zone of the eye.
In that sense, there's extensive scientific evidence
that shows that we must migrate toward lower
or moderate fluidic settings close
to the physiological parameters of the eye,
despite the surgeon's comfort zone.
From a medical and ethical point of view,
we strongly recommend to operate with intraocular pressures
below 45 mm Hg.
This change needs a critical switch in the
surgeon's mindset.
Today, with newly available
and advanced phaco machines with active fluidics,
where the height of the irrigation bottle is not crucial,
this concept of moderate- parameter phaco is quite feasible
in practice. There is no technical barrier.
Surgeons can have a new fluidic setting
that addresses their own needs
and those of normal ocular physiology. They just have
to find their new comfort zone.
Cavalho: Dear Bob, in my challenging cases,
I always find a solution that I learned from Video Journal.
I want to congratulate you
for all your efforts in bringing together cases
and solutions from all over the world in excellent videos,
and also thank you for a kind partnership
with the Brazilian Association
of Cataract and Refractive Surgery.
Congratulations on this 40th anniversary of Video Journal
of Cataract, Refractive, and Glaucoma Surgery.
Thank you, my friend Bob Osher. [Osher] Thanks, Durval.