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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_6023_Библиотеки_им_академика_М_И_Перельмана.pdf
172
8 Surgical Management ofDiabetic Retinopathy
8.4.3 Surgical Techniques andIntraoperative Precautions
When preoperative B-scan ultrasonography indicates mild posterior pole proliferation, the procedure is generally straightforward. The surgical approach typically
follows these structured steps:
(1) Central Vitrectomy and Media Clearing
Upon inserting the endo-illuminator and vitrectome, if the metallic tip is visible
through the media, vitrectomy may proceed directly using a wide-angle viewing
system. However, in cases of dense VHwhere the visual axis is completely obscured,
the anterior vitreous must rst be resected under direct microscopic visualization.
This initial clearance creates a safe workspace.Throughout this stage, meticulous
care is required to avoid iatrogenic lens injury and to maintain a safe distance from
the underlying retina (Fig.8.6).
If the optic disc and retinal vasculature are clearly visible at this stage, it typically indicates a highly liqueed vitreous with complete PVD, generally leading to
a straightforward procedure. Conversely, if the posterior pole remains obscured,
extreme caution is mandatory to prevent iatrogenic retinal injury from the
vitrectome.
Fig. 8.6 Anterior
vitrectomy under direct
microscopic visualization.
(a) To prevent blood from
entering the anterior
chamber, rst inject
viscoelastic agent into the
anterior chamber to ll the
entire space, under
microscopic
transillumination, the
vitrectome resects the
retrolental vitreous on the
same side. (b) The
vitrectome is switched to
the opposite sideto clear
the remaining peripheral
vitreous, markedly
restoring visualization of
the posterior segment
a
b
8.4 Surgical Treatment ofVitreous Hemorrhage
173
(2) Vitrectomy Starting from the Superior Vitreous Cavity
Surgeons should remain vigilant to the possible presence of a mobile, detached
retina below. During advancing the vitrectomy, even a minor error can result in
irreversible, extensive retinal loss. As a general principle, vitrectomy should be
rstperformed in the superior vitreous cavity (between the 10 o'clock and 2 o'clock
positions). In the event of an iatrogenic retinal tear, superior breaks are typically
more manageable than those located elsewhere.
(3) “Finding the Beacons in the Mist”
The optic disc and retinal vasculature serve as essential "beacons" during VH surgery. Identifying these landmarks claries the surgical eld and provides reliable
anatomical reference points. This principle is fundamental across all VH cases—
whether secondary to RRD, polypoidal choroidal vasculopathy (PCV), or PDR—
and must be prioritized consistently.
The surgeon should search for vascular clues through clear gaps in the vitreous.
The vascular architecture serves as a diagnostic guide: a standard anatomical course
suggests attachment, while a displaced or anteriorly shifted vascular pattern is a
hallmark of retinal detachment (Fig.8.7).
(4) Inducing Posterior Vitreous Detachment (PVD)
The presence or absence of PVD in cases of VH can be highly deceptive; novice
surgeons must remain vigilant toprevent frommisjudgments.If a complete PVD
ab
Fig. 8.7 Landmark identication and surgical safety. (a) Partial clearing reveals the optic disc
(green dashed line) and retinal vessels (green arrows) at a standard depth. (b) Overlying clots
obscure the disc (green dashed line), and vessels (green arrows) appear displaced toward the surgeon. In this case, the aspiration function of the vitrectome should be used rst to create a safe
distance between the vitreous and retina before resecting the vitreous
174
8 Surgical Management ofDiabetic Retinopathy
exists, the posterior pole is typically clear of dense adhesions; any residual blood
can usually be aspirated using a ute needle or the vitrectome. Conversely, if hemorrhage remains rmly adherent to the posterior pole, it signies tight vitreoretinal
adhesion. In such instances, TA should be injected to visualize the vitreous interface, then use the vitrectome's suction to cautiously induce a PVD(Fig. 8.8).
(5) Posterior VitreousResection
Once the PVD is induced, the posterior hyaloid interface becomes easier to identify.
