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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6023_Библиотеки_им_академика_М_И_Перельмана.pdf
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Fig. 19.2 Iris stretching
with Sinskey hooks
Fig. 19.3 Iris retractors
19 Vitrectomy forDicult Retinal Detachment (PVR)
traumatic surgery and less leakage from the trocars. In the case of pseudophakia, the
sclerotomies are placed 3.5mm behind the limbus and in the case of a natural lens
4.0mm. Insert the infusion line in a quadrant without anterior traction. Otherwise
the infusion will be located subretinally. In complicated vitrectomies, we insert
always a chandelier light (four-port PPV) which allows for bimanual dissection of
membranes, bimanual injection of PFCL, and injection of silicone oil under view to
the retina.
A vital point for successful and complication free vitrectomy is a good visualization. Wide-angle viewing systems have a viewing eld of 60° to 130°. They allow for
anterior dissection and limit the need of scleral indentation. The visualization in an
air-lled eye is improved. The stereopsis is however reduced. The conventional con-
tact lens system has a viewing eld of only 20° to 30° and requires scleral indentation. We use the Resight Biom system from Zeiss together with a Zeiss Lumera
microscope.
19.4 Every Surgical Step inDetail
Fig. 19.4 Malyugin ring
19.4.4 Vitreous Staining withTriamcinolone
19.4.5 Vitreous Base Shaving
333
A posterior vitreous detachment (PVD) is usually present in idiopathic PVR.In
contrast, a PVD is not present in diabetic and traumatic PVR.Induce the PVD as far
anteriorly to the vitreous base as possible. The vitreous in PVR is inamed and
therefore a thorough removal is important. We recommend the staining of the vitreous with triamcinolone to assess if a PVD is present and to allow a meticulous shaving of the vitreous base. “Shaving” means that the vitreous cortex is removed to the
surface of the peripheral retina. The settings of the vitreous cutter are a high clip rate
(5000–7500 cuts/min) and a low aspiration rate (200mmHg). Crucial for a successful shaving is a wide-angle viewing system and scleral indentation. Ideally the
scleral indentation is performed bimanually under illumination of a chandelier light.
19.4.6 Membrane Dissection
In general: The removal of preretinal membranes results in relief of preretinal traction. All epiretinal membranes must be removed. Even in the case of retinotomy,
remove all membranes up to the retinotomy edges. If you leave epiretinal membranes, then they will continue to proliferate and cause a tractive detachment. In
contrast, remove subretinal proliferation only if the posterior retina is not attened
under PFCL.Begin with the removal of the membranes located at the posterior pole
and continue with membrane dissection in the peripheral retina (Fig.19.5).
334
Fig. 19.5 In PVR
detachment membrane
dissection starts in the
central posterior pole and
continues in the periphery
19 Vitrectomy forDicult Retinal Detachment (PVR)
Technique of Membrane Staining We rell the dye into a regular 3cc syringe
because the dye can be ejected in more controlled manner (Figs.19.6 and 19.7). In
PVR detachments the membranes are located centrally and peripherally. It is easy to
stain central membranes in a BSS-lled eye because the dye falls down on the posterior pole. This maneuver is, however, difcult for peripherally located membranes.
We stain, therefore, in an air-lled eye. In an air-lled eye, the contact between
membrane and dye is longer and more concentrated before the dye falls down on the
posterior pole. Perform a uid x air exchange, and drop a few drops of the dye
directly on the membranes (Figs.19.8 and 19.9). Wait 30s, aspirate rst the dye
from the posterior pole, and then continue with an air x uid exchange. With this
method, a higher concentration of the dye is achieved and therefore a better staining
of the membranes.
Technique of Membrane Removal The peeling of PVR membranes is technically
very difcult. It requires patience, good visualization, and good instruments.
Centrally located membranes can be removed with one hand, but peripherally
located membranes require bimanual peeling. Our setup is a four-port PPV with
three trocars and one chandelier light.
19.4.7 Removal ofEpiretinal Membranes (Fig.19.10)
A successful membrane removal depends to a large amount on the instrument, even
if you are an experienced vitreoretinal surgeon. You need good delamination instruments and good forceps. Test therefore many different peeling forceps to nd the
one which suits you best.
19.4 Every Surgical Step inDetail
Fig. 19.6 A Charles ute
needle
Fig. 19.7 A 3cc syringe
lled with Trypan blue is
easier to use than an
original syringe
Fig. 19.8 The dye is
dropped on the membrane
335
Fig. 19.9 The vitreous
cavity is lled with air.
This method increases the
concentration of the dye
and enables the staining of
peripheral membranes
Trypan blue
AIR
336
Fig. 19.10 Removal of
peripheral membranes with
endgripping forceps and
straight scissors
19 Vitrectomy forDicult Retinal Detachment (PVR)
For delamination of the membrane, we use a 25G or 27G blunt retrobulbar cannula (Atkinson, Beaver Visitec). Alternatively, you can use a membrane pic (DORC).
