103 Vi

Mastering phaco prechop

Akahoshi T
Tokyo

Phaco prechop is a technique of nucleofracture performed
under the viscoelastic material, prior to the phacoemulsification.
By this simple procedure, the nucleus can be divided without
grooving nor sculpting and thus, the following phacoemulsifica-
tion can be markedly facilitated. For prechopping the nucleus, a
special dividing instrument named phaco prechopper is used.
According to the hardness of the nucleus, most appropriate pre-
chopper should be selected. For a soft nucleus such as grade 1 or
2, a Combo Prechopper (ASICO AE- 4284) is most suitable to be
used by the Karate Prechop technique. This prechopper has a
blade of different shape on each side, one is a sharp angular blade
and the other is blunt rounded. The sharp blade is used for pre-
chopping a grade 2 nucleus. The blunt blade is used not only for a
softer nucleus, but also for ascertaining the complete nuclear
division of harder nucleus close to the posterior capsule. For the
nucleus harder than grade 3, a Universal Prechopper (AE- 4282) is
used together with a Nucleus Manipulator (AE- 2530) to reduce
the stress on the ciliary zonules and lens capsule. The conventio-
nal Sharp Prechopper (AE- 4281) is used only for a very hard
nucleus such as grade 5. To protect the corneal endothelium with
Viscoat and Provisc by the soft shell technique, to make a com-
plete capsulorhexis and to perform sufficient hydrodissection are
the three important prerequisites for the prechop technique. It is
also important to perform the complete nuclear division reaching
to the posterior capsule. Most of the nuclei can be prechopped by
a prechopper alone, however, there are several cases in which the
phaco prechop should not be performed with a prechopper alone.
These cases include, eyes with an incomplete capsulorhexis, har-
der nucleus and weak ciliary zonules. For these cases, the nucleus
should be sustained by the nucleus manipulator during insertion
of the prechopper. The prechopped nuclear fragments are phacoe-
mulsified at high vacuum and high flow setting of the phaco
machine. I usually use Alcon Legacy ver 3.12 with a specially
modified flared ABS tip attached on the MaxVac cassette and high
infusion irrigation sleeve. At 500 mmHg+ vacuum and 60 ml/min
flow rate at 110 cm bottle height, prechopped nucleus can be
phacoemulsified quite easily and rapidly by a single handed tech-
nique. For the soft and medium nucleus, a 15 Hz pulse mode is
usually used. For the harder nucleus, AdvanTec burst mode is
most effectively used with a NeoSoniX handpiece attached with
a specially prepared flared ABS tip. Compared with the conven-
tional divide and conquer technique, the U/S time was reduced to
less than 10 % by the phaco prechop and ultrahigh vacuum pha-
coemulsification. As the U/S time is shortened, there is no thermal
burn nor mechanical damage of the wound. The clear corneal
incision can be easily self-sealed by simply increasing the intra-
ocular pressure with BSS. Phaco Prechop is the most effective and
easy nucleofracture technique to facilitate the speed and safety of
the phacoemulsification.



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