While extending the PVD, carefully monitor for tight vitreoretinal or vitreovascular
adhesions. Avoid aggressive aspiration in these areas to minimize the risk of bleeding or iatrogenic retinal breaks.
(6) Peripheral Shaving and Scleral Indentation
After the posterior pole is cleared, perform scleral indentation to check the peripheral retina for pre-existing or iatrogenic tears (Fig.8.9). Residual vitreous in the
periphery is a primary risk factor for postoperative tractional detachment; however,
the shaving process itself must be meticulous to prevent new tears. In the event of a
retinal break, shave offthe surrounding vitreous, control any bleeding, and apply
endolaser treatment to seal the site.
ab
Fig. 8.8 Evaluating PVD using the “blowing and aspirationtests.” (a) Blowing the hemorrhagic
area with a ute needle reveals that blood can becompletely cleared from the retinal surface, indicating complete vitreous resection. Blood is easily cleared from the retinal surface with a ute
needle,indicating a complete PVD and adequatevitreousremoval. (b) Blood accumulates in stubborn patches that resist aspiration, conrming that it is “trapped” beneath the posterior hyaloid.
This nding indicates that an intact posterior vitreous cortex is still adherent to the retinal surface
8.4 Surgical Treatment ofVitreous Hemorrhage
Fig. 8.9 Scleral
indentation and peripheral
repair. Identication of a
peripheral retinal tear via
scleral indentation,
followed by thorough
vitreous base shaving and
laser retinopexy to seal the
lesion
175
(7) Comprehensive Pan-retinal Photocoagulation (PRP)
Once PDR is conrmed as the etiology of the vitreous hemorrhage, extensive PRP
is indicated. The integration of wide-angle viewing systems has signicantly
streamlined intraoperative laser delivery. It is generally recommendedtoextendfrom
the vascular arcades to the post-equatorial region, reaching just posterior to the ora
serrata.Laser parameters must be adjusted dynamically. Given that laser scars typically expand by approximately 50% during the postoperative healing phase, adequate spacing between spots must be maintained (Fig.8.10). While a symmetrical
arrangement of laser spots is aesthetically ideal, clinical efcacy depends primarily
on the total coverage area rather than the alignment pattern. Excessive energy levels
should be avoided to minimize the risk of iatrogenic, laser-induced retinal breaks.
Furthermore, focal photocoagulation can be applied to target localized vascular
leakage. For patients with prior incomplete laser treatment, supplementary peripheral PRP should be performed under scleral indentation to ensure comprehensive
coverage in a single surgical session (“single-stage completion”).
Novice surgeons must strictly avoid iatrogenic macular injury. When initiating
laser therapy, the following safety protocol is essential: (1) verify the operative eye
once more; (2) identify the macular boundaries, noting that macular edema may
obscure the foveal reex and prolonged intraoperative manipulation can diminish
fundus visibility; and (3) rst delineate the macula by placing an initial row of protective laser spots around its periphery.
(8) Choosing the Optimal Tamponade
If retinal proliferation is mild, balanced salt solution (BSS) can be used. For some
patients, ltered air or inert gas may be selected based on specic conditions; silicone oil tamponade is generally unnecessary.
176
Fig. 8.10 Pan-retinal
photocoagulation. Minor
bleeding sites are
manageable after most
areas have been treated
with laser; completing the
PRP rst helps stabilize the
overall fundus environment
8 Surgical Management ofDiabetic Retinopathy
(9) Postoperative Anti-Inflammatory Therapy
PDR and extensive intraoperative laser treatment often predispose patients to severe
postoperative inammation. In such cases, enhanced local anti-inammatory regimens are necessary. Additionally, mydriatic eye drops should be prescribed to maintain pupillary activity and reduce the risk of inammatory complications like pupil
seclusion.
8.4.4 Management ofPostoperative Recurrent Hemorrhage
Recurrent VHoccurs in approximately 30% of patients postoperatively. While it
causes patient anxiety, thorough preoperative counseling can mitigate this pressure.