For dissection of membranes, three different forceps from DORC are available. In
our experience the 27G endgripping forceps (DORC) is suitable for every tissue
from ILM to thick membranes. Membranes with strong adhesions require stronger
forceps such as the serrated jaws forceps or a strong endgripping forceps.
Vitreoretinal tractions can be cut with straight 25G microscissors (Fig. 19.10)
(DORC, NL, and Eye Tech, UK) and curved 27G microscissors (DORC).
The most difcult surgical maneuver for removal of PVR membranes is the
delamination of the membranes from the retina. This maneuver is even more difcult in the eyes after a silicone oil tamponade. After a silicone oil tamponade, the
membranes are even more adherent to the retina. Delaminate the membrane with an
Atkinson cannula, and create an opening between membrane and the retina. Then
lift the membrane here with a forceps, and move at the same time the delamination
cannula or alternatively a 25Gknob spatula (Eye Tech, UK) backward and forward
through the opening.
The peripheral membranes are very difcult to remove because the retina is
detached and because the membranes are difcult to reach with the instruments.
Instill PFCL to stabilize the posterior retina and facilitate membrane removal. In
addition, peruorocarbon liquids (PFCLs) draw the vitreous base more posteriorly.
This effect facilitates anterior dissection and reduces the chances of retina or vitreous incarceration in a sclerotomy site. Furthermore, it facilitates drainage of subretinal uid through anterior retinal breaks. Important: All breaks must be freed of
traction before they come in contact with the PFCL.Otherwise there is a risk that
the PFCL tracks subretinally.
Subretinal proliferations are present in nearly half of the cases of PVR but rarely
prevent retinal reattachment. Must all proliferations be removed? No, only the sig-
nicant ones. A signicant subretinal membrane is one that will preclude attening
of the retina unless it is removed. Their signicance becomes obvious when PFCL
19.4 Every Surgical Step inDetail
337
is instilled. Remove a subretinal proliferation only if the posterior retina is not attened under PFCL.A special case of a subretinal proliferation is a “napkin ring.” A
napkin ring is a tight annular band near the optic disc. Its removal requires a 360°
retinotomy. See chapter “Traumatic PVR.”
19.4.8 Removal ofSubretinal Proliferations
Before removing subretinal membranes, perform a complete posterior and anterior
epiretinal dissection.
The complete surgery is shown step-by-step in Sect. 12.2.
19.4.9 Retinotomy
Introduction
If despite meticulous transvitreal, epiretinal, and subretinal dissection, the retina
remains foreshortened preventing an attachment of the retina with the retinal pigment epithelium; the surgeon should perform a retinotomy or retinectomy in order
to relax the retina. Retinotomy involves incising the retina, whereas retinectomy
involves excising the retina. The peripheral retina is cut parallel to the ora serrata
(180°, 270°, or 360°), and the retinotomy edges are treated with laser photocoagulation in order to reattach the retina. See Diagram 1.
Retinotomy could be performed in a radial fashion, but most commonly it is
done circumferentially, parallel to the ora serrata. Most PVR cases can be managed
without retinotomy/retinectomy. We almost never use it in the rst surgery, except
for the penetrating injuries with PVR and incarceration of the retina in the penetrating wound. The circumferential retinotomy in repeated surgery for idiopathic PVR
detachment is performed in the area with persistent contraction of the retina usually
affecting the two lower quadrants, due to the physical property of the 1000 cSts silicone oil that is regularly used for the rst surgery. This silicone oil is lighter than
water and therefore is leaving some space lled with aqueous inferiorly thus tamponing better the upper two quadrants where recurrent detachment almost
never occurs.
The relaxing retinotomy consists of three main surgical steps:
1. Ora parallel diathermy
2. Retinotomy
3. Removal of anterior retina (retinectomy)
The most common problem with the retinotomy is underestimation of the necessary size of the tissue to be removed so that contraction persists. The most common
size of retinotomy is 180° tapered to the two lower quadrants and extending from 3
over 6 to 9 o’clock. A 360° retinotomy is seldom and may be required in penetrating
injuries with incarceration of the retina and PVR stage D.It is usually followed by
338
19 Vitrectomy forDicult Retinal Detachment (PVR)
some distortion of the retina after reattachment and requires relocation of the retina
using the ute needle with silicone tip in order to reestablish its normal anatomical
position. The complete surgery is shown step-by-step in Sect. 12.3.
19.4.10 Instillation ofPFCL
As next step, we perform an attachment test: Fig.19.11. For an attachment test, you
can use PFCL or air. PFCL attaches the retina with its gravity. Air attaches the retina
with its surface tension pressure. If the retina is attached under PFCL, then perform
a PFCL against air exchange and check if the retina is also attached under air. If this
is the case, then the retina will also be attached under a gas tamponade. But the
retina is not necessarily attached under a silicone oil tamponade because the surface
tension pressure of silicone oil is lower than the surface tension pressure of air.