Most cases resolve spontaneously within 2–3 weeks, especially in an “aqueous
eye” (post-vitrectomy without tamponade) where blood dilutes rapidly. Starting one
week post-surgery, B-scan ultrasonography should be used to monitor blood volume and retinal status. If the retina is visible and the initial PRP is adequate, observation is typically sufcient. However, surgeons must monitor for elevated IOP,
corneal staining, and iris neovascularization.
About 10% of patients require a repeat vitrectomy. While generally less complex, the surgery carries risks of sudden hypotony, globe collapse, and choroidal
hemorrhage during port creation. Using valved trocars enhances safety.
Intraoperatively, the focus should be on identifying bleeding sites and applying
supplementary laser therapy; electrocoagulation is not generally recommended as
the rst option to managethe bleeding sites.
8.5 Techniques forRelieving Vitreoretinal Traction
177
8.5 Techniques forRelieving Vitreoretinal Traction
Tractional retinal detachmentin PDR is frequently accompanied by varying degrees
of VH.However, due to vitreous contraction and dense adhesions, the VH is often
localized rather than diffuse. For novice surgeons, the primary challenge lies in the
meticulous relief of vitreoretinal traction.
If scleral buckling is likened to “the delicate crafting of a work of art,” PDR surgery is akin to “the strategic encirclement and neutralization of a formidable army.”
It demands not only technical prociency but also strategic planning, perseverance,
and clinical courage.
To master these complexities, beginners must move beyond basic skills and integrate their technical expertise with a deep understanding of intraocular instrument
mechanics. This synergy is essential to fully leverage the advantages of modern
micro-incisional vitrectomy.
The procedure typically begins with the identication of the posterior hyaloid
interface. When a PVD is present in the mid-periphery, a clear gap often exists
between the hyaloid and the underlying retina. The surgeon should rst utilize the
vitrectome to incise this mid-peripheral interface, thereby creating a "safe surgical
channel" for instruments to access the posterior pole (Fig.8.11).
The next phase involves the relief of brovascular membrane traction. Regardless
of whether a single-handed or bimanual approach is used, the surgeon typically
employs three fundamental, interrelated techniques for membrane dissection. These
maneuvers must be strategically integrated based on the specic morphology and
severity of the lesion to achieve optimal clinical outcomes.
Fig. 8.11 Incision of the
mid-peripheral posterior
hyaloid
178
8 Surgical Management ofDiabetic Retinopathy
8.5.1 Segmentation Technique
As the most common approach, segmentation follows a “divide and conquer” strategy. Using a small-gauge vitrectome in high-cut-rate, low-vacuum mode, surgeons
can partition expansive brovascular membranes into smaller segments across
the fundus.
This technique is ideal for resecting bridging membranes with an underlying
sub-membranous space (Fig. 8.12). While accessible for beginners, the primary
challenge is the precise depth perception required to avoid iatrogenic retinal injury,
tears, or hemorrhage while “conquering” each segment.
Following segmentation, the remaining membrane fragments can be meticulously debulked using the vitrectome.
8.5.2 Delamination Technique
For membranes with diffuse, moss-like adhesions and no clear surgical plane for
segmentation, delamination is required to cautiously peel the membrane from the
underlying retina (Fig.8.13).
In a single-handed approach, intraocular forceps are typically used to expand the
delamination from the area of least resistance. When membranes are present at the
optic disc, peeling can be initiated peripapillarly (Fig. 8.14 ), using the endoilluminator tip for gentle blunt separation of rmer adhesions. If adhesions are
ab
Fig. 8.12 Segmentation of bridging proliferative membranes. (a) The brovascular membrane
spans between two vessels, with dense adhesions at the vascular walls (green arrows). These focal
membranous space exists between the membrane and the underlying retina (blue dashed area),
forming a “bridge” conguration. (b) Using a 25G vitrectome, the bridging membrane is incised
at its point of maximum elevation to safely expose the underlying retina
points act as “bridge piers” and are prone to tearing; thus, forceful peeling must be avoided. A sub-
8.5 Techniques forRelieving Vitreoretinal Traction
179
ab
Fig. 8.13 Delamination technique. (a) The brovascular membrane is gently elevated using a
vitrectome toevaluate the extent and tenacity of vitreoretinal adhesions,ensuring a controlled dissection. (b) Using intraocular forceps, delamination is initiated from the area of least resistance
(the “loose edge”). Focal, striated adhesions between the membrane and retinal vasculature
become visible (green arrows)
Fig. 8.14 Peeling the
proliferative membrane
near the optic disc with
intraocular forceps
180
extremely tenacious, forced peeling must be avoided; the surgeon should instead
seek alternative surgical planes. If a plane cannot be established, dissection should
not be forced to prevent iatrogenic injury.
The bimanual technique is particularly effective for complex delamination.
Utilizing a chandelier illumination system, the surgeon uses one hand to tension the
membrane edge with intraocular forceps, while the other hand employs a vitrectome
or intraocular scissors to release vitreoretinal adhesions. The primary advantage is
the enhanced exibility in identifying surgical planes; intraocular scissors can facilitate sharp dissection to create or expand these planes where blunt separation fails.
However, this approach has a steep learning curve; improper execution can compromise efciency and increase the risk of iatrogenic retinal injury.
8 Surgical Management ofDiabetic Retinopathy
8.5.3 En Bloc Technique
The “En bloc” technique (derived from the French for “as a whole”) is a strategic
approach akin to a “surgical strike.” Its primary objective is to release adhesions
between the posterior pole membrane and the retina with minimal manipulation.
This method uniquely leverages the anteroposterior traction—the very force that
causes TRD—as a functional “third hand.” This inherent tension tautens the membrane, mimicking the effect of intraocular forceps in bimanual surgery and facilitating precise dissection.
In clinical practice, all three techniques—segmentation, delamination, and en
bloc—share a common core principle: identify all vitreoretinal adhesion sites and
establish surgical planes to address the primary pathology. The goal is to “utilize the
membrane’s own force against itself” as an operational platform.When resecting
membranes, surgeons must minimize both the extent and intensity of traction
applied to the underlying retina. Novice surgeons should adhere to these tenets:
proceed with deliberate caution, allow sufcient time for diagnostic judgment, minimize redundant maneuvers, and maintain complications within a manageable
threshold.
8.6 Vital Dyes andIntraocular Tamponade Agents
8.6.1 Staining Agents
(1) Staining Agents
Surgeons utilize various chromodissection agents to enhance the visualization of
the vitreous and proliferative membranes. TAis commonly used, particularly when
managing non-liqueed vitreous with rm retinal adhesions or when PVD status is
ambiguous. TA effectively delineates the residual vitreous interface, enabling
8.6 Vital Dyes andIntraocular Tamponade Agents
181
ab
Fig. 8.15 ICG staining aids in identifying proliferative membranes. (a) After ICG injection, the
membrane edge becomes visible; trim it using a vitrectome, (b) Most of the proliferative membrane has been removed
precise resection. Other available agents for staining pathological tissues include
trypan blue, brilliant blue G (BBG), and indocyanine green (ICG).
(2) Common Application Methods
ICG is commonly used in China for its strong afnity for the ILM.Although it
stains vitreous and proliferative tissues weakly, the resulting color contrast highlights the underlying retinal surface, helping surgeons identify the precise margins
and course of brovascular membranes (Fig.8.15).
The use of these staining agents remains controversial due to potential retinal
toxicity, which may manifest as localized visual eld defects. However, it is generally accepted that such adverse effects are preventable by strictly controlling the
dosage and exposure duration. Several clinical strategies are available to mitigate risk:
1. Immediate dilution: When using standard concentrations (e.g., 5 mg/mL ICG),
the agent should be aspirated and diluted with the vitrectome immediately after
injection. This ensures sufcient rapid staining while preventing the prolonged
retention of high-concentration dye within the vitreous cavity.
2. Pre-injection dilution: The agent can be diluted with balanced salt solution
(BSS)—for instance, a tenfold dilution of 5 mg/mL ICG to 0.5 mg/mL. If