Injection of PFCL We inject PFCL bimanually; one hand holds the PFCL syringe
and the other hand holds the Charles ute needle. Hold the tip of the PFCL cannula
in the middle of the vitreous cavity and inject a little bit. Then start to inject the
PFCL at the posterior pole, and keep the tip of the cannula always in the PFCL
bubble in order to prevent small bubbles (Fig.19.12). Aim never toward the macula
or a retinal break. The PFCL bubble becomes bigger and bigger; pull the PFCL cannula slowly backwards but the tip remains constantly inside the bubble.
Fig. 19.11 Opposite
mechanisms of action of
PFCL and air in a
BSS-lled eye. Air lls the
globe from anterior to
posterior. PFC lls the
globe from posterior to
anterior
Air
BSS
PFC
Char
needle
19.4 Every Surgical Step inDetail
339
Fig. 19.12 Work
bimanual. The left hand
releases BSS with a
backush instrument and
the right hand injects PFCL
BSS PFCL
les flute
19.4.11 Laser Photocoagulation
The aim of laser photocoagulation is a long-term stabilization of the reattached
retina. Laser photocoagulation causes less RPE cell dispersion than cryotherapy and
consequently less PVR.In addition, laser photocoagulation induces no disruption of
the blood-aqueous barrier.
Technique of Laser Photocoagulation
Laser photocoagulation can be performed in the PFCL-lled eye or in the air-lled
eye. Apply the laser effects conuently surrounding all retinal breaks. Our laser
power for retinal breaks with an argon laser (Iridex, CA) is power: 100–300mW;
duration: 200msec; and interval: 300msec.
Surgical Pearls No. 89
Laser cerclage ≠ encircling band (Fig.19.13). Both, an encircling band and a laser
cerclage, create a barrier for tears located anterior to the barrier. In addition, an
encircling band creates an indentation of the retina which results in a relaxation of
the shortened retina. A laser cerclage, however, does not create an indentation and
can therefore not help in relaxing a shortened retina. This is important for PVR
detachments with intraretinal PVR and a shortened retina.
Surgical Pearls No. 90
Cryopexy versus laser photocoagulation: Cryopexy creates PVR; this is especially
the case if the posterior hyaloid is detached. In vitrectomy for retinal detachment
surgery, laser photocoagulation is recommended because it induces less PVR.
340
Fig. 19.13 In the case of
a 360° laser cerclage, there
is a risk of a laser necrosis
at the inferior pole due to a
lack of tamponade
19 Vitrectomy forDicult Retinal Detachment (PVR)
360° lasercerclage
Silicone oil
No tamponade
High detachment risk
19.4.12 Prepare theAnterior Chamber
Before nalizing surgery with the intraocular tamponade, the anterior segment must
be prepared (Figs.19.14 and 19.15). In the case of 1000 or 5000 cSts silicone oil,
an inferior Ando iridectomy is performed to enable a ow of aqueous from the inferiorly located aqueous phase in the posterior chamber to the anterior chamber. In the
case of a Densiron 68 tamponade, a superior iridectomy is performed to enable the
ow of aqueous from the superior located aqueous phase in the posterior chamber
to the anterior chamber. Not in all cases an iridectomy must be performed. In a normal pseudophakia situation, an iridectomy is not necessary. An iridectomy is however necessary in aphakia, in 360° posterior synechiae and in partial zonular lysis.
In the aphakic eye, the inferior peripheral iridectomy prevents a pupil block by the
anterior surface of silicone oil. Face-down positioning for the rst 24h is necessary
to ensure the reformation of the anterior chamber.
In addition, you can inject methylcellulose into the anterior chamber to prevent
an immediate postoperative ow from silicone oil into the anterior chamber. The
methylcellulose causes no IOP increase in case of a silicone oil tamponade.
19.4.13 Tamponade
PFCL Removal and Tamponade
For gas tamponades, a PFCL x air exchange is routine. For silicone oil tamponades
two surgical techniques exist: (1) a PFCL against silicone oil exchange and (2) a
PFCL against air and then an air against silicone oil exchange. We use a PFCL
against silicone oil exchange in traumatic retinal detachments. Otherwise, we use
always a PFCL against air exchange.
Slippage is a complication which occurs in giant tears or retinotomies. If subretinal uid is present at the posterior pole and the eye is lled with gas and the patient
a
b
19.4 Every Surgical Step inDetail
Fig. 19.14 Ando
iridectomy with vitreous
cutter
341
Iridectomy
1000 cSt silicone oil
Iridectomy
Fig. 19.15 An inferior (a) or superior (b) iridectomy depending on the silicone oil
Aqueous
Aqueous
Densiron 68
is located face down, then a slippage at the posterior pole with macular folds may
occur. To avoid the slippage, use PFCL and perform a thorough aspiration of uid
at the giant tear edges and avoid face down positioning directly after surgery. In silicone oil, slippage with macular folds does not occur. The reason for this is that the
surface tension pressure of silicone oil is too low to press away the uid at the posterior pole; the uid is resorbed by the pigment epithelium and the retina slowly
reattaches.
PFCL Against Silicone Oil Exchange: (Fig. 19.16) For this step a chandelier
light is not required. If you exchange PFCL against silicone oil, one hand aspirates
the PFCL, and the other hand holds the light ber while the silicone oil is injected
with the infusion line.